AMINO ACIDS

Question 1

are the most abundant and functionally diverse molecules in living systems.

Answer 1

Proteins

Question 2

direct and regulate metabolism in the body, whereas contractile proteins in muscle permit movement.

Answer 2

Enzymes and polypeptide hormones:

Question 3

have a carboxyl group, a primary amino group (except for proline, which has a secondary amino group), and a distinctive side chain (“R group”) bonded to the α-carbon atom

Answer 3

Amino Acids

Question 4

is the result of the hydrophobicity of the nonpolar R groups, which act much like droplets of oil that coalesce in an aqueous environment.

Answer 4

hydrophobic effect

Question 5

its side chain and α-amino N form a rigid, five-membered ring structure.
has a secondary (rather than a primary) amino group.
It is frequently referred to as an “imino acid.”

Answer 5

Proline

Question 6

Two disulfide-linked cysteines are referred to as

Answer 6

cystine

Question 7

is the only amino acid with a side chain that can ionize within the physiologic pH range.

Answer 7

Histidine

Question 8

is a solution that resists change in pH following the addition of an acid or base.

Answer 8

Buffers

Question 9

is the linear sequence of amino acids in a protein. It is determined by the DNA sequence of the gene that codes for the protein.

Answer 9

PRIMARY STRUCTURE OF PROTEINS

Question 10

is the formation of regular arrangements of amino acids that are located near each other in the linear sequence.

Answer 10

SECONDARY STRUCTURE OF PROTEINS

Question 11

-the most common of the helices
spiral structure, tightly packed, coiled polypeptide backbone core, with the side chains of the component amino acids

Answer 11

a-Helix

Question 12

–surfaces of β-sheets appear “pleated”
β-strands are often visualized as broad arrows

Answer 12

β-Sheet

Question 13

reverse the direction of a polypeptide chain, helping it form a compact, globular shape.

Answer 13

β-Bends (reverse turns, β-turns)

Question 14

• refers both to the folding of domains (the basic units of structure and function), and to the final arrangement of domains in the polypeptide.

Answer 14

TERTIARY STRUCTURE OF GLOBULAR PROTEINS

Question 15

involves non-random, ordered pathways

Answer 15

Protein folding

Question 16

results in the unfolding and disorganization of a protein’s secondary and tertiary structures without the hydrolysis of peptide bonds.

Answer 16

Denaturation of proteins

Question 17

is the three-dimensional arrangement of multiple protein subunits.

Answer 17

QUATERNARY STRUCTURE OF PROTEINS

Question 18

accumulation of these insoluble, spontaneously aggregating proteins, called amyloids (Parkinson, Huntington, and Alzheimer disease).

Answer 18

Amyloid disease