Organic Molecules: Proteins Proteins have many functions:
• Proteins provide structural material. • They are a source of energy. • Some act as chemical messengers (hormones, neurotransmitters). • Many proteins are receptors. • Most enzymes are proteins.
Proteins: enzymes Enzymes catalyze reactions (increases rate), but are not consumed by the reaction (reusable).
Synthesis reaction involving an enzyme
Proteins: amino acids
All amino acids consists of:
• An amino group (-NH2) • A Carboxyl Group (-COOH) • A single Carbon atom • An “R” group (R = rest of the molecule) • 1 of 20 possible “R” groups = determines amino acid
Peptide bond (red) joins two amino acids.
4 Levels of Protein Structure A protein’s shape, or conformation, determines its function. Therefore, it’s important to understand a protein’s shape at 4 levels.
4 Levels of Protein Structure
Red dots indicate hydrogen bonding
4 Levels of Protein Structure
4 Levels of Protein Structure
4 Levels of Protein Structure
Protein Structure Conformation • Complex 3 dimensional fold of a protein • Conformation determines a protein’s function
Denature • Treatment that alters the shape of a protein to make it nonfunctional • Heat, pH changes, radiation, certain chemicals may denature proteins
Nucleic acids: overview
Nucleic Acids • Includes DNA and RNA • Genetic information • Consists of monomers, called nucleotides
RNA • • • •
Contains the sugar ribose (ribonucleic acid) RNA is a single-stranded nucleic acid. Transcribes DNA for protein synthesis RNA also may act as an enzyme
DNA • DNA contains a sugar, called deoxyribose (deoxyribonucleic acid) • Double-stranded helix • Encodes genetic information for protein synthesis.
Nucleotides • Monomers of Nucleic Acids
3 Components of Nucleotides • 5 Carbon Sugar (S) • Nitrogenous Base (B) • Phosphate Group (P)
sugar phosphate
RNA Sugar = ribose DNA Sugar = deoxyribose
nitrogenous base
H bonds
Antiparallel