Biochemistry Protein Structure and Function 3

Question 1

Collagen's unique triple-helix structure is stabilized primarily by which amino acid's repeated occurrence?

Accepted Answer

Both B and C

Answer

Alanine

Answer

Glycine

Answer

Proline and hydroxyproline

Question 2

Vitamin C (ascorbate) is required for collagen synthesis because it is needed for:

Accepted Answer

Hydroxylation of proline and lysine residues

Answer

Glycosylation of collagen fibers

Answer

Cross-linking of collagen fibrils

Answer

Secretion of procollagen from fibroblasts

Question 3

Which class of proteins contains immunoglobulin-fold domains and is central to adaptive immunity?

Accepted Answer

Antibodies (immunoglobulins)

Answer

Fibrous proteins

Answer

G-protein coupled receptors

Answer

Nuclear receptors

Question 4

A signal peptide on a newly synthesized protein directs it to which cellular location for processing?

Accepted Answer

Rough endoplasmic reticulum

Answer

Nucleus

Answer

Mitochondria

Answer

Cytosol

Question 5

Ubiquitin-mediated proteasomal degradation requires that ubiquitin chains be attached to which amino acid residue of the target protein?

Accepted Answer

Lysine

Answer

Serine

Answer

Cysteine

Answer

Aspartate

Question 6

The Bohr effect refers to which property of hemoglobin?

Accepted Answer

Decreased O₂ affinity at lower pH and higher CO₂

Answer

Increased O₂ affinity at low temperature

Answer

Increased O₂ affinity when 2,3-BPG binds

Answer

Decreased O₂ affinity at high altitude