Amino Acids and Their Functions

These flashcards cover key concepts about amino acids, their functions, structures, and biological significance.

What are amino acids (AAs) primarily responsible for in biology?

Building blocks of proteins and catalyzing reactions as enzymes.

What are the two types of storage for amino acids in living organisms?

Amino acids cannot be stored; those not used are converted into metabolic intermediates or fat.

How do amino acids influence protein structure?

Amino acids dictate the folding and stability of proteins.

What is the difference between an amino acid and an amino acid residue?

An amino acid is free with both a free α amino group and carboxyl group; a residue is part of a peptide chain.

In solution, what form do amino acids typically take at neutral pH?

They exist predominantly as zwitterions.

What is the isoelectric point (pI) of an amino acid?

The pH at which the concentration of positively and negatively charged species is equal.

What designates an amino acid as 'α' amino acid?

It refers to the carbon atom being the central carbon, bonded to an α-carboxyl group and an α-amino group.

What is the significance of stereochemistry in amino acids?

Most amino acids in proteins are L-isomers, indicating their specific spatial arrangement.

How many categories are amino acid side chains classified into?

Seven categories: aliphatic, aromatic, hydroxyl-containing, sulfur-containing, basic, acidic, and amide side chains.

What is the relationship between the hydrophobicity of amino acids and their side chains?

Hydrophobic side chains have unfavorable free energy of transfer to a hydrophilic solvent.

What kind of post-translational modifications can affect proteins?

Chemical modifications like hydroxylation, carboxylation, phosphorylation, and disulfide bond formation.

What role does Vitamin C play in post-translational modifications?

It is required for the hydroxylation of proline or lysine in collagen synthesis.

What happens during phosphorylation?

Specific amino acids like serine, threonine, or tyrosine receive phosphate groups from kinases.

What type of bond is formed through the oxidation of cysteine residues?

Disulfide bonds, which create covalent crosslinks.