MCQ on protein with explanation set 2

MCQ on protein with explanation set 2

Q) In species X a critical polypeptide has following aminoacid sequence:

(Met – ala – cys – cys – phe – try – phe – pro)

The aminoacid sequence of five other species determined. Which of these species is probably LEAST related to species X?

A) Met – ala – cys – cys – phe – try – Ile – pro.

B) Met – ala – ser – cys – phe – try – phe – pro.

C) Met – ala – cys – cys – phe – arg – phe – pro.

D) Met – ala – ser – cys – arg – try – phe – pro.

Answer: D

Explanation: In the D option 2 aminoacids in the sequence are different. All others single aminoacid difference.

Q) Which of the following does not affect the stability of a α-helix?
a) Electrostatic repulsion
b) Bulkiness
c) Interaction between R groups spaced three residues apart
d) Occurrence of alanine and glycine residues

Answer: option d

Q) Which of the following is false statement?
a) α-Keratin is α helical
b) Collagen is α helical
c) Hemoglobin has a quaternary structure
d) α-Keratin is β pleated structure

Answer: option d
Explanation: Fibrous structural protein, α-Keratin is α helical.

Q) During the formation of the peptide bond which of the following takes place?
a) Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
b) Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
c) Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
d) Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid

Answer: option a
Explanation: The α-amino group of one amino acid acts as a nucleophile to displace the hydroxyl group of another amino acid forming a peptide bond.

Q) Which of the following information is responsible to specify the three-dimensional shape of a protein?
a) The protein’s peptide bond
b) The protein’s amino acid sequence
c) The protein’s interaction with other polypeptides
d) The protein’s interaction with molecular chaperons

Answer: option b

Q) Which of the following is an inhibitor of protein synthesis?

a) Pencillin

b) Chloramphenicol

c) Actinomycin D

d) Bacitracin

Answer: Option B

Q) Which of the following is useful for identifying amino terminal residue of proteins?

a) Cyanogen bromide

b) Fluorodinitrobenzene

c) Performic acid

d) Dansyl chloride

Answer: Option d

Q) Which one of the following amino acid residues is specifically recognised by chymotrypsin during peptide bond cleavage?
a) Phe
b) Leu
c) Val
d) Asp

Answer: Option A

Q) In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by:
a) Fe2+
b) heme binding.
c) oxygen binding.
d) subunit association.

Answer: option C

Q) Myoglobin and the subunits of hemoglobin have:

a) no obvious structural relationship.
b) very different primary and tertiary structures.
c) very similar primary and tertiary structures.
d) very similar tertiary structures, but different primary structures.

Answer: option D

 

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