Section 5, Chapter 2

Proteins have many functions:

• Proteins provide structural material.

• They are a source of energy.

Organic Molecules: Proteins

• 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

• An amino group (-NH2)

All amino acids consists of:

Proteins: amino acids

• 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 indicatehydrogen bonding

4 Levels of Protein Structure

4 Levels of Protein Structure

4 Levels of Protein Structure

Conformation

• Complex 3 dimensional fold of a protein

• Conformation determines a protein’s function

Protein Structure

Denature

• Treatment that alters the shape of a protein to make it nonfunctional

• Heat, pH changes, radiation, certain chemicals may denature proteins

Nucleic Acids

• Includes DNA and RNA

• Genetic information

• Consists of monomers, called nucleotides

Nucleic acids: overview

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 nitrogenous base

RNASugar = ribose

DNASugar = deoxyribose

H bonds

Antiparallel