COMLEX Level 1 Examination
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TABLE OF CONTENTS About the COMLEX Level 1 Examination ..................................................... 1 Preface ........................................................................................................ 3 Chapter One: Biochemistry ......................................................................... 6 Nucleic acids ............................................................................................................... ..... 6 RNA ......................................................................................................................... ....... 14 Nucleic Acid Metabolism ................................................................................................ 17 Carbohydrates ............................................................................................................... . 19 Lipids ...................................................................................................................... ........ 21 Proteins .................................................................................................................... ...... 24 Protein Functions ........................................................................................................... 27 Metabolism of Macronutrients ...................................................................................... 27 Citric Acid Cycle ........................................................................................................... .. 29 Electron Transport Chain .............................................................................................. 31 Gluconeogenesis ............................................................................................................ 32 Fatty Acid Beta Oxidation .............................................................................................. 34 Enzyme Biochemistry .................................................................................................... 34 Metabolic Disorders ....................................................................................................... 3 7 Key Takeaways ............................................................................................................... 42 Quiz ........................................................................................................................ ........ 43
Chapter Two: Microbiology ....................................................................... 46 Cell membranes ............................................................................................................. 46 Transport Mechanisms .................................................................................................. 50
Cellular organelles ......................................................................................................... 55 Pathogens ................................................................................................................... .... 61 Viruses ..................................................................................................................... ....... 61 Pathogenic Bacteria ....................................................................................................... 6 3 Eukaryotic Microbes ...................................................................................................... 65 Parasitic Helminths ....................................................................................................... 6 6 Infectious Diseases ........................................................................................................ 67 Skin Infections and Eye Infections ................................................................................ 67 Respiratory Tract Infections .......................................................................................... 78 Infections of the Urinary Tract ...................................................................................... 86 Infections of the Reproductive Tract ............................................................................. 87 Gastrointestinal Infections ............................................................................................ 90 Circulatory and Lymphatic Infections ........................................................................... 95 Neurological Infections ................................................................................................ 103 Key Takeaways ............................................................................................................. 1 08 Quiz ........................................................................................................................ ...... 109
Chapter Three: Genetics ........................................................................... 112 Mendelian Genetics ...................................................................................................... 112 DNA and Chromosomes ............................................................................................... 118 Gene Expression and Regulation ................................................................................. 123 Mutations ................................................................................................................... ...127
Genetic Diseases .......................................................................................................... 1 29 Key Takeaways ............................................................................................................. 1 36 Quiz ........................................................................................................................ ....... 137
Chapter Four: Anatomy .......................................................................... 140 Tissues ..................................................................................................................... ..... 140 Integumentary System ................................................................................................. 144 Skeletal System ............................................................................................................ 149
Cranium ..................................................................................................................... .. 150 Vertebral Column ......................................................................................................... 15 6 Thoracic Rib Cage ........................................................................................................ 15 9 Appendicular Skeleton ................................................................................................. 159 Upper Limb Skeleton ................................................................................................... 160 Pelvic Girdle ............................................................................................................... .. 165 Lower Limb Bones ....................................................................................................... 166 Muscles ..................................................................................................................... .... 170 Muscles of Facial Expression ........................................................................................172 Neck and Back Muscles ................................................................................................ 173 Abdominal Muscles ...................................................................................................... 174
Thoracic Muscles ......................................................................................................... 17 4 Pelvic Floor Muscles .................................................................................................... 174 Pectoral Girdle Muscles and Arm Muscles ................................................................... 175 Leg Muscles ................................................................................................................. .. 177 Peripheral Nervous System .......................................................................................... 181 Endocrine System ........................................................................................................ 184 Digestive System .......................................................................................................... 1 89 Cardiovascular System ................................................................................................. 196
Blood ....................................................................................................................... .... 200
Respiratory System ...................................................................................................... 201 Genitourinary System .................................................................................................. 204 Reproductive system .................................................................................................... 207 Lymphatic System ........................................................................................................ 212 Key Takeaways ............................................................................................................. 2 13 Quiz ........................................................................................................................ ...... 214
Chapter Five: Physiology .......................................................................... 217 Skin Physiology ............................................................................................................. 217 Skeletal System Physiology .......................................................................................... 218 Muscle Physiology ........................................................................................................ 22 1 Cardiac Muscle ............................................................................................................. 225 Smooth Muscle ............................................................................................................. 2 26 Nervous System Physiology ......................................................................................... 227 Sensory Nervous System .............................................................................................. 235 Motor Nervous System ................................................................................................ 237 Autonomic Nervous System ........................................................................................ 238 Endocrine system Physiology ................................................................................... 241 Digestive System Physiology ....................................................................................... 243 Cardiovascular System Physiology .............................................................................. 246 The Cardiac Cycle ......................................................................................................... 2 48
Respiratory System Physiology ................................................................................... 251 Genitourinary System Physiology ............................................................................... 254 Reproductive System Physiology ................................................................................. 257 Fluid and Electrolyte Balance ...................................................................................... 261
Key Takeaways ............................................................................................................. 2 64 Quiz ........................................................................................................................ ...... 265
Chapter Six: Pathology ............................................................................ 268 Integumentary Pathology ............................................................................................ 268 Skeletal System Pathology ........................................................................................... 278 Muscle Pathology ......................................................................................................... 28 2 Nervous System Pathology .......................................................................................... 284 Endocrine System Pathology ....................................................................................... 292
Digestive system Pathology ........................................................................................ 300 Cardiovascular System Pathology ...............................................................................308 Respiratory System Pathology ...................................................................................... 317 Genitourinary System Pathology ................................................................................. 321 Reproductive System Pathology .................................................................................. 325 Key Takeaways ............................................................................................................. 3 32 Quiz ........................................................................................................................ ...... 333
Chapter Seven: Immunology ................................................................... 336 Innate Immune System ............................................................................................... 336 Cellular Components ................................................................................................... 339 Molecular Immune Components ................................................................................. 343 Inflammation ............................................................................................................... 347 Adaptive Immune System ............................................................................................ 351 Hypersensitivity Diseases ............................................................................................ 353 Diseases of Immunosuppression ................................................................................. 355 Autoimmune Diseases ................................................................................................. 357
Key Takeaways ............................................................................................................. 3 60 Quiz ........................................................................................................................ ...... 361
Chapter Eight: Osteopathic Principles and Practice ................................ 364 Fascial systems ............................................................................................................. 364 Biomechanics ............................................................................................................... 367 Biomechanics of the Low Back .................................................................................... 374 Biomechanics of the Upper Body ................................................................................ 374 Chronic Pain Management .......................................................................................... 375 Stress and Illness ......................................................................................................... 377 Trigger Point Manipulation ......................................................................................... 381 Strain/Counterstrain ................................................................................................... 382 Osteopathic Manipulation ........................................................................................... 383 Key Takeaways ............................................................................................................. 3 87 Quiz ........................................................................................................................ ...... 388
Chapter Nine: Pharmacology .................................................................. 390 Autonomic Nervous System Drugs .............................................................................. 390 Nerve and Neuromuscular Drugs ................................................................................ 392 Seizure Drugs ............................................................................................................... 393 Pain Medications ......................................................................................................... 39 6 Cardiovascular Drugs ................................................................................................... 397 Respiratory Drugs ........................................................................................................ 40 2 GI Drugs .................................................................................................................... ... 404 Genitourinary Drugs .................................................................................................... 406 Hematologic Drugs ...................................................................................................... 406
Endocrine Drugs ......................................................................................................... 408 Psychoactive Drugs ....................................................................................................... 41 1 Anti-infective Drugs ..................................................................................................... 413 Anti-Inflammatory Drugs ............................................................................................ 419 Anti-Allergy Drugs ....................................................................................................... 419 Immunosuppressant Drugs ......................................................................................... 420 Cancer Drugs ................................................................................................................ 421 Key Takeaways ............................................................................................................. 4 24 Quiz ........................................................................................................................ ...... 425
Chapter Ten: Behavioral Science ............................................................. 428 Mood Disorders ........................................................................................................... 42 8 Bipolar Disorder ........................................................................................................... 430 Dissociative Disorders ................................................................................................. 432 Anxiety Disorders ........................................................................................................ 43 4 Personality Disorders ................................................................................................... 437
Psychotic Disorders ..................................................................................................... 441 Somatoform Disorders ................................................................................................. 442 Eating Disorders .......................................................................................................... 4 44 Neurodevelopmental Disorders ................................................................................... 446 Substance Abuse .......................................................................................................... 44 9 Key Takeaways ............................................................................................................. 4 51 Quiz ........................................................................................................................ ...... 452
Chapter Eleven: Health Promotion and Disease Prevention .................... 455 Disease Prevention ....................................................................................................... 45 5
Vaccinations ................................................................................................................ . 457 Screening for Disease ................................................................................................... 458 Ethics in Healthcare ..................................................................................................... 46 2 Nutrition Counseling ................................................................................................... 463 Global Health Problems ............................................................................................... 465 Key Takeaways ............................................................................................................. 4 68 Quiz ........................................................................................................................ ...... 469
Summary ................................................................................................ 472 Course Questions .................................................................................... 475 Answers to Quiz ...................................................................................... 548 Chapter One .............................................................................................................. 54 8 Chapter Two ............................................................................................................. 549 Chapter Three ........................................................................................................... 550 Chapter Four .............................................................................................................. 5 51 Chapter Five .............................................................................................................. 5 53 Chapter Six ............................................................................................................... 5 54 Chapter Seven ........................................................................................................... 555 Chapter Eight ............................................................................................................ 55 6 Chapter Nine ............................................................................................................. 55 8 Chapter Ten .............................................................................................................. 55 9
Chapter Eleven ......................................................................................................... 561 Course Questions ...................................................................................................... 563
ABOUT THE COMLEX LEVEL 1 EXAMINATION The COMLEX Level 1 Examination is the first of three COMLEX tests you will take as part of your osteopathic training. It is a problem-based and symptom-based assessment that assesses what you know about the basic sciences you have learned in your osteopathic college. You need to know these foundational biomedical sciences in order
to later apply them to your clinical practice. There are eleven foundational biomedical sciences that are part of this examination. These include anatomy, behavioral science, biochemistry, genetics, immunology, microbiology, osteopathic principles and practice, pathology, pharmacology, physiology, and health promotion and disease prevention. As you can see, these are basic sciences
necessary to know about as you apply them later to your clinical practice. The COMLEX Level-1 Examination is a computer-based test. It consists of two fourhour blocks of time in which you will answer 400 questions that have five possible answers to answer in a multiple-choice format. Some of these will be clinical questions
but the knowledge itself is based on the basic sciences and not on the clinical sciences. Passing the examination means you have a good foundation in the basic sciences and osteopathic principles prior to entering the supervised patient care setting. There are two distinct dimensions represented seamlessly as part of the test itself. When the two dimensions are applied together, the focus is on osteopathic philosophy on whole person healthcare, interdependence of body systems, underlying structure and function relationships, self-healing and self-regulatory mechanisms, and the osteopathic
approach to patient care, which includes osteopathic manipulative medicine. Dimension 1 consists of seven competency domains. These include the following:
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Osteopathic Principles, Practice, and Manipulative Treatment
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Osteopathic Patient Care and Procedural Skills
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Application of Knowledge for Osteopathic Medical Practice
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Practice-based Learning and Improvement in Osteopathic Medical Practice
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Interpersonal and Communication Skills in the Practice of Osteopathic Medicine
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Professionalism in the Practice of Osteopathic Medicine
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Systems-based Practice in Osteopathic Medicine
Dimension 2 involves ten areas of clinical presentations, including these:
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Community Health and Patient Presentations Related to Wellness
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Human Development, Reproduction, and Sexuality
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Endocrine System and Metabolism
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Nervous System and Mental Health
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Musculoskeletal Health
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Genitourinary/Renal System and Breasts
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Gastrointestinal System and Nutritional Health
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Circulatory and Hematologic Systems
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Respiratory System
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Integumentary System
As mentioned, you will answer 400 questions in a multiple-choice format. Four hours for each half of the test are allowed for you to complete these questions, with three optional breaks. Two breaks will be 10 minutes in duration, while one break involves a 40-minute lunch period. You will receive a raw score that will be converted into a standard score for which there will be a pass-fail determination. Your percentile score will not be given but you can convert your standard score into a percentile determination if you choose to do so. There will be a graphical representation of your performance that summarizes your strengths and weaknesses as they apply to the
examination blueprint.
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PREFACE The purpose of this audio course is to help you prepare for the COMLEX Level 1 Examination, which will be one of several examinations required for graduation from an osteopathic college and for entering an osteopathic residence program. When you take the actual exam, it will be taken on a single day in two four-hour blocks of time. The total number of test questions in your examination will be 400 in total. The Level 1 examination relies on your understanding of the basic sciences you have studied in osteopathic school. The different areas of study include biochemistry, microbiology, genetics, immunology, anatomy, physiology, pathology, osteopathic principles and practice, behavioral sciences, and health promotion/disease prevention. There will be questions after each chapter and a final set of questions that will help you prepare for
this important examination. The focus of chapter one in the course is biochemistry and biochemical principles. This is basically the study of organic molecules found in human systems as well as how these are synthesized and broken down. The major macromolecules are nucleic acids, carbohydrates, lipids, and proteins. There are various metabolic processes involved in these molecules. Much of biochemistry involves enzyme biochemistry so this is also
covered as part of this chapter. Chapter two covers many of the important issues in microbiology. Eukaryotic cellular structures, such as the cell membrane, transport systems, and intracellular organelles are covered, as are the different pathogens that can affect the human body. Finally, we discuss the different infectious diseases an osteopath might encounter as part of clinical practice. These include viral, bacterial, protozoal, and parasitic diseases of the different
organ systems. Chapter three in the course involves the subject of human genetics. We will first talk about Mendelian genetics, which is the basis of how genes are passed from a parent organism to subsequent generations. DNA and chromosomes are also covered, as these things represent the basis of genetics in eukaryotes. How genes are regulated in the
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eukaryotic organism is an important part of the study of genetics. As a healthcare provider, you will need to know about some of the more common genetic diseases, so
these are discussed as part of this chapter. The purpose of chapter four is to uncover the anatomy of the human body. There are different types of tissues that together create the organs of the body, which will be discussed. Also covered in this chapter are the different organ systems making up the human body. You will need to understand the different aspects of each of these systems and how these systems work together to allow the human body to function, so these are
covered in this course. The purpose of chapter five in the course is to uncover the different physiological processes of the human body. Out of an organ system’s form comes its function, which is important to understanding how the different body systems work in isolation and with one another. Each of the different body systems and their physiological functions
is covered in this chapter. Chapter six talks about the pathology of different body systems. As part of this chapter, we will talk about the diseases of the skin, muscles, bones, digestive system, cardiovascular system, endocrine and metabolic systems, respiratory system,
genitourinary system, and reproductive systems of the male and female. Chapter seven in the course focuses on the important topic of immunology in human systems. There are two arms of the immune system, which are the innate and adaptive immune system. There are cellular and molecular components of both of these systems, which are discussed in the chapter. Diseases related to the immune system are also covered, including immunosuppression, hypersensitivity disorders, and autoimmune
diseases. Chapter eight will introduce you to the principles and practice of osteopathic medicine. Part of this is an understanding of the fascial systems of the body as well as the ways that osteopaths manage acute and chronic pain. The interplay between stress and illness is discussed in the chapter as well as osteopathic manipulation techniques,
such as trigger point manipulation and other osteopathic manipulation techniques.
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Chapter nine in the course talks about pharmacology and the vast numbers of drugs used to treat different medical and psychiatric disorders. This involves a knowledge of the biochemical basis of disease states along with how modern pharmacologic drugs work with the biochemistry of the body in order to affect resolution of symptoms or the cure of a variety of illnesses. Drugs involved in the treatment of all body system
disorders are discussed in this chapter. Because of the strong interplay between physical diseases and psychological disorders,
chapter ten is devoted to the study of behavioral science and the different psychiatric disorders that a healthcare practitioner might encounter as part of everyday practice. These include common disorders, such as mood disorders, and those that are not as common, such as neurodevelopmental disorders and psychoses, which need to be
understood in the conquest of studying the whole person in osteopathic practices. Because primary care medicine places a strong focus on health promotion and disease
prevention, these are the main topics of chapter eleven in the course. Disease prevention happens at many different levels to address diseases and their outcomes at several different stages of disease processes. Vaccinations are a big part of disease prevention so this is a topic in this chapter. Screening for the different health problems starts in infancy and continues throughout live, so this is covered in the chapter. Nutritional recommendations are also a big part of primary care practices. Medical
ethics and the major global health concerns today are also discussed in this chapter.
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CHAPTER ONE: BIOCHEMISTRY The focus of this chapter is biochemistry and biochemical principles. This is basically the study of organic molecules found in human systems as well as how these are synthesized and broken down. The major macromolecules are nucleic acids, carbohydrates, lipids, and proteins. There are various metabolic processes involved in these molecules. Much of biochemistry involves enzyme biochemistry so this is also
covered as part of this chapter.
NUCLEIC ACIDS Nucleic acids are one type of macromolecule in cellular structures. They make up the genetic code, transfer genetic information from one organism to its offspring, and
participate in protein synthesis through complex biochemical mechanisms. Nucleotides are the building blocks of nucleic acids, which are considered polynucleotides or long-chain molecules consisting of stretches of nucleotides. A nucleotide consists of a nitrogenous aromatic base that has been attached to a fivecarbon pentose sugar, which is attached to a phosphate group. Figure 1 shows what a
nucleotide looks like:
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Figure 1.
There are five possible nitrogenous bases. These are adenine, thymine, guanine, cytosine, and uracil. They are labeled in nucleic acid structures using the initial representing the first letter of their name. Adenine and guanine are purine bases, while cytosine, thymine, and uracil are pyrimidine bases. The two important nucleic acids are DNA and RNA. DNA contains A, G, C, and T, while RNA does not have thymine but has A, G, C, and U. Figure 2 shows the biochemical structure of the different nitrogenous
bases:
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Figure 2.
The pentose sugar in DNA and RNA is different. DNA contains deoxyribose as its pentose sugar, while RNA contains ribose as its pentose sugar. If the nitrogenous base plus the pentose sugar are connected, these are called nucleosides. Once the nucleoside has a phosphate group on it, it is called a nucleotide. The connections between nucleotides occurs by linking the 3-prime hydroxyl group of one pentose sugar to the
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five-prime sugar of the adjacent pentose sugar through phosphodiester bonds. Figure 3 shows the structure of a nucleic acid:
Figure 3.
Nucleic acids are made from precursors in the cell. The pentose phosphate pathway takes glucose and turns it into a pentose sugar, which is a five-carbon sugar. The purines and pyrimidines are synthesized while attached to a phosphate group, located on the 5prime carbon atom on the pentose sugar. In DNA, the 2-prime hydroxyl group on ribose
is replaced with a hydrogen ion to make a hydrogen side group and deoxyribose instead. Once a deoxyribonucleoside triphosphate is made, the linkage to make DNA happens because the triphosphate bond is a high energy bond that can drive the reaction, getting
rid of two phosphates so that only the nucleotide is left to make the nucleic acid.
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There is a great deal of recycling that goes on inside the cell. RNA is always being synthesized and broken down. Rather than waste these nucleotides, the purines and
pyrimidines are salvaged and reused to make additional genetic material. DNA itself is a polymer of A, C, G, and T. It forms a ladder-like structure through the alternation of phosphates and deoxyribose sugars, attached through phosphodiesterase linkages between the 5-prime hydroxyl group on one pentose sugar and the 3-prime hydroxyl group on the adjacent pentose sugar. Figure 4 shows what the two major
pentose sugars are in DNA and RNA:
Figure 4.
The structure of DNA is a twisted double helix, as identified by several researchers, including Watson and Crick, in 1953. This double helix comes from the parallelantiparallel strands of two DNA polynucleotides that come together from hydrogen bonding between adenine to thymine and from cytosine to guanine. Figure 5 is the
double-helical structure of DNA.
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Figure 5.
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The helix will make a complete turn about every 10 base pairs. There is a wider major groove to the molecule and a narrow minor groove to the molecule. The major groove is wide enough to allow proteins to interact with the DNA molecule, which help to regulate
things like DNA super-folding, replication of DNA, and translation of DNA to RNA. DNA that is naturally occurring in the cell may be linear or circular. DNA Is linear in prokaryotic cells, such as archaea and bacteria, as well as in mitochondria and chloroplasts of eukaryotic cells. Plasmids, which are pieces of DNA passed from one cell to another, are also circular. Eukaryotes, such as fungi, plants, and animals, have linear DNA arranged in a linear fashion in the form of chromosomes. Each type of organism has its own number of chromosomes, located in the cell nucleus. Humans have 23 pairs of chromosomes, of which 22 pairs are homologous or roughly the same structure, while one pair consists of the sex chromosomes, labeled X and Y, that do not share the same
genes on them. DNA does not exist as naked DNA in the cell but is tightly wound due to the presence of proteins that make chromatin. There are histone proteins in eukaryotic cells that wrap around the DNA molecule in order to condense it. Each histone-DNA segment is called a nucleosome, which looks like a bead on a string. These need to be disassembled to some degree before the DNA can be replicated or transcribed into RNA. Figure 6 shows a
nucleosome:
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Figure 6.
As mentioned, the two strands of DNA are held together by the hydrogen bonds between base pairs that are complementary to one another. If these strands are heated, they will separate in a process that is called denaturation. They can come together again if they
are cooled. These processes are used by biochemists to identify the structure of DNA. DNA can undergo different modifications after it has been assembled. There are, for example, DNA methyltransferases that methylate the DNA molecule. Ionizing
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radiation, carcinogens, and oxidation can all modify DNA. Nucleases can cleave or
degrade the DNA molecule. Methylation happens three ways in the DNA molecule. Cytosine can be methylated in two ways to make two types of methylcytosine molecules, while adenine can be methylated in one way. Sometimes, methylation can occur not
because of enzymes but because of exposure to carcinogens. Natural methylation is important to bacterial and archaeal immune systems by protecting DNA from being fragmented by restriction endonucleases. Methylation also prevents mistakes in the process of DNA replication. Methylation will inactivate the gene associated with the piece of DNA and will control differentiation in embryos. Five-
methylcytosine can be mutagenic because it can lead to a GC pair becoming an AT pair. Nucleases will break the phosphodiesterase bond in DNA. There are endonucleases that make cleavage points in the middle of the chain, while exonucleases act on the end of the chain. Restriction endonucleases are used to make recombinant DNA pieces in
recombinant DNA technology. Circular DNA has the ability to supercoil. This happens when one strand is broken and winds many times around its complementary strand until it becomes a tight ball taking up very little space. This can be reversed. There are topoisomerases and gyrases, which are enzymes that unwind and relax the supercoiled DNA. Supercoiling happens to some degree in eukaryotic linear chromosomes as well. The goal is to compact the DNA so it
fits within the nucleus. DNA can now be sequenced. The sequence is based on the different chemical reactivities of the bases on the DNA strand. DNA fragments are separated through gel electrophoresis, which separates the bases. Fluorescent labeling is done to determine
which base pair is located on which part of the DNA molecule.
RNA RNA is also a nucleic acid type but has A, C, G, and U as its bases. There are ribose sugars connected to other ribose sugars by phosphodiesterase linkages between the ribose hydroxyl groups. RNA is largely single-stranded but this gives it the ability to be synthesized correctly by binding to a strand of DNA and creating a matching RNA
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COURSE QUESTIONS 1.
Answer: c. You should be aware of the fact that adenine hydrogen bonds with thymine and guanine hydrogen bonds with cytosine in order to create the
double helix in the DNA molecule.
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Answer: a. Each of these contains a circular piece of DNA, except for
eukaryotic cells, which 12.
Answer: b. There are 22 pairs of homologous chromosomes in the human cell, along with one pair of non-homologous chromosomes, which is the XY
chromosome pair set. 13.
Answer: c. The nucleosome is the protein-DNA structure of DNA that consists of DNA wrapped around a histone protein. This looks like beads on a string
along the chromosome of the DNA molecule.
14.
Answer: e. Nucleases break DNA strands by breaking the phosphodiester
bond between two pentose sugars. 15.
Answer: c. Spliceosomes make the final form of RNA by splicing out introns and keeping exons that get transcribed from the modified and mature RNA
molecule. 16.
Answer: e. DNA helicase will separate the DNA strands in order to participate
in the DNA replication process. 17.
Answer: b. Transcription is the process where there is a DNA template that
serves to make RNA. 18.
Answer: a. Each of these is an active participant in the making of protein in the translation process; however, small nuclear RNA does not play an active
role in this. 19.
Answer: c. Sucrose is made from a combination of glucose and fructose,
connected by a glycosidic bond to one another.
20.
Answer: e. Bile acids are made in the liver and help to emulsify fats so that
they can be digested and absorbed in the gastrointestinal tract.
21.
Answer: c. Plasmalogens are important in platelet activation because platelet activating factor is important in anaphylaxis and in serotonin release from the
platelets when they become activated. 563
22.
Answer: e. The myelin sheath in humans is mainly made from sphingolipids,
which are also made into other types of lipids, such as cerebrosides.
23.
Answer: a. Only glycine is not chiral because its formula is so simple and has
only hydrogen as its side chain. 24.
Answer: b. Each of these actually contributes to the primary structure of a peptide or protein; however, it is hydrogen bonding that helps to form the
secondary structure of the molecule.
25.
Answer: d. The main thing that determines the tertiary structure of a peptide chain is the hydrophobic or hydrophilic nature of the side chains of the amino
acids. Disulfide bonds will play a minor role in this structural conformation.
26.
Answer: c. Hemoglobin is an iron-containing metalloprotein. If there is a lack of iron for any reason, hemoglobin cannot be made and there will be iron-
deficiency anemia. 27.
Answer: d. ATP and NADH are the two energy molecules made during the glycolysis pathway. Molecules of ATP are consumed but then are replaced
and added to as part of the process. 28.
Answer: c. Anything that has energy or contains one of the end-products of pyruvate dehydrogenase will inhibit pyruvate dehydrogenase. Low-energy molecules, such as AMP, will stimulate pyruvate dehydrogenase, which makes
acetyl CoA plus NADH. 29.
Answer: b. Anytime a kinase acts on a substrate, its activity is to
phosphorylate the substrate. There are numerous kinases found in cells.
30.
Answer: e. The electron transport chain is a series of subunits imbedded in the inner mitochondrial membrane and participates in the passage of
electrons from one molecule to another in a series of redox reactions.
31.
Answer: d. ATP synthase is driven by the passage of hydrogen ions through
the membrane down its electrochemical gradient.
32.
Answer: b. Molecules of acetyl CoA get made as fatty acids get broken down to
make energy through beta-oxidation.
33.
Answer: c. The enzyme will lower the energy level of the reaction intermediates so it will effectively lower the activation energy but it will not
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