Structural Biology Mid - I, September - 2014

1.The width of the DNA double helix is
  • 20A0
  • 3.4A0
  • 24A0
  • 30A0
Answer: B
2.Chaperon proteins function by
  • Providing a protective environment which proteins can fold properly
  • Degrading proteins that have folded improperly
  • Rescuing proteins that folded incorrectly and allowing them to refold into proper configuration
  • All of the above
Answer: C
3.An average protein will not be denatured by
  • SDS
  • heating to 900C
  • Iodoacetic acid
  • Urea
Answer: C
4.Vitamin K is required for
  • Change of prothrombin to thrombin
  • Synthesis of prothrombin
  • Change of fibrinogen to fibrin
  • Formation of thromboplastin
Answer: B
5.The chirality of an amino acid results from the fact that it’s carbon is
  • Has no net charge
  • is a carboxylic acid
  • is bonded for four different chemical groups
  • is symmetric
Answer: C
6.Two amino acids of the standard 20 contain sulphur atoms they are
  • Alanine is a simple methyl group
  • Cysteine & cystine
  • Lysine contains only hydrogen
  • Glysine is unbranched
Answer: B
7.A Peptide bond is
  • Has a partial double bond character
  • is ionized at physiological pH
  • is stable to heating in strong acids
  • Occurs most commonly in the cis configuration
Answer: A
8.At neutral pH a mixture of amino acids in solution would be predominantly
  • Hydrophobic
  • negative and monovalent
  • Hydrophobic
  • Dipolar
Answer: D
9.The interactions of ligands with proteins
  • Usually results in the inactivation of the proteins
  • are relatively rare in biological systems
  • Are usually irreversible
  • are usually transient
Answer: D
10.All of the amino acids that are found in proteins except for proline a(n)
  • Amino group
  • Carboxyl group
  • Carbonyl group
  • Alcohol group
Answer: A
11.In prokaryotes the first amino acid in polypeptide chain is_______________________
Answer: N-FORMYL METHIONINE
12.Polysomes are____________________
Answer: m RNA MOLECULE TO WHICH MANY RIBOSOME ARE ATTACHED SIMULTANEOUSLY
13.Tetra cyclins blocks protein synthesis by______________________
Answer: INHIBITING THE BINDING OF AMINO ACYL t RNA TO RIBOSOME
14.______________________ forces are the most favorable for protein folding.
Answer: HYDROPHOBIC INTERACTIONS
15.Attractive Vander Waals forces occur between, nearby any______________________
Answer: ATOMS
16.For the unfolding reaction of Protein G, ΔH° =210.6 kJ/mol, this means that__________________
Answer: FOLDING IS FAVOURED ENTHALPICALLY
17.Unpaired H-bond donors and acceptors are found in the hydrophobic core of a protein____________
Answer: RARELY
18.If the egg white protein, ovalbumin, is denatured in a hard-boiled egg, then which of the following is least affected___________________
Answer: THE PRIMARY STRUCTURE OF OVAALBUMIN
19.Buried hydrophobic side chains in a globular protein fit into a hole formed by the side chains of _________________________
Answer: 5-7 OTHER AMINO ACIDS
20.__________________Forces are the most unfavorable for protein folding.
Answer: CONFORMATIONAL ENTROPY