BigBrother Biochemistry Questions Book

Protein Structure 1 & 2

1- In an amino acid, the carboxyl group and amino group are separated from each other by a single ____________ atom.

a. nitrogen b. Sulphur c. hydrogen d. carbon

ANS: d

2- Amino acids used in the synthesis of proteins on a ribosome are

a. D-amino acids b. Mutated amino acids c. L-amino acids d. Fluorescing amino acids

ANS: c

3- Which bonds are present in two neighboring amino acids?

a. Glycosidic bonds b. Polypeptide bonds c. Amide bonds d. Hydrogen bonds

ANS: b

4- Which residues are present in histone proteins?

a. Lysine & proline

b. Glutamic acid & aspartic acid c. Arginine & Histidine d. Serine & Cysteine

ANS: c

5- Keratin is: a. Fibrous protein.

a. Globular protein b. Tripeptide. c. Histone. d. Conjugated protein.

ANS: a 6- An essential amino acid in man is:

a. Proline. b. Tyrosine. c. Methionine. d. Serine. e. Glycine

ANS: c

7- Formed of 3 alpha-polypeptide chains; and contains about 33% glycine:

a. Keratin b. Collagen c. Albumin d. Elastin

ANS: b

8- Thyroxin hormone is derived from:

a. Tyramine. b. Tyrosine. c. Tryptophan. d. Taurine. e. Tryptamin

ANS: b

9- Primary structure of proteins is determined by:

a. Peptide bonds b. Hydrogen bonds c. Disulfide bonds d. Electrostatic bond

e. Hydrophobic bonds

ANS: a

10- Secondary structure of proteins is determined by: a. Peptide bonds b. Hydrogen bonds c. Disulfide bonds d. Electrostatic bond e. Hydrophobic bonds

ANS: b 11- The protein bond that is NOT lost by denaturation is: a. Peptide bonds b. Hydrogen bonds c. Disulfide bonds d. Electrostatic bond e. Hydrophobic bonds

ANS: a

12- Tertiary structure of proteins is determined by: a. Hydrogen bonds b. Disulfide bonds c. Electrostatic bonds d. Hydrophobic bonds e. All of the above

ANS: e

13- The only amino acid that is ketogenic but NOT glycogenic

a. Isoleucine b. Tyrosine c. Leucine d. Phenyl alanine e. Lysine

ANS: c

14- Methionine and threonine are:

a. Phenol containing amino acids.

b. Basic amino acids

c. Acidic amino acids d. Non-essential amino acids.

e. Essential amino acids

ANS: e

15- All of the following about protein denaturation is true EXCEPT:

a. It is loss of primary, secondary, tertiary and quaternary structures.

b. It causes loss of biological activity of proteins. c. Denaturated proteins are easily precipitated. d. Strong acids can cause protein Denaturation

ANS: a 16- Cysteine, cystine and methionine are:

a. Essential amino acids b. Non-protein amino acids c. Acidic amino acids d. Sulfur containing amino acids

ANS: d

17- Elastin is:

a. Scleroprotein b. Chromoprotein c. Metaloprotein d. Phosphoprotein e. Glycoprotein

ANS: a

18- Collagen is:

a. Insoluble in most protein solvents

b. By boiling it gives gelatin

c. Rich in glycine

d. Very firm structure e. All of the above

ANS: e

19- Aspartic acid and glutamic acid are:

a. Essential amino acids b. B. Acidic amino acids c. Rich in basic proteins d. Rich in collagen

ANS: b

20- Ceruloplasmin is: a. Chromoprotein b. Metalloprotein c. Phosphoprotein d. Glycoprotein

ANS: b

21- A heterocyclic amino acid is: a. Tryptophan b. Phenyl alanine c. Tyrosine d. Lysine e. Isoleucine

ANS: a

22- The amphoteric property of amino acids is due to the presence of: a. Amino group b. Carboxyl group c. Amino and carboxyl groups d. Indole group e. Phenyl group

ANS: c

23- Leucine is:

a. Basic amino acid b. Pure Ketogenic amino acid c. Non-essential amino acid d. Heterocyclic amino acid

ANS: b

24- Which one of the following statements about the major collagen type from skin or bone is INCORRECT:

a. One third of the amino acids of collagen is glycine. b. Ascorbic acid is required for the synthesis of collagen. c. The collagen molecule contains nonhelical chains. d. Collagen molecule is trimmer composed of three monomers, each containing approximately 1050 amino acids. e. By boiling, collagen molecule gives gelatin.

ANS: c 25- Albumin, globulin, histones and scleroproteins belong to the class of:

a. Simple proteins b. Conjugated proteins c. Derived proteins d. Basic proteins e. Acidic proteins

ANS: a 26- All of the following are sulfur containing amino acids EXCEPT: a. Cysteine b. Homocysteine c. Cystine d. Methionine e. Threonine

ANS: e 27- Methionine is:

a. Acidic amino acid b. Basic amino acid c. Sulfur containing amino acid d. Hydroxyl containing amino acid e. Aromatic amino acid

ANS: c 28- Lysine is:

a. Neutral amino acid b. Acidic amino acid c. Basic amino acid

d. Heterocyclic amino acid e. Aromatic amino acid

ANS: c 29- Collagen is rich in: a. Glycine, proline and hydroxyproline b. Glutamate proline and hydroxyproline c. Glycine, cycteine and cyctine d. Valine, leucine and isoleucine

ANS: a 30- A vasodilator substance is produce by a decarboxylation of: a. Methionine b. Histidine c. Glutamate d. Threonine e. Phenylalanine

ANS: b 31- All of the following are hydroxy (OH) containing amino acids

EXCEPT: a. Serine b. homoserine c. Threonine d. Glycine

ANS: d 32- A phosphoprotein is: a. Casein b. Albumin c. Globulin d. Histones

ANS: a 33- A basic protein associated with nucleic acids is: a. Actin b. Myosin

c. Histone

d. Collagen

ANS: c

34- Amino acids considered non essential for human are:

a. Those incorporated into protein. b. Those synthesized in the body. c. Those cannot decarboxylated d. Those cannot be transaminated.

ANS: b

35- Sulfur containing amino acid is:

a. Keratan sulfate. b. Chondroitin sulfate. c. Cysteine. d. Homoserine. e. Glutathione.

ANS: c 36- Glutathione is tripeptide formed of:

a. Glutamate- phenylalanine- aspartate b. Methionine - alanine - valine. c. Homocysteine - arginine threonine. d. Cystine - leucine Aspartate. e. Glutamate - cysteine - Glycine.

ANS: e

37- The terms "primary", "secondary" and "tertiary" structure in protein chemistry refer to:

a. "a-Helix", "b-helix" and "y-helix" respectively. b. "Amino acids sequence”, "hydrophobic, electrostatic, disulfide, hydrogen bonds" and "a-helix" respectively.

c. "Electrostatic interactions”, “hydrogen bonds" and “disulfide bonds" respectively. d. "Amino acids sequence", "a-helix", and "hydrophobic, electrostatic, disulfide, hydrogen bonds" respectively.

ANS: d

38- The following are basic essential amino acids EXCEPT:

a. Histidine

b. Lysine

c. Arginine d. Leucine

ANS: d 39- The bonds present in the primary structure of proteins

a. Hydrogen bonds b. Peptide bonds c. Disulfide bonds d. Electrostatic bonds e. All of the above

ANS: b

40- A newborn has milky white skin, white hair, and red appearing eye color. This disorder most often results from a defect in which of the following enzymes? Select one:

a. Tyrosinase

b. Phenylalanine hydroxylase

c. Dihydrofolate reductase d. NADPH oxidase e. Homogentisic acid oxidase

ANS: a

41- The pigment melanin: Select one:

a. Always contains Sulphur derived from cysteine b. Is formed from tryptophan

c. Is present in skin in order to absorb UV radiation to protect underlying structures d. Is formed in albinos

ANS: c

42- Histamine, a chemical mediator of allergies and anaphylaxis, is synthesized from which amino acid Select one:

a. Ornithine b. Arginine c. Glutamic acid d. Histidine ANS: d

Enzymes

Previous Exams & formatives:

1- What is the nature of enzyme:

a. Fibrous protein b. Globular protein c. Mixed nature d. None of the above

Answer: b

2- Factors affecting velocity of enzyme reaction include the following except:

a. Temperature b. Hydrogen ion concentration PH c. Substrate concentration d. Enzyme specificity

Answer: d

3- Types of enzyme reversible inhibition include all of the following except: a. Competitive b. Uncompetitive c. Non-competitive d. Irreversible

Answer: d

4- Holoenzymes is composed of:

a. Apoenzyme + cofactor b. Apoenzyme + catalyst c. Zymogen + catalyst d. None of the above

Answer: a

5- Enzyme in inactive form called:

a. Zymogen b. Holoenzyme c. Apoenzyme d. Catalyst

Answer: a 6- Some terms are used for the description of non-protein part of an enzyme. Point out the term of non-protein part, which easily dissociates from polypeptide chain:

a. Apoenzyme b. Coenzyme c. Prosthetic group d. Cofactor e. Metal ions Answer: d 7- The effect of competitive inhibitors on Vmax is: a. Increase Vmax b. No change c. Decrease Vmax d. None of the above Answer: c

8- Enzymatic system is called:

a. Apoenzyme b. Co-enzyme c. Catalyst d. Holoenzyme e. Proenzyme Answer: d

9- The effect of uncompetitive inhibitors on Km is:

a. Increase Km b. Decrease Km c. No change d. Both a & b e. Increase Vmax

Answer: b

Extra:

1- What is an apoenzyme?

a. It is a protein portion of an enzyme b. It is a non-protein group c. It is a complete, biologically active conjugated enzyme d. It is a prosthetic group

Answer: a

2- The General Mechanism is that an Enzyme Acts By: a. Reducing the activation energy b. Increasing activation energy c. Decreasing pH value d. Increasing the pH value

Answer: a 3- Which One Among them is the Example of Competitive Inhibition of an Enzyme: a. Cytochrome oxidase by cyanide b. Hexokinase by glucose-6-phosphate c. Carbonic anhydrase by carbon dioxide d. Antineoplastic drug methotrexate

Answer: d 4- Enzymes are Polymers of:

a. Hexose sugar b. Amino acids c. Fatty acids d. Inorganic phosphate

Answer: b

5- The Enzyme Which Hydrolyses Starch to Maltose is: a. Maltase b. Protease c. Lactase d. Amylase Answer: d 6- Optimum pH Value of Pepsin is: a. 7.4 b. 3.5 c. 1.6 d. 8 Answer: c

7- Non-Protein Component of Enzymes are Known as: a. Cofactor b. Activator c. Coenzyme d. All of these Answer: d

8- Which Among them is not Attribute of Enzymes: a. Specific in nature b. Protein in chemistry c. Consumed in reaction d. Increased rate of reaction Answer: c

9- Ribozymes are:

a. RNA acting as enzymes

b. Ribose sugar acting as enzyme

c. Antibodies acting as enzymes

d. Protein acting as enzyme

Answer: a

10- Enzymes are generally named after the ________

a. compound on which they work

b. compound which they form as product c. medium in which they act d. place from where they are derived

Answer: a 11- Lock and Key model is also known as

a. Template model

b. Induced fit model c. Kos land’s model d. Enzyme-substrate interaction model

Answer: a

12- Which of the following is INCORRECT for the lock-and-key model?

a. It is used to describe the binding process

b. The active site of the enzyme is complementary to the substrate c. It demonstrates enzyme-substrate complex d. The binding of the substrate produces a conformational change in enzyme.

Answer: d

13- Rate of the reaction is ............ proportional to the enzyme concentration when sufficient substrate is present.

a. Inversely b. Directly c. No relation

Answer: b

14- Accumulation of product in a reaction cause .............of enzyme activity:

a. Activation

b. Inhibition

c. Activation followed by inhibition d. No effect

Answer: b

15- The number of models that represent enzyme-substrate model are:

a. one b. Four c. two d. five

Answer: c

Isoenzymes

Previous Exams & Formatives:

1- Creatine kinase is highly found in:

a. Heart muscle b. Kidney c. Spleen d. Lung

Answer: a

2- Normal value of LDH in serum is:

a. 7-30 U/L b. 100-200 U/L c. 40-100 U/L d. 150-300 U/L Answer: b 3- The specific method of separation of isoenzymes is: a. Heat inactivation b. Chemical inhibition c. Electrophoresis d. Chromatography Answer: c

4- M subunit of creatinine kinase (CK) is present in:

a. Skeletal muscles b. Brain c. Fat cells d. Osteocytes

Answer: a

5- The highest level of LDH is present in:

a. Brain

b. Heart c. Kidney d. Muscles

Answer: b

6- The difference between isoenzymes is in:

a. Method of separation

b. Catalytic site and tissue distribution c. Botha a & b d. None of the above e. Motility

Answer: c

7- LDH1 is the....in migration on gel electrophoresis.

a. Slowest b. Fastest c. Modrest d. None of the above

Answer: b Extra:

1- What is an Isozyme?

a. Same structure, different function

b. Different structure, the same function

c. Same structure, the same function d. Different structure, different function

Answer: b

2- creatine kinase is highly found in:

a. Skeletal muscle

b. Kidney

c. Spleen

d. Lung

Answer: a 3- Isoenzymes are:

a. Chemically, immunologically and electrophoretically different forms of an enzyme.

b. Different forms of an enzyme similar in all properties

c. Catalyzing different reactions

d. Having the same quaternary structures as the enzymes

Answer: a

4- The isoenzymes of LDH:

a. Differ only in a single amino acid

b. Differ in catalytic activity

c. Exist in 5 forms depending on M and H monomer contents d. Occur as monomers

Answer: c

5- The isoenzymes LDH5 is elevated in:

a. Myocardial infarction

b. Peptic ulcer

c. Liver disease d. Infectious diseases

Answer: c

6- On acute myocardial infarction the enzyme elevated is:

a. Serum LDH3

b. Serum LDH2

c. Serum LDH1 d. Serum LDH4

Answer: c

7- Isoenzymes can be separated by:

a. Heat b. inactivation

c. Chemical inhibition d. Electrophoretic techniques

e. All of the above

Answer: d

8- Which of the following is not true for creatine kinase?

a. Its activity is greatest in striated muscle, brain and heart tissue b. It catalyzes L-lactate to pyruvate

c. It is a dimer d. It has three isoenzymes

Answer: b

9- CK1: brain, CK3: _________________

a. Kidney b. Spleen

c. Skeletal muscle d. Cardiac tissue

Answer: c

10- Which is the only tissue which has mixed MB (CK2) isoenzyme?

a. Prostate b. Liver

c. Cardiac tissue d. Spleen Answer: c

VITAMINS

4- According to Vitamin A:

d. Vitamin B2

Answer: b

9-Mark the INCORRECT statement about Ascorbic acid.

a. It is a strong reducing agent

b. It can have synthesized in the body c. Involves in hydroxylation of prolyl- and lysyl- residues of collagen d. Shows antioxidant activity

Answer: b

10- Name the vitamin which functions as hormone as well as visual pigment?

a. Thiamine

b. Riboflavin c. Retinol d. Folic acid Answer: c

11- Name the vitamin which takes part in blood clotting?

a. Vitamin E b. Vitamin D c. Vitamin K d. Folic acid

Answer: c

12- Which of the following vitamin is involved in coenzyme function in transamination?

a. Nicotinamide

b. Pyridoxine c. Thiamine

d. Riboflavin

Answer: b

13- Which of the following is a component of the coenzyme A?

a. Retinol b. Pantothenic acid c. Pyridoxine d. Retinoic acid

Answer: b

14 -The vitamin required for the formation of hydroxyproline (in collagen) is Select one :

a. Vitamin D b. Vitamin E c. Vitamin C d. Vitamin A Answer: c

15- Which of the following vitamins can't be stored in the body?

a. vitamin C b. vitamin A c. vitamin B d. both a & c

Answer: d

16- Which of the following is water soluble?

a. menaquinone b. phylloquinone c. Menadione d. all of the above

Answer: c

17- Which one of the following is the most potent?

a. Menadione b. menaquinone c. phylloquinone

Minerals

Previous exams & formatives:

1- Iron deficiency causes:

a. Megaloblastic anemia b. Microcytic anemia c. Normocytic anemia d. None of the above

2- All are true for Bronzed diabetes except:

a. It causes hepatic cirrhosis b. Due to excess intake of copper c. Responsible for skin discoloration d. None of the above

3- Which one of the following minerals is deposited in tissues in Wilson’s disease? a. Iron b. Potassium c. Copper d. Calcium

4- Zinc is required by…. for its storage and secretion. a. Insulin b. Adrenaline c. Cortisol d. Glucagon

Extra:

6- Which of the following are examples of macro minerals?

a. Sodium b. Calcium c. Chloride

d. All of the above

7- Excessive intake of calcium in our diet results in ___________.

a. Stroke b. Diarrhoea c. Constipation d. Kidney stones

8- Which of the following are examples of micro minerals?

a. Cobalt b. Copper c. Iron d. All of the above

Answers: 6-d 7-d 8-d

Chemistry of Carbohydrates

Previous Exams & formatives

1- The following are pentose except:

a. Ribose b. Xylose c. Erythrose Answer: c

2- All are aldohexoses except: a. Fructose b. Glucose c. Galactose Answer: a

3- The following are monosaccharide except: a. Glucose b. Arabinose c. Lactose Answer: c

4- Which of the following is a ketose sugar?

a. Ribose b. Ribulose c. Glucose d. Mannose

Answer: c

5- Polysaccharides are: a. Polymers b. Acids c. Proteins d. Oils e. Unit Answer: a 6- Choose from these carbohydrates the disaccharide: a. Glycogen b. Cellulose c. Starch d. Glucose e. Sucrose Answer: e 7- Which of the following molecules is smallest? a. Sucrose b. Glucose c. Glycogen d. Starch e. Mucus Answer: b 8- Which term describes the largest group of biochemicals? a. Glucose

b. Amylose c. Sucrose d. Carbohydrates e. Fructose Answer: d 9- All of the following are storage carbohydrates except: a. Starch b. Glycogen c. Amylopectin d. Amylose e. Cellulose Answer: e 10- Which is not a function of carbohydrates ( in general )? a. Structural support b. Immediate energy c. Energy storage d. Enzymatic catalysis e. All are carbohydrates functions Answer: e 11- The exoskeleton of many insects is made chitin which is a modified form of: a. Carbohydrates b. Lipid c. Protein d. Nucleic acids e. Phospholipid Answer: a

12- All of the following are digestible carbohydrates except: a. Starch b. Glycogen c. Cellulose d. Glucose Answer: c

13- Hexokinase present in all tissues except: a. Intestine b. Kidney c. Liver d. Adipose tissue Answer: c

14- Which of the following type of metabolite is used for generating glucose under severe starvation conditions?

a. Amino acids b. Fats c. Glycogen d. Starch Answer: a

15- Which carbohydrate will you find in greatest abundance in potates?

a. Starch b. Cellulose c. Sucrose d. Glycogen Answer: a

A polysaccharide indigestible by man is: a. Cellobiose b. Glycogen c. Amylopectin d. Cellulose Answer: d

17- The only sulfur free heteropolysaccharides is: a. Chitin b. Hyaluronic c. Heparin d. Inulin

Answer: b

18- The polysaccharide found in the exoskeleton of invertebrates is: a. Pectin b. Chitin c. Cellulose d. Chondritinsulphate Answer: b

Extra

1- The mother sugar of aldoses is: a. Dihydroxyacetone b. Acetaldehyde c. Erythrose Glyceraldehyde Answer: c

2- Dihydroxyacetone is characterized by: a. Presence of one asymmetric carbon atom b. Presence of 2 isomers c. Having no isomers Optically active Answer: c

3- Ribulose is a: a. Ketotetrose b. Aldotetrose c. Ketopentose d. Aldopentose Answer: c

A carbohydrate found only in milk: a. Galactose b. Glucose c. Maltose d. Lactose Answer: d

5- The simplest aldose carbohydrate is: a. Dihydroxyacetone b. Glyceraldehyde

c. Glucose d. Fructose Answer: b

6- The sugar in DNA is: a. Ribose b. Xylose c. Deoxyribose d. Ribulose Answer: c

7- Alpha glycoside bond is present in: a. Lactose b. Maltose c. Sucrose d. All Answer: b 8- (_OH) group is present on the right side of carbon atom: a. L_ Glyceraldehyde b. D_ Glyceraldehyde c. Glucose d. Fructose Answer: b

9- The polysaccharide which is used as anticoagulant is: a. Heparin b. Glycogen c. Cellulose Heparan sulfate Answer: a

10- The following is not a monosaccharide derivative: a. Sorbitol b. Glucuronic c. Dihydroxyacetone d. Glycerol Answer: c

Glycolysis

Previous Exams & Formatives:

1- Glucose is phosphorylated to glucose-6-phosphate by:

a. Hexokinase only b. Glucokinase only c. Either hexokinase or glucokinase d. Peptidase

Answer: c

2- Phosphoglucomutase converts:

a. Glucose-6-phosphate to Glucose-1-phoshate b. Glucose-6-phosphate to glucose c. Glucose-6-phosphate to fructose d. Glucose-6-phosphate to collagen

Answer: a 3- Glycolysis occur in: a. Mitochondria b. Golgi c. Cytosole d. Nucleous

Answer: c

4- The main source of energy in RBCs is:

a. Krebs b. Pentose shunt

c. Glycogenolysis

d. Glycolysis

Answer: d

5- Glucose-6-phosphate inhibits:

a. Hexokinase b. Glucokinase c. Both a, b d. None of the above

Answer: c

6- Irreversible enzyme in glycolysis is:

a. Phosphofructokinase1 b. Aldolase c. Enolase d. Aconitase Answer: a

7- Enzyme in glycolysis regulated by phosphorylation and dephosphorylation:

a. Phosphofructokinase b. Pyruvate kinase c. Hexokinase d. Enolase

Answer: b

8- Citrate inhibits: a. Hexokinase

b. Glucokinase c. Pyruvate kinase d. Phosphofructokinase

Answer: d

9- Fructose 2-6 bisphosphate stimulates:

a. Phosphofructokinase1 b. Pyruvate kinase c. Hexokinase d. Enolase

Answer: a

10- Cleavage of fructose1,6-bisphosphate yields:

a. Two aldoses b. Two ketoses c. An aldose and a ketose d. Only a ketose

Answer: c

11- Where do glycolysis leads to lactate production?

a. Liver b. Heart c. Cornea d. Medulla

Answer: c

12- Floride inhibits: a. Enolase

16- Whenever the cell's ATP supply is depleted, which of the following enzyme's activity is increased?

a. Hexokinase

b. Pyruvate kinase c. Glucokinase d. Phosphofructokinase-1

Answer: d

17- Glycolysis in nerves gives:

a. 6 ATP b. 4 ATP c. 2 ATP d. 8 ATP Answer: a 18- Fructose 2,6-biphosphate is formed by the action of a. Phosphofructokinase-1 b. Phosphofructokinase-2 c. Fructose biphosphate isomerase d. Fructose-1,6-biphosphatase Answer: b Extra:

1- What is glycolysis?

a. utilization of glucose b. synthesis of glucose c. synthesis of glycogen d. breakdown of glycogen

Answer: a

2- High concentration of glucose 6-phosphate is inhibitory to?

a. Hexokinase b. Pyruvate kinase c. Aldolase d. Phosphofructokinase

Answer: a

3- The product formed in the first substrate level phosphorylation in glycolysis is?

a. Pyruvate b. 3-phosphoglycerate c. 1, 3-bisphosphoglycerate d. 2-phosphoglycerate Answer: b 4- Glycolysis converts? a. Glucose into pyruvate b. Glucose into phosphoenolpyruvate c. Fructose into pyruvate d. Fructose into phosphoenolpyruvate Answer: a

5- Which substrate is used in the last step of glycolysis?

a. Glyceraldehyde 3-phosphate b. Pyruvate c. Phosphoenolpyruvate

d. 1, 3-bisphosphoglycerate

a. Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate b. Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate

c. Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3- phosphate d. Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate

a. Hexokinase

b. Pyruvate kinase

c. Glucokinase d. Phosphofructokinase

Answer: d 10- Which of the following is the first enzyme of glycolysis?

a. pyruvate dehydrogenase b. phosphofructokinase c. hexokinase d. None of the above

Answer: c

11- Which hormone stimulates glycolysis?

a. insulin b. glucagon c. growth hormone d. all of the above

Answer: a

12- Hexokinase is ..........dependent enzyme?

a. zinc b. magnesium c. sodium d. iron

Answer: b 13- Where does glycolysis leads to lactate production?

a. liver

b. erythrocytes

c. cornea d. medulla

Answer: b

14- Which enzyme is inhibited by iodoacetate and arsenate?

a. hexokinase

b. glucokinase

c. glyceraldehyde-3-phosphate dehydrogenase d. both a and b

Answer: c

15- Which of the following enzyme catalyzes the reversible reaction of glycolysis?

a. glucokinase b. phosphofructokinase c. pyruvate kinase d. none of the above

Answer: d

16- Which hormone inhibits glycolysis?

a. insulin

b. glucagon

c. growth hormone d. all of the above

Answer: b

17- Compared with the resting state, vigorously contracting skeletal muscle shows?

a. Decreased levels of fructose 2,6-bisphosphate.

b. Increased reduction of pyruvate to lactate.

c. Increased oxygen availability

d. Decreased AMP/ATP ratio

Answer: b

18- Uncoupling of oxidative phosphorylation implies that:

a. ATP formation stops but respiration continue

b. ATP formation stops and respiration stops

c. The ATPase activity of mitochondreia is abolished d. Cellular activities stops

Answer: a

19- Glycolysis in nerves gives?

a. 6 ATP

b. 2 ATP c. 8 ATP d. 4 ATP

Answer: a 20- A 47-year-old obese man complains of having to get out of bed three times a night to urinate (polyuria), being constantly thirsty (polydipsia), and eating more often (polyphagia). The patient is diagnosed with insulin resistant diabetes mellitus (type 2). If the patient’s symptoms are due to a problem at the level of the glucose transporter, which one of the tissues indicated below will be

most affected?

a. Muscle

b. Brain

c. Liver d. Small intestine e. RBCs

Answer: a 21- A 58-year-old woman with breast cancer presents with confusion, headaches, and persistent nausea. To evaluate for metastases to the brain, the oncologist orders a positron emissiontomography (PET) scan, which covalently links a radioactive isotope to glucose and reveals highly active areas in the body (e.g., a tumor). Which of the following proteins enables the tracer to remain in the cell?

a. Hexokinase

b. PFK-1 c. GLUT-4 d. Insulin e. GLUT-1

Answer: a 22- Which one of the following statements is correct concerning the formation of muscle lactate during exercise?

a. Lactate formation occurs when the NADH/ NAD+ ratio is high b. Lactate formation is less likely to be found in the eye, testes, and RBCs than in other tissues

c. The heart preferentially converts lactate into glucose d. The intracellular pH is typically increased when lactate is produced e. The liver preferentially converts lactate into carbon dioxide and water

Answer: a

23- An 8-year-old girl presents with polydipsia, polyuria, and fatigue. A urinalysis is significant for glucose. To differentiate between type 1 diabetes mellitus and maturity-onset diabetes of the young (MODY), an assay is run to identify one of the six proteins responsible for MODY. Results reveal a missense mutation in exon 7 of the glucokinase gene establishing MODY2. Which of the following is a significant characteristic of glucokinase?

a. The Km is above the fasting concentration of glucose in the blood

b. It is expressed only in muscle

c. It is expressed in many tissues

d. Its activity is inhibited by glucose 6-phosphate

e. Its activity is stimulated in response to fructose 2,6-bisphosphate

Answer: a 24- The substrate for aldolase is:

a. Fructose 1,6 diphosphate.

b. Fructose -6-phosphate

c. 1,3 diphosphoglycerate.

d. Glucose -6-phosphate

Answer: a 25- Available energy for muscle contraction is obtained during anaerobic Glycolysis from which of the following?

a. The conversion of 1, 3 diphosphoglycerate to 3- phosphoglycerate

b. The reduction of pyruvate to lactate

c. The conversion of 3- phosphoglyceraldehyde to 1, 3 diphosphoglycerate

d. The formation of fructose 1,6 diphosphate from fructose -6- phosphate

Answer: a

26- Which of the following enzymes of the glycolytic pathway is particularly sensitive to inhibition by fluoride ions?

a. Phosphohexose Isomerase

b. Aldolase c. Hexokinase d. Enolase

Answer: b

27- All of the following are inhibitors of the enzyme phosphofructokinase except:

a. ATP b. Citrate c. Cyclic AMP d. Glucagon

Answer: c

28- All of the following about glycolysis is true except:

a. NAD is required as a coenzyme b. 2,3 DPG may be produced in RBCs

c. Occurs in the cytosol d. There is a net energy prodcution

e. CO2 is produced

Answer: e

29- An example of substrate level phosphorylation is the reaction catalyzed by:

a. Glucose-6-phosphate dehydrogenase

b. Glyceraldehyde-3-phosphate dehydrogenase

c. Pyruvate kinase

d. Pyruvate carboxylase

e. Pyruvate dehydrogenase complex

Answer: c

30- Which of the comparison between hexokinase and glucokinase is false? Select one:

a. The Km of hexokinase for glucose is much smaller than that of glucokinase

b. Only hexokinase is inhibited by glucose-6- phosphate

c. Synthesis of glucokinase and not hexokinase is induced by insulin

d. Only glucokinase is present in the brain

e. Hexokinase is present in most tissues

Answer: d

31- Arsenate cause decrease in ATP produced from glycolysis by:

a. Six ATP b. Zero ATP c. Two ATP d. Four ATP

Answer: c

32- Pyruvate kinase deficiency effect on RBCs:

a. Decreased 2,3 DPG level in RBCs

b. Life span of RBCs is increased

c. Increased 2,3 DPG level in RBCs

d. No Effect on RBCs

8

Krebs cycle

Previous Exams & Formative:

1- A term that is used to describe the process that is both catabolic and anabolic.

a. Amphibolic b. Amphoteric c. Metameric

2- The compound that links the process of Glycolysis and Citric Acid Cycle: a. Oxaloacetate b. Pyruvate c. Acetyl CoA

3- In what part of eukaryotic cells does Krebs cycle occur? a. Cytoplasm b. Mitochondrial matrix c. Lysosome

4- It the compound which reacts with Acetyl CoA that enter Krebs cycle step1, and it is also the product when L-Malate is oxidized in step8: a. Alpha-ketoglutarate b. Oxaloacetate c. Succinyl CoA

Answers: 1-a 2-b 3-b 4-b

a. Alpha-ketoglutarate

b. Glutamine

c. NADHP d. H+ e. Succinyl CoA

6- The oxidation of lactic acid to pyruvic acid requires the following vitamin derivative as hydrogen carrier:

a. Lithium pyrophosphate b. Coenzyme A c. NAD+ d. FMN e. Thiamin

7- Each of the following statements about TCA cycle intermediates is true except:

a. They can be used for the net production of glucose b. They are all ketogenic c. Citrate is required for the synthesis of FAs in cytoplasm d. Two of them provide carbon skeleton for the synthesis of two AAs by transamination e. It is need oxygen

8- Citrate inhibits: a. Hexokinase b. Glucokinase c. Pyruvate kinase d. Phosphofructokinase

Answers: 5-a 6-c 7-b 8-d

9- Which of the following about the oxidative decarboxylation of pyruvate is correct:

a. The oxidative decarboxylation of pyruvate formed in aerobic glycolysis occurs in the cytosol.

b. The oxidative decarboxylation of pyruvate is catalyzed by the enzyme pyruvate decarboxylase.

c. The oxidative decarboxylation of pyruvate is reversible since there is a large decrease of free energy in the reaction.

d. The oxidative decarboxylation of pyruvate forms Acetyl CoA which is fed in the citric acid cycle

10- Pyruvate dehydrogenase enzyme is inhibited by the following except:

a. Arsenate b. Beri-Beri c. Pyruvate d. Pellagra

11- The only enzyme in Krebs cycle that is bound to inner mitochondrial membrane surface is:

a. Malate dehydrogenase b. Succinate dehydrogenase c. Citrate synthase d. None of the above

12- Substrate level phosphorylation in TCA cycle is in step:

a. Isocitrate dehydrogenase b. Malate dehydrogenase c. Aconitase d. Succinate thiokinase

Answers: 9-d 10-c 11-b 12-d

13- Pyruvate dehydrogenase complex and alpha ketoglutarate dehydrogenase complex require the following for their oxidative decarboxylation:

a. COASH and lipoic acid

b. NAD+ and FAD

c. COASH and TPP d. COASH, TPP, NAD, FAD and lipoate

14- COA SH enzyme is:

a. Hydrogen carrier b. One carbon group carrier c. Acid carrier d. Reduction

Answers: 13-d 14-c

Extra: 1- Tricarboxylic acid cycle to be continuous requires the regeneration of:

a. α-oxo glutaric acid b. Malic acid c. oxaloacetic acid d. Pyruvic acid

2- During Krebs Cycle, the pyruvate is oxidized to which molecule?

a. Oxygen b. Carbon dioxide c. Nitrogen d. Hydrogen

Answers: 1-c 2-b

3- The end-product of glycolysis, pyruvate entered which process?

a. Krebs cycle b. Citric acid cycle c. Electron transport chain

d. Both a and b

4- Which of the following metabolic intermediate activates the TCA cycle?

a. High NADH/NAD ratio b. High ADP/ATP ratio c. High Oxaloacetate d. None of the above

5- The entry of pyruvate into the TCA cycle is inhibited by the presence of a high cellular concentration of:

a. Pyruvate b. NADH c. Coenzyme A d. AMP 6- Which of the following is not formed during the Krebs cycle?

a. Lactate b. Isocitrate c. Succinate d. Both (a) and (b)

Answers: 3-d 4-c 5-b 6-a 7- For each molecule of glucose, how many times does the TCA cycle proceed?

a. 1 b. 2 c. 3 d. 4 8- The enzymes that required for Krebs cycle are located free in:

a. The matrix

b. The inner mitochondrial membrane c. Golgi apparatus d. both a & b

9- ............is a common pathway for oxidation of all nutrients carbohydrate, lipids and proteins

a. Krebs' cycle b. Citric Acid cycle c. Tricarboxylic acid cycle d. All the above

10- Concentration of pyruvic acid and lactic acid in blood is increased due to deficiency of the vitamin?

a. Riboflavin b. Pantothenic acid c. Niacin d. Thiamin

Answers: 7-b 8-d 9-d 10-d

11- The Vitamin B1 deficiency causes———

a. Pellagra. b. Ricket c. Beriberi. d. Nyctalopia

12- Which molecule will combine with the four-carbon oxaloacetate in the TCA cycle to form the six-carbon citrate?

a. lactic acid b. NADH c. ATP d. acetyl-CoA

13- Which pathway will result in the production of four carbon dioxide molecules, two ATP molecules, NADH2 and FADH2?

a. glycolysis

b. Krebs cycle

c. Calvin cycle d. electron transport system

14- The TCA Cycle is an _____________ pathway.

a. catabolic b. anabolic c. amphibolic d. respiratory

Answers: 11-c 12-d 13-b 14-c

5- Which of the following complex of electron transport chain contains cupper ?

a. Cytochrome Q b. Cytochrome C c. Cytochrome A,A3 d. Cytochrome B

6- Which out of the following has the highest redox potential ?

a. NAD b. FMN c. FAD d. O2NADH dehydrogenase-Q reductase

7- Substrate level of phosphorylation:

a. Occurs at phosphoglycerate kinase and pyruvate kinase in glycolysis b. Does not occur in Kreb’s cycle c. Occurs at succinyl thiokinase in Kreb’s cycle d. Occurs only at phosphoglycerate kinase

8- NAD is considered an electron transporter in complex: a. 1 b. 5 c. Both of them d. None of the above 9- All complexes produce ATP except: a. Complex 1 b. Complex 2 c. Complex 3 d. Complex 4 5-c 6-d 7-a 8-a 9-b

Extra questions:

1- Which one out of the following is not a NAD+requiring enzyme?

a. Lactate dehydrogenase b. Pyruvate dehydrogenase complex c. Maltate dehydrogenase d. Acyl co-A dehydrogenase

2- Loss of electrons can be termed as _____

a. Metabolism b. Anabolism c. Oxidation d. Reduction

3-Which of the following is the prosthetic group of NADH dehydrogenase?

a. NADH b. FAD c. NADPH d. FMN 4- If 2, 4-dinitrophenol is added to tightly coupled mitochondria that are actively oxidizing succinate ______

a. Electron flow will continue but ATP synthesis will not occur b. Electron flow will continue but ATP synthesis will be increased c. Electron flow will cease but ATP synthesis will continue d. Both electron flow and ATP synthesis will be ceased

1-d 2-c 3-d 4-a

5- Which of the following takes place in substrate level phosphorylation?

a. Oxidation of one molecule of substrate is linked to synthesis of more than one ATP molecule b. High energy intermediate compounds cannot be isolated c. Only mitochondrial reactions participate in ATP formation d. Substrate reacts to form a product containing a high energy bond

9- Products of glucose oxidation essential for oxidative phosphorylation are

a. Pyruvate

b. Acetyl co-A

c. NADPH and ATP d. NADH and FADH2

10- In a eukaryotic cell, most of the enzymes of the electron transport chain are located in the…..

a. Cytosol b. outer mitochondrial membrane c. inter-membrane space d. inner mitochondrial membrane

11-

Coenzyme Q is involved in electron transport

a. as a lipid-soluble electron carrier b. as a water-soluble electron donor c. as a covalently attached cytochrome cofactor d. as a water-soluble electron acceptor

9-d 10-d 11-a

Free radicals & Antioxidant 10

Previous Exams & Formatives:

1- The beneficial effect of free radicals is called: a. Lipid peroxidation b. Respiratory burst c. DNA mutation d. None of the above e. Oxidative stress Answer: b

2- Nutrient Antioxidant is: a. Vitamin c b. Uric acid c. Glutathione peroxidase d. None of the above e. Glucose Answer: a

Extra:

1- Which of the following is not a free radical? a. Hydroxyl radical b. Ozone c. C-Nitric oxide d. D-Hydrogen peroxide Answer: b

2- Role of free radicals in the body is: & Antioxidants a. harmful only b. beneficial only c. both a and b d. none of the above Answer: c

3- Glutathione peroxidase is: a. chain breaking antioxidant b. preventive antioxidant c. reparative antioxidant d. none of the above Answer: b

4- All of the following are antioxidants except: a. vitamin c b. vitamin E c. C-selenium d. glycine Answer: d

5- Vitamin C is: a. nutrient antioxidant b. b-enzymatic antioxidant c. metabolic antioxidant d. d-none of the above Answer: a

6- Which of the following is the major source of NADPH? a. VA shunt b. HMP shunt c. C-VPL shunt d. LP shunt Answer: b

7- Enzyme which catalyze the reaction H2O2 give H2O + O2: a. catalase b. b-glutathione reductase c. glutathione peroxidase d. d-glutathione transferase Answer: a

8- Which of the following is Preventive antioxidant? a. Superoxide dismutase b. B-vitamin E

c. C-uric acid. d. D-catalase Answer: d

9- Which enzyme converts superoxide (O2) to hydrogen peroxide & O2: a. catalase b. glutathione peroxidase c. c- Superoxide dismutase d. d- none of the above Answer: c

10- All of the following is metabolic antioxidant except: a. glutathione b. Ceruloplasmin c. Glutathione reductase d. Albumin Answer: c

11- Propagation phase occur under; a. aerobic conditions b. B-anaerobic c. both a and b d. None of the above Answer: a

12- What are the sources of free radicals; a. Result of drug metabolism b. damage caused by ionizing radiations on tissues (X-rays) c. Photoexcitation of organic molecules d. d- all of the above Answer: d

13- Which of the following is not an oxygen derived free radical (ROS)?

a. Nitric oxide b. Hydrogen peroxide c. Superoxide anion

d. Hydroxyl radical Answer: a

14- Which of the following can’t form free radicals?

a. Xenobiotics b. Carbohydrates c. Oxygen d. Lipids Answer: b

15- Which of the following lipid is most affected by free radicals?

a. long chain fatty acids b. Polyunsaturated fatty acids c. Saturated fatty acids d. Monounsaturated fatty acids Answer: b

16- Iron is a transitional metal that increases the formation of free radicals?

a. True b. False Answer: a

17- Free radicals are completely hazardous to the human body and they have no beneficial effect: a. True b. False Answer: b

18- Albumin is considered a secondary antioxidant: a. True b. False Answer: a

Previous exams & Formative:

5- Von Gierke's disease is due to:

a. deficiency of glucose-6-phosphatase

b. deficiency of branching enzyme

c. deficiency of acid maltase

d. deficiency of debranching enzyme

6- In case of low blood glucose concentration, the negative feedback is:

a. Conversion of glucose into glycogen

b. Conversion of glucose into fat

c. Conversion of glycogen into glucose

d. Increase arterial blood pressure

7- Glycogenin is:

a. Uncoupler of oxidative phosphorylation

b. Polymer of glycogen molecule

c. Protein primer for glycogen synthesis

d. Intermediate in glycogen breakdown

1-b 2-a 3-d 4-b 5-a 6-c 7-c

8- A 28-year-old professional cyclist has been training for an opportunity to race in the Tour de France. His coach strongly suggests that he consume carbohydrates after each of his workouts to ensure that his muscle glycogen storage can endure the 28-day race. The activity of muscle glycogen synthase in resting muscles is increased by the action of which of the following?

a. Glucagon

b. Phosphorylation

c. Fasting and starvation d. Insulin e. Epinephrine 9- The allosteric activator of glycogen synthase D is: a. ADP b. Glucose-6-phosphate c. UTP d. Glucose-1-phosphate 10- Debranching enzyme is absent in a. Von Gierke’s disease b. Her’s disease c. Cori’s disease d. Andersen’s disease 11- Glycogen is converted to glucose-1- phosphate by a. Phosphorylase b. Branching enzyme c. Phosphatase d. UDPG transferase 8-d 9-b 10-c 11-a

Extra: 1- Glucagon and epinephrine has which of the following action on glycogen... a. Inhibit Glycogenolysis b. Stimulate Glycogenolysis

c. Inhibit Glycogenesis

d. Both b & c

2- Most amount of Glucagon is stored in

a. Skeletal Muscle b. Pancreas c. Kidneys d. Epithelial tissues

3- Which of the following enzyme’s gene expression is slowed by insulin?

a. Glycogen phosphorylase b. Glycogen phosphatase c. Glycogen hydrolase d. Glycogen phosphoglycosidase

4- Deficiency of the enzyme that releases glucose from glycogen, oligosaccharides and maltose results in

a. Limit Dextrinosis, Forbe's disease b. Pompe’s disease c. Andersen’s disease d. McArdle’s disease

5- The precursor to glycogen in the glycogen synthase reaction is

a. Glucose-1-P. b. Glucose-6-P. c. UDP-glucose. d. UTP-glucose.

c. Glycogen synthetase

d. Glycogen lyase

10- A patient complaining of painful cramps in the legs during exercise and has easy fatigability, the most likely cause is:

a. Diabetes mellitus b. Deficiency of glucose-5-phosphatase c. Deficiency of the debranching enzyme or muscle phosphorylase d. Defective glycogen synthesis e. Over-storage of glycogen 8-b 9-a 10-c

Gluconeogenesis

1- In human, gluconeogenesis: Select one:

a. Require the enzyme hexokinase

b. Help to reduce blood glucose after carbohydrate rich meal c. Is activated by the hormone insulin d. Can result in conversion of protein into blood glucose

Answer: d

2- What is achieved by the 'Cori cycle' which involves metabolism of lactate? Select one:

a. Metabolic alkalosis is prevented by removing lactate from the blood.

b. Lactate is used by the muscle for fuel.

c. Lactate is taken up by the liver for synthesis of glucose. d. Lactate is removed from the blood as it inhibits glycolysis in the erythrocyte.

Answer: c 3- Which of the following enzymes is deficient in adipose tissue? Select one:

a. Hexokinase

b. Hormone-sensitive lipase c. Glycerol-3- phosphate dehydrogenase d. Monoacyl glycerol lipase

e. Glycerol kinase

Answer: e 4- Which of the following is not an important precursor of glucose in animals?

a. Lactate b. Pyruvate

c. Glycerol

d. Glucose 6-phosphate

Answer: d

5- Which of the following statements is false about gluconeogenesis?

a. From the hydrolysis of tri-acyl-glycerol, fatty acids can be used as a carbon source

b. From red blood cells, lactate can be used as a carbon source

c. From the hydrolysis of tri-acyl-glycerol, glycerol is converted to glucose in gluconeogenesis

d. From muscle vigorous muscle activity, lactate can be used as a carbon source

Answer: a

6- Which enzyme catalyzes the conversion of pyruvate to oxaloacetate?

a. Pyruvate carboxylase

b. Pyruvate dehydrogenase

c. Pyruvate kinase

d. Phosphofructokinase-1

Answer: a

7- Oxaloacetate is reduced to malate by:

a. Pyruvate carboxylase

b. Malate dehydrogenase

c. Pyruvate kinase

d. Phosphofructokinase-1

Answer: b

8- Gluconeogenesis involves the conversion of:

a. Glucose to pyruvate

b. Pyruvate to glucose

c. Phosphoenolpyruvate to glucose

d. Pyruvate to fructose

Answer: b

9- Formation of one molecule of glucose from pyruvate requires:

a. 4 ATP, 2 GTP and 2 NADH

b. 3 ATP, 2 GTP and 2 NADH

c. 4 ATP, 1 GTP and 2 NADH

d. 2 ATP, 2 GTP and 2 NADH

Answer: a

10- What is the main source of glucose carbons for gluconeogenesis?

a. Guanine

b. Alanine

c. Cysteine d. Threonine

Answer: b

11- Which of the following statements about gluconeogenesis is correct?

a. Pyruvate is first converted to phosphoenolpyruvate by phosphoenol pyruvate carboxykinase

b. Fructose 1, 6-biphosphatase converts fructose 1, 6-bisphosphate into fructose 1 phosphate

c. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate to release glucose into the blood

d. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate and is found in liver and muscle

Answer: c

12- Gluconeogenesis responds to which of the following?

a. Hormonal control

b. pH control

c. Temperature control d. Blood control

Answer: a

13- When blood sugar levels fall, glycolysis is halted in liver to allow:

a. Homeostasis

b. Anaerobic respiration

c. Aerobic respiration d. Gluconeogenesis

Answer: d 14- How many steps are catalyzed by the same enzymes in both glycolysis and gluconeogenesis?

a. 6 b. 7 c. 8 d. 9 Answer: b

15- Gluconeogenesis:

a. Is favored when insulin concentration is high b. Occurs in the liver during prolonged fasting c. Allows skeletal muscle to produce glucose for export to blood for use by the CNS

d. Is stimulated by high levels of glucose-6-phosphate e) Uses Acetyl CoA as substrate

Answer: b

16- Pyruvate carboxylase:

a. Converts acetyl CoA to pyruvate

b. Requires carnitine

c. Converts pyruvate to oxaloacetate

d. Is activated by high fructose 1,6 bisphosphate e) Requires pyridoxal phosphate

Answer: c

17- Synthesis of glucose from pyruvate by gluconeogenesis in the liver:

a. Occurs exclusively in the cytosol

b. Is inhibited during prolonged fasting

c. Requires participation of biotin

d. Requires lactate as intermediate e. Occurs exclusively in the mitochondrion

Answer: c

18- Pyruvate is:

a. Converted to acetyl CoA by pyruvate carboxylase

b. Four-carbon compound

c. Converted to oxaloacetate by pyruvate dehydrogenase complex

d. Converted to alanine by transamination

e. Intermediate in the TCA cycle

Answer: d

19- The following is present in the liver, but is absent in muscles:

a. Pyruvate carboxylase

b. Glycogen synthase

c. Lactate dehydrogenase d. Pyruvate dehydrogenase

e. Glucose-6-phosphatase

Answer: e

20- In gluconeogenesis:

a. Pyruvate is converted to acetyl CoA

b. Valine and Leucine are substrates

c. Energy consumption is high

d. Insulin is needed to enhance the synthesis of glucose e) Acetyl CoA is a substrate

Answer: c

21- Gluconeogenesis:

a. Is the reversal of glycolysis

b. Is active during prolonged fasting

c. Requires participation of carnitine d. Uses acetate as substrate e. Is very active in the fed state

Answer: b 22- The following enzymes are absent in muscles but are present in the liver:

a. Pyruvate carboxylase and citrate synthase

b. Glucose-6-phosphatase and glycerol kinase

c. Lactate dehydrogenase and isocitrate dehydrogenase d. Pyruvate dehydrogenase and beta-ketothiolase e) Glycogen synthase and 3HMG CoA synthase

Answer: b 23- Name the pathway for glucose synthesis by non-carbohydrate precursors?

a. Glycogenesis b. Glycolysis c. Gluconeogenesis d. Glycogenolysis

Answer: c 24- What is the site for gluconeogenesis?

a. Liver b. Blood c. Muscles d. Brain

Answer: a

25- Which of the following is not the precursor of gluconeogenesis?

a. Glycolytic products

b. Citric acid cycle intermediates

c. Glucogenic amino acid d. Lysine or leucine

Answer: d 26- Name the enzyme which is responsible for the conversion of pyruvate to phosphoenolpyruvate (PEP)?

a. Pyruvate carboxylase b. Pyruvate carboxykinase c. Glucose 6-phosphatase d. Phosphofructokinase

Answer: b 27- Gluconeogenesis is also carried out in muscle and brain: a. True b. False

Answer: b 28- Which of the following hormone maintain blood glucose level by activation of gluconeogenesis?

a. Nor-epinephrine b. Glucagon c. Insulin d. Epinephrine

Answer: b

Lipid chemistry 13

Previous exams & Formatives:

1- Lipids are formed from:

a. Amino acids only b. Fatty acids only c. Alcohol and fatty acids combined by ester bond d. Alcohol and fatty acids combined by peptide bond

2- Cholesteryl palmitate is an example of:

a. Compound lipids b. Derived lipids c. Fatty alcohols d. waxes

3- Sphingosine is: a. Monohydric alcohol b. Trihydric alcohol c. Fatty acid d. Compound lipid

4- Glycerol is:

a. Monohydric alcohol b. trihydric alcohol c. simple lipid d. fatty acid

b. Palmitic

c. Oleic d. Stearic e. Propionic

10- A fatty acid which is not synthesized in human body and has to be supplied in the diet is:

a. Palmitic acid b. Oleic acid c. Stearic acid d. Linoleic acid

11- Which out of the following alcohols is used for waxes:

a. Sphingosine

b. Both cholesterol and long chain is correct c. Glycerol d. Long chain Alcohol e. Cholesterol

12- All are non-essential fatty acids except:

a. Palmitic acid b. Stearic acid c. Oleic acid d. Linolenic

13- Which out of the following is a fatty acid with 16 carbon atoms and one double bond?

a. Palmitoleic acid b. Erucic acid c. Elaidic acid d. Stearic acid 14- A fatty acid which is not synthesized in human body and has to be supplied in the diet is:

a. Linoleic acid b. Palmitic acid c. Oleic acid d. Stearic acid 15- Choose out of the following, a fatty acid with 20 carbon atoms and four double bonds:

a. Timindolic acid b. Nervonic acid c. Arachidonic acid d. Clupanodonic acid 9-a 10-d 11-b 12-d 13-a 14-a 15-c

Extra: 1- Which of the following is a non-glyceride lipid? a. Phospholipids b. Fats c. Oils d.Waxes

2- Which of the following is true regarding saturated fatty acids?

a. double bonds are absent

b. loosely packed

c. low melting point

d. liquid at room temperatures

3- Which of the following statement is true regarding waxes?

a. made up of long fatty acid chains esterified to long-chain alcohols

b. hydrophobic in nature

c. Present on leaf surface and bird feathers

d. all of the above

4- Glycolipids are:

a. Sugar lipid complexes joined by glycosidic bond

b. protein lipid complexes joined by peptide bond

c. Sugar protein complexes joined by glycosidic bond

d. Sugar lipid complexes joined by ester bond

5- At room temperature an unsaturated fatty acid will have:

a. Liquid consistency

b. Solid consistency

c. Waxy consistency

d. Cannot be predicted

1-d 2-a 3-d 4-a 5-a

6- Chemically, fats and oils are:

a. Acids

b. Alcohols

c. Esters

d. Alkenes

7- Which out of the following is not a Glycerophospholipid?

a. Lecithin

b. Cardiolipin c. Sphingomyelin d. Plasmalogen

8- Which of the following is false about lipids?

a. They are either strongly hydrophobic or amphipathic. b. They are more soluble in water.

c. Extraction of lipids from tissues require organic solvents. d. They are insoluble in water.

9- Which of the following form of lipids are also referred as neutral lipids?

a. Triacylglycerol. b. Steroid. c. Phospholipids. d. Wax.

10- What is the solubility of lipids in water?

a. Soluble.

b. Partially soluble. c. Insoluble. d. Partially insoluble.

11- Which one is right about Glycerol:

a. Soluble starch.

b. Soluble in water. c. Insoluble in water. d. Deposited around kidneys and under the skin.

12- Glycerol can be formed through digestion of:

a. Galactose. b. Fats. c. Glucose. d. Sucrose.

13- Dehydration of glycerol gives:

a. Propane. b. Propene. c. Acrolein. d. Benzene.

14- Which of the following is a storage form of lipid?

a. Glycolipid. b. Phospholipid. c. Sulfolipid. d. Triacyl glycerol.

6-c 7-c 8-b 9-a 10-c 11-b 12-b 13-c 14-d

15- Which of the following is not a derived lipid?

a. Arachidonic acid.

b. Diacyl glycerol.

c. HDL.

d. Vitamin D.

16- Glycerol is required for the formation of all of the following compounds except:

a. Glucose.

b. Triacyl glycerol.

c. Phospholipids. d. Glycolipids.

17- Choose a lipid that acts as a precursor for Glycerophospholipids:

a. Cholesterol.

b. Sphingosine.

c. N-Acetyl Neuraminic acid.

d. Phosphatidic acid.

15-c 16-d 17-d

Lipolysis & B-oxidation of fatty acids

Previous exams & Formative:

1- Which of the following is NOT involved in beta-oxidation of fatty acids steps?

a. Reduction b. Hydration c. Splitting of active acetate d. Dehydrogenation

e. Activation of fatty acid

2- How many acetyl CoA groups are produced by the complete β oxidation of palmitic acid (C16)?

a. 16 b. 8 c. 7 d. 20

3- How many oxidation cycles are necessary to completely oxidize palmitic acid (C16)?

a. 16 b. 8 c. 20 d. 7

4- The following hormones increase the mobilization of depot fat (lipolysis) EXCEPT:

a. Epinephrine and nor epinephrine b. Insulin c. Growth hormone d. Glucagon

5- Which of the following compounds is involved in the transport of long chain fatty acids into the mitochondrion:

a. Oxaloacetate

b. Citrate

c. Carnitine

d. Taurine

6- Activation of the fatty acid occur in:

a. mitochondria

b. nucleus c. cytoplasm d. non of the above

7- Lipolysis produce:

a. glycerol and cholesterol

b. glycerol and fatty acid

c. glycerol and ketone bodies d. all of the above

8- which of the following regulates lipolysis in adipocytes?

a. Activation of fatty acid synthesis mediated by CAMP

b. Glycerol phosphorylation to prevent futile esterification of fatty acids

c. Activation of triglyceride lipase as a result of hormone stimulated increase in CAMP levels

d. Activation of CAMP production by insulin

9- Fatty acids enter the mitochondrial matrix for oxidation:

a. In the form of acyl-CoA directly by active transport

b. As free fatty acid

c. Following conversion to carnitine

d. Complexed with carnitine as acyl-carnitines

10- which of the following statements describes best the function of cranitine?

a. It transports medium-chain fatty acid into gut-epithelial cells

b. It transports medium-chain fatty acid across the inner mitochondrial membrane

c. It is a trans-acylayion reaction catalyzed by transferase d. It is a derivative of vitamin A

1-a 2-b 3-d 4- 5-c 6- 7- 8-c 9-d 10-c

Extra:

1- what is the enzyme responsible for the breakdown of triglycerides into fatty acids and mono-acylglycerol in the intestine?

a. Pancreatic lipase b. Lipoprotein lipase

c. Hormone-sensitive lipase d. phospholipase

2- which of the following hormone isn't used in the hydrolysis of triacylglycerol into the fatty acids in adipose tissue?

a. Epinephrine b. Norepinephrine c. Glucagon d. Insulin

3- Excessive lipolysis occurs in

a. Feeding state

b. Diabetes mellitus

c. High carbohydrate diet d. All of the above 1-c 2-d 3-b

4- What are the function of dietary fat?

a. Provide energy to the body b. Part of cellular membrane c. Signaling d. All options given are correct

5- Glycerol released from adipose tissue by hydrolysis of triglycerides is mainly:

a. Utilized by the mscles b. Reutilized in adipose tissue c. Excreted from the body d. Taken up by the liver

6- One of the following inhibits β-oxidation of fatty acid a. AMP b. ATP c. Glucagon d. Adrenaline

7- β-oxidation of fatty acids is dependent on all the following ,Except: a. Activation of fatty acids in cytosol b. Presence of carnitine c. Presence of oxygen d. Supply of NADPH.H+

8- β-oxidation of fatty acids is dependent on the presence of all the following enzymes ,Except:

a. Acyl CoA dehydrogenase b. Enoyl CoA hydratase c. β hydroxyacyl CoA dehydrogenase d. Acetyl CoA carboxylase

Ketogensis and ketolysis

Previous Exams & Formatives:

1- Which of the following is required for utilization of acetoacetate by extrahepatic tissues?

a. Acetyl-CoA

b. Succinyl CoA c. Propionyl-CoA d. HMG-CoA

2-Absence of which of the following causes inability of the liver to use ketone bodies as an energy source?

a. Thiophorase b. Thiolase c. β- hydroxybutyrate dehydrogenase d. Succinate dehydrogenase

3-Hepatocytes deliver ketone bodies to the circulation because they lack which of the following enzymes?

a. beta-hydroxybutyrate dehydrogenase b. succinyl-CoA-acetoacetate-CoAtransferase c. hydroxymethylglutaryl-CoA-synthetase d. hydroxymethylglutaryl-CoA-lyase

4-All of the following metabolic pathways are active after eating large amounts of carbohydrates in normal healthy person

EXCEPT:

a. Glycolysis b. Ketogenesis c. Glycogenesis d. Kreb's cycle

5-A student finished eating a well-balanced meal just 1 hour ago and has since been sitting quietly watching television. Which of the following substances would NOT be elevated in this student’s blood?

a. Acetoacetic acid b. Glucose c. Fatty acid d. Amino acids

6-What is the outcome of the accumulation of acetyl CoA in the mitochondria of the liver ?

a. It is used as an energy source b. It has been broken down into fatty acids c. It gets converted into oxaloacetate d. It forms ketone bodies

7- Ketone bodies are synthesized in:

a. Adipose tissue b. Liver c. Muscles d. Brain

8- All the following statements about ketone bodies are true except:

a. Their synthesis increases in diabetes milletus b. They are synthesized in mitochondria c. They can deplete the alkali reserve d. They can be oxidized in the liver

1-b 2-a 3-b 4-b 5-a 6-c 7-b 8-d

9-All of the following tissue are capable of using ketone bodies except:

a. Skeletal muscles

b. Renal cortex c. RBCs d. Cardiac cells

Answer: c

Extra Questions:

1- what is ketogenesis?

a. Generation of acetyl-CoA from ketone bodies b. Generation of ketone bodies from acetyl-CoA c. Generation of acyl-CoA from ketone bodies d. Generation of ketone bodies from acyl-CoA

2-Which structure is included in ketone bodies?

a. Acetone b. Acetoacetate c. Beta hydroxyl butyrate d. All of the above

3-What Is the location of ketogenesis?

4-Which of the following is a volatile substance?

butyrate d. Acetoacetate

5-Which of the following is not the significance of ketogenesis? a. Supply energy to brain cells b. Metabolize excess of acetyl-CoA c. Supply energy in absence of carbohydrate d. None of the above

6-. ………the increased levels of ketone bodies in blood above the normal level a. Ketosis b. Ketoacidosis c. Ketolysis d. Ketogensis

8-Ketosis leading to……….. a. Ketonemia b. Ketonuria c. All of the above d. None of the above

10-Oxidation of B-hydroxybutyrate yields……… mol of ATP

a. 21.5 b. 32.5 c. 26 d. 20

11-Urine of a person contains abnormal quantities of ____ during prolonged fasting.

a. amino acids b. ketones c. glucose d. fats

10-a 11-b

Lipogenesis

Previous exams & Formative:

1- Acetyl-CoA Carboxylase is activted by?

a. Palmitoyl CoA b. Carbon dioxide c. Citrate d. Malonyl CoA

2- For Denovoa synthesis of fatty Acid, the coenzyme required is?

a. NADH b. NADPH c. Thymine pyrophosphate d. FADH2

3- Which is the allosteric regulator of Acetyl CoA Carboxylase?

a. Fatty Acid b. ATP c. Citrate d. Acetyl CoA

4- Which is the precursor of fatty acid synthesis?

a. Acetyl CoA b. Propionyl CoA c. Succinyl CoA d. Acetoacetyl CoA

5- Which fatty acid contain 16 carbon skeleton?

a. Palmitic Acid b. Glumatic Acid

c. Lauric Acid d. Myristic Acid

6- Which one of the follwing is an essential Fatty Acid?

a. Linolenic acid b. Palmitic Acid c. Linoleic acid d. Both (a)&(c)

7- Which of the follwing is an Saturated fatty Acid?

4- Synthesis of fatty Acid begin which from compound? a. Acyl CoA b. Acetyl CoA c. Phospholipid d. Lipoproteins

5- Which of energy is required for conversion of Acetyl CoA to malonyl CoA? a. NADH b. GTP c. AMP d. None of the above 6- The rate limiting enzyme regulating the denevo synthesis of fatty Acid is? a. Thioestrase b. Enol reductase c. Ketoacyl synthase d. Acetyl CoA carboxylase 7- Which of the following statement is not true? a. Lipogenesis is same as lipolysis b. Fatty acid is synthesized from acetyl CoA c. Insulin activates acetyl CoA carboxylase d. Glucagon inhibits the acetyl CoA carboxylase 8- which of the follwing stimulate fatty Acid synthesis? a. Citrate

b. Insulin c. Long chain acyl CoA d. Both b & c e. Both a & c 9- Presence of insulin lead to…….and……..of acetyl CoA Carboxylase enzyme? a. Phosphorylation & Activation b. Dephosorylation & Inhibition c. Phosphorylation & inhibition d. Dephosphorylation & activation 10- Which of the following is second step in lipogenesis? a. Transport of Acetyl CoA from mitochondria to cytosol b. Carboxylation of Acetyl CoA to malonyl CoA c. Reactions of synthesis using fatty Acid synthase complex d. None of the above 1-c 2-a 3-d 4-b 5-d 6-d 7-a 8-e 9-d 10-b 11- Conversion of acetyl CoA to malonyl CoA requires which of the follwing? a. NADPH b. H2o c. Folic acid d. Biotin 12- In what compartments does the Denovo fatty acid synthesis? a. Mitochondria b. Perixomes c. Endoplasmic reticulum d. Cytosol

c. Both d. None of the above 18- Identify the correct sequential enzymatic step for fatty Acid synthesis?

a. Dela-2- enoyl coA dehydrate, Acyl CoA dehydrogenase, hydroxy Acyl dehydrogenase, thiolase

b. Hydroxy aceyl dehydrogenase, Acyl CoA dehydrogenase, delta-2-enoyl coA dehydrate, thiolase

c. Thiolase, Acyl CoA dehydrogenase, delta-2- enoyl CoA dehydrate hydroxy Acyl CoA dehydrogenase

d. Acyl CoA dehydrogenase, delta-2- enoyl CoA dehydrate, hydroxy Acyl dehydrogenase, thiolase

19- Which of the follwing inhibit Acetyl CoA Carboxylase a rate limiting enzyme of fatty Acid metabolism?

a. Citrate b. ATP c. Malonyl CoA d. Acyl CoA 20- Chain elongation of fatty Acid take place in which of the follwing subcellular fractions?

a. Cytoplasm b. Nucleus c. Mitochondria d. Golgi complex 11-d 1 2-d 1 3-d 14-a 1 5-c 16-d 1 7-c 18-d 19-d 20-c

21- Source of NADPH for fatty Acid synthesis include all the follwing except?

a. Glucose-6- phosphate dehydrogenase

b. Cytoplasmic isocitrate dehydrogenase c. 6- phospho- gluconate dehydrogenase d. Cytoplasmic malate dehydrogenase

22- All of the follwing about process of fatty Acid biosynthesis are true except?

a. It occurs in cytosol b. It requires NADPH c. It requires biotin d. It requires FADH2

23- Fatty Acid synthesis differs from beta oxidation in all except?

a. Catalyzed by multienzyme complex b. Required NADPH as reducing power c. Requires Co enzyme A d. Activated by insulin 24- Biotin is co enzyme for?

a. Transaminases b. Carboxylase c. Decarboxylase d. Oxidation

25- How many enzymatic sites does fatty Acid synthase complex have?

a. 8 b. 6 c. 7 d. 5

26- Which of the following is not required in synthesis of fatty Acid?

a. Acetyl CoA b. Biotin c. Ca d. NADH e. None of the above 27- Which of the following is not true of reaction producing malonyl CoA during fatty Acid synthesis?

a. It's stimulated by citrate b. It requires Acyl carrier protein (ACP) c. It requires co2 or (bicarbonate) d. One mole of ATP is converted to ADP +pi for each malonyl CoA synthesized e. The cofactor is biotin 28- Cholesterol is synthesized from?

a. Acetyl CoA b. Choline c. Lipoic Acid d. Malate e. Oxalate 29- Which of the follwing reduce double bond forming Saturated Acyl ACP? a. B-ketoacyl ACP reductase b. B-hydroxyacyl ACP dehydratase c. Enoyl ACP reductase d. Malonyl CoA ACP transferase 30- Which of the follwing enzyme is not used in synthesis of triacylglycerol?

a. Glucose-3- phosphate Acyltransferase b. Acylglycerophosphate Acyltransferase

21-d 22-d 23- c 24-b 25-c 26-c 27-b 28-a 29-c 30-d

Nitrogen metabolism 17

Previous exams & Formatives:

5- The main site of urea synthesis in mammals: a. Liver b. Skin c. Intestine d. Kidney 6- Removal of amino group from amino acids to α keto acids called: a. Transamination b. Deamination c. Trans-deamination d. Trans methylation 7- Major pathway of nitrogen excretion in man is as: a. Creatine b. Urea c. Both a, b d. Ammonia 8- Principal pathway of disposal ammonia is: a. Urea formation b. Glutamine synthesis c. None of the above d. A and b 1-a 2-b 3-a 4-a 5-a 6-a 7-b 8-a

9- Citrullinemia is a type of inherited hyperammonemia resulting from inherited deficiency of:

a. Citrulline synthase

b. Arginosuccinate synthase

c. Ornithine transcarbamoylase d. Carbamoyl phosphate synthase

10- Urea production occurs almost exclusively in:

a. Kidneys b. Liver c. Blood d. Urine

11- The first amino group entering into urea cycle is:

a. Carbamoyl phosphate b. Ornithine c. Citrulline d. Arginosuccinate

12- The reaction of glutamate and NH4+ to yield glutamine is catalyzed by:

a. Uridyl transferase b. Adenyl transferase c. Glutamate synthase d. Glutamine synthase

13- An intermediate of the citric acid cycle that undergoes reductive amination with glutamine as nitrogen donor is:

a. α-ketoglutarate

b. Glutamine c. NADPH d. H+ e. Succinyl CoA 14- Urea is produced physiologically by the action of the enzyme: a. Urease b. Glutaminase c. Arginase d. None of these 15- The biosynthesis of urea occurs mainly in the liver: a. Cytosol b. Mitochondria c. Microsomes d. Nuclei 9-b 10-b 11-a 12-d 13-a 14-c 15-b

Extra: 1- The first enzyme in the pathway carbamoyl phosphate synthase I, is allosterically activated by: a. N-acetyl glutamate b. Acetyl CoA c. Glutamate d. Carbamoyl phosphate

2- A second amino group is transferred to citrulline from:

a. Aspartate

b. Glutamate c. Alanine d. Guanine

3- What are the products of urea cycle?

a. One molecule of urea, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid

b. One molecule of urea, one molecule of AMP, two molecules of ADP and one molecule of fumaric acid

c. One molecule of aspartic acid, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid

d. Two molecules of urea, two molecules of ammonia, one molecule of ATP and one molecule of fumaric acid

4- The carbon atom source while producing urea in the urea cycle is:

a. CO 2 b. Glucose c. Aspartic acid d. Arginine

5- What are the inputs to one cycle of urea cycle?

a. One molecule of CO 2 , one molecule of ammonia, three molecules of ATP and one molecule of aspartic acid

b. One molecule of urea, one molecule of AMP, two molecules of ADP and one molecule of fumaric acid

c. One molecule of aspartic acid, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid

d. Two molecules of urea, two molecules of ammonia, one molecule of ATP and one molecule of fumaric acid

6- Glutamate is metabolically converted to α-ketoglutarate and NH 4+ by a process called: a. Oxidative deamination b. Transamination c. Reductive deamination d. Deamination

7- Pyridoxal phosphate and its aminate form, pyridoxamine phosphate are tightly bound coenzymes of: a. Amino transferases b. Glutaminase c. Glutamine synthase d. Glutamate dehydrogenase

8- What is the need for the conversion of ammonia in other metabolites?

a. It is toxic in nature b. It cannot mix with other components of urine c. Both d. None 1-a 2-a 3-b 4-a 5-a 6-a 7-a 8-a

9- In which form, the ammonia is transported into the blood?

a. Alanine

b. Pyruvate c. Glutamine d. Both A and c 10- In which tissue, ammonia combines with glutamate?

a. Kidney b. Brain c. Liver d. All of the above 11- Which of the following compound is major storage form of ammonia?

a. Alanine b. Pyruvate c. Glucose d. Glutamine 9-d 10-d 11-d

Decarboxylation of amino acids

Previous exams & Formative: molecules derived from amino acids

1- GABA is derived from Glutamate by which of the following reactions?

a. Decarboxylation b. Transamination c. Dehydrogenation d. Hydroxylation

2- All the following are products of phenylalanine except?

a. Thyroxine b. Melanin c. Serotonin d. Adrenaline & Noradrenaline

3- Precursor for nitric oxide?

a. Arginine b. Leucine c. Isoleucine d. Lysine

4- We can obtain of melanin pigment?

a. Tyrosine b. Sulfur containing amino acid c. Both of them d. None of the above 1-a 2-c 3-a 4-c

10- Decarboxylation of histidine gives?

a. Histamine

b. Adrenaline

c. None of the above d. Hormones

11- Decarboxylation of glutamic acid produces?

a. Gamma-aminobutyric acid b. Aceto-acetic acid c. Both a & b d. Glutamine

12- Normal serum creatinine level?

a. 0,2-0.4 mg/dl b. 0,3-0,6 mg/dl c. 0,7-1,4 mg/dl d. 1,4-2,8 mg/dl

13- Creatinine is synthesized from the following amino acid except?

a. Arginine b. Aspartic acid c. Glycine d. Methionine

10-a 11-a 12-c 13-b

Extra

1- Which of the following is derived from tryptophan?

a. Dopamine

b. Norepinephrine

c. Epinephrine d. Serotonin

2- Cimetidine is a structural analog of?

a. Proline b. Tryptophan c. Tyrosine d. Histamine

3- Tyrosine is a nutritionally non-essential amino acid that is synthesized from phenylalanine. Identify the enzyme responsible catalyzes the reaction?

a. Tyrosine deaminase b. Tyrosinase c. Tyrosine Hydroxylase d. Phenylalanine Hydroxylase 4- Phenylalanine hydroxylase (PAH) is an enzyme that required the reduced form of the following co-factor for its activity?

a. NADH b. NADPH c. Reduced Glutathione d. Reduce tetrahydrobiopterin

5- The conversion of norepinephrine to epinephrine is catalyzed by phenyl ethanolamine N-methyl transferase. Which of the following metabolic intermediate serve as a methyl donor?

a. S-adenosyl cysteine b. S-adenosyl methionine c. Alanine d. Acetyl CoA 1-d 2-d 3-d 4-d 5-b

11- One of the following statements regarding serotonin is true?

a. It causes vasodilatation.

b. It causes albinism.

c. It is an antioxidant

d. It acts as a vasoconstrictor

12- Tyrosine is?

a. An essential amino acid

b. A precursor in the biosynthesis of serotonin

c. A precursor in the biosynthesis of γ-aminobutyric acid (GABA)

d. Both gluconeogenic and ketogenic

11-d 12-d

19 Disorders of Tyrosine

Previous exams & Formative:

1- Deficiency of homogentisic oxygenase enzyme leads to:

a. Leukoderma

b. Alkaptonuria

c. Both of them d.None of the above

2- End metabolic product used in diagnosis of pheochromocytoma is:

a. Van mandlic acid b. catecholamines

c. Both of them d. None of the above

3- Deficiency of phenyl alanine hydroxylase enzyme cause:

a. Alkaptonuria

b. Phenylketonuria

c. Both a and b d. Favism

4- All the following are true about phenylketonuria except:

a. Deficiency of phenylalanine hydroxylase

b. Decrease serotonin formation

c. Increased urinary excretion of p-hydroxyphenyl pyruvic acid

d. Mental retardation

1-b 2-a 3-b 4-b

Extra:

1- Which one of the following is the Most common disease of amino acids metabolism?

a. Homocystinuria

b.Albinism

c. Phenylketonuria

d. Maple Syrup Urine Disease

2- Which of these is a hereditary disease caused due to an error in amino acid metabolism?

a. Homocystinuria

b. Albinism

c. Phenylketonuria

d. Branched-chain ketoaciduria

3- Phenylketonuria is a genetic disorder caused by a deficiency of an enzyme that converts phenylalanine to tyrosine. Identify the correct statements regarding phenylketonuria:

a. PKU occurs due to deficiency of both PAH and dihydrobiopterin reductase deficiency

b. Missense mutation of the PAH gene are frequently observed in PKU patients

c. All PKU patients do not respond to biopterin treatment

d. None of the above

e. a and b

4- The following are phenyl ketones found in the PKU patients except: a. Phenylacetate b. Phenyl-lactate c. Phenyl pyruvate d. Phenyl succinate 5- Tyrosinemia-I is a genetic disorder caused by the deficiency of: a. Fumaryl-Acetoacetate hydrolase b. Tyrosine Aminotransferase c. Hydroxyphenylalainine pyruvate d. Homogentisate oxidase

6- Tyrosinemia-II is a genetic disorder caused by the deficiency of:

a. Fumaryl-Acetoacetate hydrolase b. Tyrosine Aminotransferase c. Hydroxyphenylalainine pyruvate hydroxylase d. Homogentisate oxidase 7- Alkaptonuria is a genetic disorder caused by the deficiency of: a. Fumaryl-Acetoacetase b. Tyrosine Aminotransferase c. Hydroxyphenylalainine pyruvate hydroxylase d. Homogentisate oxidase 1-c 2-c 3-e 4-d 5-a 6-b 7-d 8- Neonatal Tyrosinemia is a genetic disorder caused by the deficiency of:

a. Fumaryl-Acetoacetase

b. Tyrosine Aminotransferase c. Hydroxyphenylalainine pyruvate hydroxylase d. Homogentisate oxidase

9- Which one of the following statements concerning a one-week-old male infant with undetected classic phenylketonuria is correct?

a. Tyrosine is a non-essential an amino acid for the infant b. High levels of phenylpyruvate appear in the urine c. A diet devoid of phenylalanine should be initiated immediately d. Therapy must begin within the first year of life.

10- Tyrosinemia Type I is caused by a deficiency of fumarylacetoacetate hydrolase. All the following statement are true for this disease except: a. Accumulation of Tyrosine in blood b. Increased Urinary Homogentisate c. Increased succinyl acetone d. Increased methionine

11- Which of the following analyte is used for the diagnosis of alkaptonuria?

a. Phenylacetate b. Homogentisate c. p-Hyroxyphenylacetate d. Fumarylacetoacetate 8-c 9-b 10-b 11-b

Metabolism of individual Amino acids

Previous exams & formative:

1- One of these amino acids do not enter in glutathione structure:

a. Glycine b. Serine c. Cysteine d. Glutamate

2- One of these amino acids do not enter in Creatine structure: a. Glycine b. Arginine c. Methionine d. Histidine

3- Glutathione is: a. Tripeptide b. Dipeptide c. Polypeptide d. Polypeptide

4- Glycine enters in formation of:

a. Glutathione b. Bile salts c. Both a & b d. Estrogen

Answers: 1-b 2-d 3-a 4-c

5- Glutathione is:

a. Tripeptide formed of 3 amino acids b. Exists in 2 forms c. Both a & b d. Dipeptide

6- Glycine is characterized by:

a. Absence of an asymmetric carbon b. Absence of optical activity c. The shortest amino acid d. All of these

Answers: 5-a 6-d Extra:

1- Glycine is not required for the formation of Select one: a. Creatine b. Taurocholic acid c. Pyrimidines d. Purines

2- Creatine synthesis requires all of the following amino acids, except: Select one:

a. Glycine b. Methionine c. Arginine d. Ornithine

Answers: 1-c 2-d

3- Collagen contains high percentage of:

a. Glycine

b. Tryptophan

c. Phenylalanine

d. Serine

4- Glycine is:

a. A non-optically active amino acid b. Present in structure of glutathione c. A neutral amino acid d. All of these

5-With the exception of glycine, all amino acids found in proteins are:

a. Optically active b. Dextrorotatory c. Of l-configuration d. Levorotatory

6- Glycine and proline are the most abundant amino acids in which of the following structure?

a. Hemoglobin b. Myoglobin c. Insulin d. Collagen

Answers: 3-a 4-d 5-a 6-d

7- Among the listed amino acids, which one is non-polar?

a. Lysine b. Serine c. Histidine d. Glycine 8- Which of the following amino acid shows hydrophilic nature?

a. Leucine

b. Glycine

c. Valine d. Serine

9- Precursor of glycine is ________

a. Proline b. Glutamine c. Serine d. Glutamate

10- Out of the following, amino acids with hydroxyl groups are:

a. Serine and alanine b. Alanine and Valine c. Serine and threonine d. Valine and Isoleucine

Answer: 7-d 8-d 9-c 10-c

11- Which of the following amino acids is sweet in taste?

a. Glycine b. Alanine c. Glutamic acid d. None of these

12- The conversion of serine to glycine is catalyzed by an enzyme serine hydroxy methyltransferase. The co-substrate required for this reaction is:

a. Biotin

b. Pyridoxal Phosphate c. Tetrahydrobiopterin d. Tetrahydrofolate

13- In mammalian tissue serine can be a biosynthetic precursor for which amino acid?

a. Methionine

b. Glycine

c. Arginine

d. Lysine

14- Chose the incorrect statement about amino acid Glycine:

a. One carbon donor

b. Required for the synthesis of haem

c. Forms oxalates upon catabolism

d. Both glucogenic as well as ketogenic

Answer: 11-a 12-c 13-b 14-d

Structure of nucleic acids

Previous exams and formative:

1- All of The Following Are Purine Bases Except:

a. Adenine b. Guanine c. Cytosine d. All Of The Above

2- Gout is a disease characterized by increase in serum ...... a. Bile Acids b. Uric Acid c. Urea d. Creatinine 3- An Example of Nucleoside is:

a. C AMP b. ATP c. AMP d. Adenosine 4- Most predominant protein associated with chromatin is: a. Ubiquitin b. Nucleoplasmin c. DNA ligase d. Histone

5- Nucleotide is formed of:

a. Base, sugar and phosphate group b. Base, and phosphate group

c. Base and sugar d. Base, sugar and sulfate group

6- Histones are small proteins formed from: a. Arginine and glycine b. Arginine and tyrosine c. Arginine and histidine d. Arginine only

7- The packaging unit of the chromatin is called: a. Ribosome b. Nucleosome c. Microsome d. Chromosome 8- 1ry metabolic gout is a disease characterized by increased activity of ....... a. HGRPt b. PRPP c. Xanthine oxidase d. None of above Ans: 1-c 2-b 3- d 4-d 5-a 6-c 7-b 8-b

Extra: 1- Which of the following statements is correct with respect to purines?

a. Purines are heterocyclic compounds. b. Purines are 7 membered structure c. Purines are single - ring structure " small structure " d. Thymine is an example of purine

2- Which of the following is DNA made up of?

a. Adenine - Guanine b. Cytosine - Thymine c. Both Adenine - Guanine & Cytosine - Thymine d. None of the mentioned

Ans: 1-a 2-c

3- Which of the following is RNA made up of?

a. Adenine , Cytosine , Guanine , and Uracil b. Adenine , Guanine , Cytosine , and Thymine c. Adenine , Guanine , Uracil , and Thymine d. Adenine , Uracil , Cytosine , and Thymine

4- What are the set of positively charged basic proteins called as?

a. Histidine b. DNA c. RNA d. Histones

5- The sugar molecule in a nucleotide is: a. Pentose b. Hexose c. Tetrose d. Triose

6- In Nucleic acid, nucleotides are linked to each other by: a. 3,5 phosphodiester bond b. Ester bond c. Glycosidic bond d. None of the above 7- Chromatin is composed of:

a. Proteins Only

b. Nucleic Acids Only

c. Nucleic Acids and Protein

d. None Of These

8- Adjacent nucleotides are joined by

a. Phosphodiester Bond

b. Covalent Bond c. Ionic Bond d. none of the above

Ans: 3-d 4-d 5-a 6-a 7-c 8-a

9- The following are the sources of different atoms of purine bases

EXCEPT:

a. Aspartate b. Glutamate c. Tetrahydrofolate d. Respiratory CO2

10- The following are the sources of different atoms of pyrimidine bases EXCEPT:

a. Aspartate b. Glutamine c. Asparagine d. Respiratory CO2

11- PRPP is important in:

a. de novo synthesis of purine nucleotides

b. Purine salvage pathway c. Synthesis of pyrimidine nucleotides d. All of the above

12- Lesch Nyhan syndrome is due to deficiency of:

a. PRPP synthetase

b. HGPR transferase

c. APR transferase d. IMP dehydrogenase

13- The formation of uric acid from purines is catalyzed by:

a. Adenylate deaminase b. Uricase c. Allantoinase d. Urease e. Xanthine oxidase

14- The key substance in pyrimidine biosynthesis is :

a. Carbamoyl phosphate b. Thiouracil c. ATP d. NADP +

15- The end product of purine metabolism that is excreted by man is:

a. Allantoic acid b. Orotic acid c. Urea d. Uric acid

Ans: 9-b 10-c 11-a 12-b 13-e 14-a 15-d

DNA replication 23

Previous exams & Formative:

1- Replication of DNA in eukaryotes is catalyzed by

a. DNA polymerase Ill

b. DNA polymerase 8 c. DNA polymerase a d. DNA polymerase ß

2- A 23-year-old man is referred to an oncologist, who begins treatment with the topoisomerase inhibitor etoposide. The normal function of this enzyme is to do which of the following

a. Synthesize RNA primers for DNA polymerase b. Break and rejoin the DNA helix during replication c. Repair nuclear DNA in the event of DNA damage d. Unwind the DNA helix during replication e. Prevent the single strands of DNA from reannealing during replication

3- Which enzyme is not required for replication

a. DNA ligase b. Topoisomerase c. Helicase d. Reverse transcriptase

4- Which enzyme is required for separation of double stranded DNA

a. DNA ligase

b. Topoisomerase c. Helicase d. Reverse transcriptase

1-a 2-b 3-d 4-c

5- DNA replication requires all, except:

a. Elongation factors

b. DNA polymerase

c. Deoxynucleotide phosphates d. RNA primer

6- Which enzyme is required for prevention of positive supercoiling of DNA

a. DNA ligase b. Topoisomerase c. Helicase d. Reverse transcriptase

7- Okazaki fragments are small bits of

a. RNA b. DNA with RNA heads c. DNA d. RNA with DNA heads 5-a 6-b 7-c

Extra: 1- which of the following participate in DNA replication

a. DNA polymerases b. DNA helicase c. Primase enzyme d. All of the above

2- Excision of the RNA primers & filling the gaps resulting from removal of the RNA primers by DNA sequences is the function of.........

a. DNA polymerase I b. DNA polymerase II c. DNA polymerase III d. None of the above 1-d 2-a

3- Synthesis of leading strand the function of.......

a. DNA polymerase I

b. DNA polymerase II c. DNA polymerase III d. None of the above

4- DNA proof reading is the function of.......

a. DNA polymerase I b. DNA polymerase II c. DNA polymerase III d. None of the above

5- DNA polymerase α in Eukaryotes act as.......in Prokaryotes

a. DNA polymerase I b. DNA polymerase II c. DNA polymerase III d. None of the above

6- the RNA primer is synthesized by.......

a. DNA polymerase δ b. DNA polymerase α c. DNA polymerase γ d. DNA polymerase Ɛ

7- What is DNA replication?

a. Conservative b. Non-conservative c. Semi-conservative d. None of the mentioned 3-c 4-b 5-c 6-a 7-c

12- Synthesis of lagging strand.........

a. It is built in 3’-5’direction away from the replication fork b. It is built in a discontinuous manner forming okazaki fragments which are small fragments of DNA c. It contains many RNA primers d. All of the above 8-c 9-b 10-b 11-b 12-d

Structure of Ribonucleic acids

Previous exams & Formative:

5- mRNA is complementary to the nucleotide sequence of?

a. Coding strand b. Ribosomal RNA c. tRNA d. Template strand 6- )5’-TATTAT-3’( is a?

a. Hogness box b. Pribnow box c. None of the above d. In replication

7- Name the pyrimidine base which is found in RNA but not in DNA?

a. Thymine b. Uracil c. Adenine d. Guanine

8- Termination of the synthesis of the RNA molecule is signaled by a sequence in the template strand of the DNA molecule, a signal that is recognized by a termination protein, the?

a. Rho factor b. Sigma factor c. δ factor d. є factor

9- Genetic information flows from?

a. DNA to DNA b. DNA to RNA c. RNA to cellular proteins d. DNA to cellular proteins

10- In the process of transcription of bacterial cells?

a. Initiation requires rho protein b. RNA polymerase incorporates methylated c. Both the sigma unit and core enzymes of RNA d. Primase is necessary for initiation

11- 5’-Terminus of mRNA molecule is capped with?

a. Adenosine triphosphate b. Guanosine triphosphate c. Adenosine diphosphate d. 7-Methylguanosine triphosphate

12- In RNE molecule (caps)?

a. Occur at the 3’ end of mRNA b. Are unique to eukaryotic mRNA c. Allow correct translation of prokaryotic mRNA d. Allow tRNA to be processed

Extra:

1- Molecules which play the key role in the transfer of genetic information during protein synthesis are? a. DNA b. RNA c. Nucleic acid d. Lipids

2- Name the RNA molecules which is used to carry genetic information copied from DNA?

a. tRNA b. mRNA c. rRNA d. snRNA 10-c 11-d 12-b 1-b 2-b

3- Name the RNA molecule which takes part in the formation of the ribosome?

a. mRNA b. tRNA c. rRNA d. gRNA

4- What is the main function of t-RNA?

a. Proof reading b. Inhibits protein synthesis

c. Identifies amino acids and transport them to ribosomes d. None of the mentioned

5- Which of the following enzyme binds to the promoter and initiates the process of transcription?

a. DNA polymerase b. Lipase

c. RNA polymerase d. lysozyme

6- Mark the statement which is INCORRECT about the transcription unit?

a. It is a transcribed segment of DNA

b. Eukaryotes have monocistronic transcription unit c. Prokaryotes also have a monocistronic transcription unit d. Immediate product of transcription is primary transcript.

7- Which of the following is untrue?

a. RNA polymerases I is responsible for the transcription of ribosomal RNA b. RNA polymerases III is responsible for the transcription of tRNA

c. RNA polymerase II is exclusively responsible for transcribing proteinencoding genes

d. Synthesis of mRNAs is carried out by RNA polymerase

3-c 4-c 5-c 6-c 7-d

8- In prokaryotes, RNA polymerase catalyzes the synthesis of?

a. mRNA b. rRNA c. tRNA d. All of the above

9- The RNA polymerase is a multi-subunit enzyme that recognizes a consensus nucleotide sequence (promoter region) upstream of the transcription start site. In prokaryotes, the consensus promoter sequence consists of 5-TATAAT-3' also known as:

a. Enhancer box b. Pribnow box c. Transcription unit d. None of the above 10- In eukaryotes, the consensus promoter sequences (TATA box) that are required for initiation of transcription is generally present?

a. 10 nucleotides upstream of transcription start site (TSS) b. 25 nucleotides upstream of TSS c. 10 nucleotides downstream of TSS d. 25 nucleotides downstream of TSS

11- In eukaryotes, the primary transcripts are processed to remove intervening sequence resulting in mRNA and the process is known as splicing. The complex of RNA, nucleoproteins that execute splicing process is called?

a. Primosome b. Splicing fork c. Spliceosome d. None of the above 8-d 9-b 10-b 11-c

Previous exams & Formative:

1- Termination of the synthesis of the RNA molecule is signaled by a sequence in the template strand of the DNA molecule, a signal that is recognized by a termination protein:

a. Rho (p) factor b. σ factor c. δ factor d. ε factor

2- After formation of a peptide bond, mRNA is translocated along the ribosome by Select one:

a. eEF-2 and GTP b. Peptidyl transferase and GTP c. eEF-1 and GTP d. Peptidyl transferase and ATP 1-a 2-a

Extra:

1- Conversion of messages carried by mRNA into amino acid sequences is called:

a. Replication b. DNA repair c. Translation d. Transcription

2- tRNA has peptidyl transferase activity:

a. True b. False 3- The following set of RNA is required in the translation process except one, mark the INCORRECT?

a. Si RNA b. rRNA c. mRNA d. tRNA 4- Which of the following is considered as a start codon?

a. AUG b. GUG c. UAG d. AGG 5- Mark the one, which is NOT a stop codon? a. UAA b. UAG c. UGA d. GGA

6- Which of the following recognize a specific amino acid and its cognate t RNA molecule?

a. t-RNA synthetase b. Ribosome c. r-RNA d. Topoisomerase 2-b 3-a 4-a 5-d 6-a

7- Which of the following is the most energetically costly process among the following:

a. Replication b. Transcription c. Post transcriptional processing d. Translation 8- How many major components are used for the process of translation?

a. 1 b. 2 c. 3 d. 4 9- The amino acids for protein synthesis is activated by the enzyme:

a. RNA synthetase b. aminoacyl-tRNA synthetase c. tRNA synthetase d. aminoacyl-mRNA synthetase 10- The activation of amino acids requires energy. a. True b. False 11- The first amino acid to be incorporated in the eukaryotic polypeptide is:

a. Methionine b. Valine c. N-formyl methionine d. N-acyl valine 7-d 8-d 9-b 10-a 11-a

12- Genetic information stored in mRNA is translated to polypeptide by:

a. Ribosome b. Nucleus c. Endoplasmic reticulum d. Golgi apparatus

13- Eukaryotes have 80S ribosome:

a. True b. False 14- Name the site where secreted protein synthesized?

a. ER membrane bound ribosomes b. Mitochondrial ribosome c. Membrane free ribosome d. Chloroplast ribosome

15- On the ribosome, mRNA binds:

a. Between the subunits b. To the large subunit c. To the small subunit d. None of these 16- The first step in translation is:

a. Binding of the two ribosomal subunits to each other b. B. Binding of mRNA to the two ribosomal subunits c. Binding of tRNA to the small ribosomal subunit d. Binding of mRNA to the small ribosomal subunit

12-a 13-a 14-a 15-c 16-d

17- The growing polypeptide chain is released from the ribosomes when:

a. A chain terminating codon is reached b. A chain terminating tRNA binds to the ribosome c. The 7-methyl guanosine cap is reached d. The poly a tail is reached

18- Which of the following is not a requirement for protein synthesis:

a. Ribosomes b. peptidyl transferase c. Spliceosome d. amino acyl-tRNA synthetase

19- Which is the source of energy for amino acid activation:

a. ATP b. GTP c. CTP d. TTP

20- Which of the following statement is correct:

a. Termination codon has no tRNA b. Activated amino acid binds to the 5’ end of respective tRNA molecule c. CTP is required for amino acid activation d. there is only one amino acyl-tRNA synthetase in a cell

17-a 18-c 19-a 20-a

21- Peptide bond formation between amino acids of growing polypeptide chain is catalyzed by:

a. Peptidyl transferase

b. Amino acyl-tRNA synthetase

c. Peptide polymerase

d. Peptidyl synthetase

22- Peptidyl transferase involved in peptide bond formation is located in the:

a. 3’ region of tRNA b. Smaller subunit of ribosome c. Larger subunit of ribosome d. Near shine Dalgarno sequence 23- The amino acids are assembled into polypeptide chains on:

a. mRNA b. Nucleus c. Ribosome d. DNA template 24- GTP is required by which of the following steps in protein synthesis:

a. Attachment of mRNA to ribosomes

b. Translocation of RNA - nascent protein complex from A to P – sites c. Attachment of ribosomes to endoplasmic reticulum

d. Aminoacyl RNA synthetase activation of amino acids 21-a 22-c 23-c 24-b

DNA Mutations 26

Previous exams & Formative:

1- Which type of anemia represent a point mutation:

a. Iron deficiency anemia

b. Thalassemia

c. Sickle cell anemia d. Precious anemia

2- Mut L enzyme involved in ………. Repair:

a. Mismatch

b. Thymine – thymine dimmer c. a & b d. none of the above

3- Point mutation may produce:

a. Nonfunctioning protein b. Premature stopping of protein chain c. a & b d. None of the above 1-b 2-a 3- c

Extra:

1- If the mutation has a negligible effect on the function of a gene, it is known as a…….

a. Silent mutation b. Frame shift mutation c. Substitution mutation d. Insertion mutation

2- Which of the following mechanisms will remove uracil and incorporate the correct base?

a. Direct repair b. Base excision repair c. Mismatch repair d. Nucleotide excision repair

3- Which of the following has the self-repairing mechanisms? a. DNA and RNA b. DNA, RNA and protein c. Only DNA d. DNA and proteins

4- What is the function of enzyme involved in base excision repair? a. Addition of correct base b. Addition of correct nucleotide c. Removal of incorrect base d. Removal of phosphodiester bond

5- The DNA polymerase involved in base excision repair is ………. a. DNA polymerase α b. DNA polymerase β c. DNA polymerase σ d. DNA polymerase γ

6- An alteration in a nucleotide sequence that changes a triplet coding for an amino acid into a termination codon is …………. a. Nonsense mutation b. Mutagenesis c. Mutation d. Mutagen

7- A point mutation that replaces a purine with another purine, or a pyrimidine with another pyrimidine ………. a. Nonsense mutation b. Silent mutation

c. Transition mutation d. Transversion

8- The enzyme of E. coli is a nuclease that initiates the repair of double stranded DNA breaks by homologous recombination is? a. DNA glycosylase b. DNA ligase c. DNA polymerase d. RNA polymerase 9- Recombinational repair is often due to ………… a. Incorporation of many incorrect nucleotides by DNA pol b. Many cytidines dimer and associated large gaps in a strand c. Many thymidine dimer formations and associated large gaps in a strand d. All of the mentioned 10- The enzyme photolyase is used in what method of repair? a. Base excision b. Photo reactivation c. Nucleotide excision d. None of the mentioned 11- How many kinds of mutation are found in DNA which includes mutation of only one base? a. 1 b. 2 c. 3 d. 4 12- The mutation occurs at a random basis within a genome. a. True b. False 1-a 2-b 3-c 4-c 5-b 6-a 7-c 8-a 9-c 10-b 11-b 12-b

13- By which process miss-incorporated base can change into a permanent mutation?

a. Replication b. b. Transcription c. Translation d. Transposition

14- Detection of mismatches and fidelity of replication is maintained by mutation repair system. a. True b. False 15- How many steps are required to attain mismatch repair? a. 1 b. 3 c. 2 d. 4

16- Mismatch repair system is ATP dependent. a. True b. False

17- High level of mutation in the germ cells is acceptable but in somatic cells can be catastrophic. a. True b. False

18- Point mutation involves:

a. Deletion b. Insertion c. Duplication d. Change in single base pair

13-a 14- a 15-c 16-a 17-b 18-d

19- Gene mutation occurs at time of:

a. DNA repair b. DNA replication c. Cell division d. RNA transcription

20- The action of ultraviolet radiation on DNA to induce mutation is the:

a. Formation of thymine dimers

b. Methylation of base pairs

c. Deletion of base pairs d. Addition of base pairs

21- X Rays cause mutation by

a. Deletion b. Transition c. Transversion d. Base substitution

22- In mutational event, when adenine is replaced by guanine it is a case of:

a. Transition b. Transcription c. Transversion d. Frameshift mutation

19-b 20- a 21- a 22-a

23- An 8-month-old child is suffering from excessive sensitivity to sun, red and scaling of the skin. irregular dark spots have also appeared. the pediatrician suspects a genetic disorder in which of the following processes?

a. Nucleotide excision repair

b. Base excision repair c. Translation d. Transcription e. DNA replication

24- Ultraviolet light can damage a DNA strand causing:

a. two adjacent purine residue to form a covalently bounded dimer b. disruption of non- covalent linkage c. C. two adjacent pyrimidine residues to form covalently bounded dimer d. disruption of phosphodiesterase linkage

25- The defect in base excision repair mechanism is duo to defect in:

a. methylation of the correct strand and GATC endonucleases b. glycosylase

c. Ku and DNA-pk proteins d. UV specific endonuclease 23- a 24- c 25- b

Regulation of Gene expression 27

Previous exams & Formative:

1- The process of formation of RNA is known as:

a. Replication b. DNA repair c. Translation d. Transcription

2- Which of the following ensure stable binding of RNA polymerase at the promoter site?

a. DNA photolyase b. Sigma factor c. DNA glycosylase d. Primase

3- In the process of transcription in bacterial cells:

a. Initiation requires rho protein b. RNA polymerase incorporates methylated c. Both the sigma unit and core enzymes of RNA d. Primase is necessary for initiation

1- d 2- b 3- c

Extra:

1- The correct statement concerning RNA and DNA polymerases is:

a. RNA polymerase uses nucleoside diphosphates b. RNA polymerase requires primers and add c. DNA polymerases can add nucleotides at both d. All RNA and DNA polymerases can add

2- Genetic information flows from:

a. DNA to DNA

b. DNA to RNA

c. RNA to cellular proteins

d. DNA to cellular proteins

3- Eukaryote gene expression is regulated at all the following levels except:

a. mRNA transport

b. Translation

c. Replication

d. Post-transcriptional modifications

e. Transcription

1- d 2- b 3- c

4- Which of the following statements is not correct?

a. Bacteria possess only one type of RNA polymerase

b. Attenuation is a regulatory process used by bacteria to control the initiation of transcription

c. Repressor binds to operator

d. Bacterial genes are polycistronic

5- Which of the following statements about lac operon in E.coli is true?

a. Promoter is the binding site for the lac repressor

b. Operon is only switched on in the absence of lactose in the growth medium

c. β-galactosidase is only produced in large quantities when the lac repressor is bound to the operator

d. Lac operon mRNA is a polycistronic mRNA

6- CAP is:

a. Catabolite gene activator protein b. Catabolite gene repressor protein

c. Anabolite gene activator protein d. Anabolite gene repressor protein 7- In a bacterial operon, which is located downstream of the structural genes?

a. Operator b. Inducer c. Promoter d. Regulatory gene 8- The repressor protein is encoded by: a. Regulatory gene b. Structural gene c. Transfer-DNA d. Ribosomal-RNA 9- Which of the following acts as an inducer in the lac operon? a. Glucose b. Tryptophan c. Lactose d. Galactose 4-b 5-b 6- a 7- d 8- a 9- c 10- Which of the following enzymes are used in the process of transcription?

a. DNA polymerases b. RNA polymerases c. DNA helicase d. DNA topoisomerase 11- Promoter is a:

a. Gene

b. Site on DNA

c. Site on RNA d. Toxin

12- In which of the following levels can gene expression not be exerted?

a. Transitional level b. Transcriptional level c. Reverse transcriptional level d. Processing level

13- What does the structural gene (Y) of a lac operon code for?

a. β-galactosidase b. Transacetylase c. Permease d. Glucagon

14- What does the structural gene (Z) of a lac operon code for?

a. β-galactosidase b. Transacetylase c. Permease d. Glucagon

10- b 11- b 12- c 13- c 14- a

15- Which of the following is responsible for the switching on and off of the lac operon?

a. Lactose b. Ethanol c. Malate d. Fructose

16- What is the regulation of a lac operon by a repressor known as?

a. Neutral regulation b. Positive regulation c. Mixed regulation d. Negative regulation

17- A genomic DNA possesses functioning units, a group of genes under the influence of promoters known as:

a. Genes b. Operons c. Anticodon d. Codon

18-The operator gene of lac operon is 'turned on' when lactose molecules bind to:

a. Operator gene b. Repressor protein c. mRNA d. Promoter site

19- In the absence of glucose, E. coli can import lactose to change into glucose and galactose because CAP binds to the:

a. CAMP b. DNA c. Lac operon d. Operator

20- Regulatory proteins turn transcription off through binding to a site rapidly at the front of the promoter and many times even overlaps the promoter, this site is the:

a. Regulatory site b. Operator site c. Suppressor site

d. Transcriptional control site

15- a 16- b 17- b 18- b 19- a 20- b