Biochemistry: Macromolecules Part 2 AP Biology Biochemistry: Macromolecules Part 2

Proteins

LE 5-UN78 a carbon Amino group Carboxyl group

Fig: 5.17a

Fig: 5.17b

Dehydration and Hydrolysis Reactions again Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Longer polymer Dehydration reaction in the synthesis of a polymer Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer

Peptide Bonding

Primary (1’) sequence

Primary Structure is IMPORTANT

Sickle Cell and Oxygen transport Normal hemoglobin Sickle-cell hemoglobin Primary structure Val His Leu Thr Pro Glu Glu Primary structure Val His Leu Thr Pro Val Glu 1 2 3 4 5 6 7 1 2 3 4 5 6 7 Exposed hydrophobic region Secondary and tertiary structures Secondary and tertiary structures b subunit b subunit a a   Quaternary structure Normal hemoglobin (top view) Quaternary structure Sickle-cell hemoglobin a   a Function Molecules do not associate with one another; each carries oxygen. Function Molecules interact with one another to crystallize into a fiber; capacity to carry oxygen is greatly reduced.

2’ structure

3’ Structure

4’ Structure

Protein’s Natural Form

Denaturation of a protein

Chaperonin

Nitrogen Cycle and Proteins N2 in atmosphere Assimilation Denitrifying bacteria NO3– Nitrogen-fixing bacteria in root nodules of legumes Decomposers Nitrifying bacteria Ammonification Nitrification NH3 NH4+ NO2– Nitrogen-fixing soil bacteria Nitrifying bacteria