Protein Structure - Exam Questions

Question 1

What is the function of transferrin?

Answer 1

Transport

Question 2

Peptide bonds:

a. have a partial positive charge on the O atom
b. are able to rotate around the C-N bond
c. have some features of double bonds
d. cannot form H-bonds with other peptide bonds
e. have a cis arrangement of the O and H branches

Answer 2

c. Peptide bonds have some features of a double bond.

Question 3

Glycosylation can link a carbohydrate to the following residue via the specified linkage:

Answer 3

Threonine (O-linked)

Question 4

Methylation may occur via the NH2 group of:

a. lysine
b. asparagine
c. glutamine
d. glutamate
e. histidine

Answer 4

a.Lysine

Question 5

Glutathione is a:

a. dipeptide
b. amino acid
c. tripeptide
d. short polypeptide
e. large protein

Answer 5

c. Glutathione is a tripeptide of glutamate, glycine and cysteine.

Question 6

The alpha helix:

a. may be formed between residues of different polypeptide chains
b. is left handed
c. contains 6.3 residues per turn
d. forms H bonds between O and H atoms from peptide bonds
e. has the R groups on the inside

Answer 6

d. the alpha helix forms H bonds between O and H atoms from different peptide bonds.

Question 7

Beta sheets:

a. are always parallel
b. are always antiparallel
c. always have side chains alternating above and below the plane of the sheet
d. always have side chains on the same side of the sheet.
e. do not occur in globular proteins.

Answer 7

c. Beta sheets always have side chains alternating above and below the plane of the sheet.

Question 8

A collagen strand:

a. is a left handed helix
b. is a double helix
c. has four residues per turn
d. is coiled around three other collagen strands to form a collagen fibril
e. contains only glycine, proline and hydroxyproline residues

Answer 8

a. A collagen strands is a left handed helix.

Question 9

A high proportion of beta-beta sheet is likely to be found in what?

Answer 9

Fibroin

Question 10

Name two super secondary domains?

Answer 10

Beta-sandwich

Beta barrel

Question 11

What is the hydrogen bond length?

Answer 11

2.8A

Question 12

What can proteins be denatured by?

Answer 12

High temperatures, low pH

Question 13

What are amyloid proteins?

Answer 13

Stable proteins that aggregate to form plaques

Question 14

Pathogenic prions:

a. have a different amino acid sequence to normal prions
b. are produced by the virus that causes CJD
c. polymerise to form fibrils
d. are re-converted to a normla folding by contact with normal prions
e. are more susceptible to proteolysis than normal prions

Answer 14

c. Pathogenic prions polymerise to form fibrils

Question 15

Where is hydroxyproline found?

Answer 15

In collagen