MCQ on aminoacid with explanation set 2

MCQ on aminoacid with explanation set 2

Q)Which amino acid, among the 20 standard protein coding amino acids, is most abundantly occurs in proteins?

a) Glycine
b) Methionine
c) Serine
d) Leucine

Answer: option d

Q) Among the 20 standard protein coding amino acids, which was the last discovered amino acid?

a) Leucine
b) Isoleucine
c) Threonine
d) Serine

Answer: option c

Threonine was discovered in 1930 by William Cumming Rose

Q) First discovered amino acid is ____.

a) Asparagine
b) Aspartate
c) Glutamate
d) Glutamine

Answer: option b

Aspartate was discovered from Asparagus racemosus by Plisson in 1827.

Q) Which of the following amino acid is coded by a single codon?

a) Lysine
b) Arginine
c) Tryptophan
d) Phenylalanine

Answer: option c

Methionine is also coded by a single codon

Q) Amino acid acting as a defensive molecule in plants:

a) Canavanine
b) Con-canavalin
c) Proline
d) All of these

Answer: option a

Concanavalin A (ConA) is a lectin isolated from a legume, jack bean (Canavalia ensiformis)

Lectins are protein which specifically binds to carbohydrates.

Q) Majority of enzyme’s active site usually contain one or more _____ residues.

a) Glycine
b) Tryptophan
c) Histidine
d) Arginine

Answer: option c

Histidine has its pI near to physiological pH. The best buffering activity of an amino acid is at a pH which is equal to or near to its pI value (= isoelectric pH). Furthermore, an amino acid at its pI will be in zwitter ionic form and there it can act as both proton donor (acid) and proton acceptor. Since histidine’s pI is near to physiological pH, it can act as a good proton donor and proton acceptor at this pH. This is why the active site of many enzymes contains one or more histidine residues since most of the enzymatic reactions involve exchange of protons and electrons between enzyme and substrates.

Diethylpyrocarbonate (DEPC) which is used in laboratories to inactivate RNase enzyme will inactivate histidine residues in the active site and thereby it deactivate the enzyme.

Q) Which of the following amino acid is having more polarity?

a) Lysine
b) Arginine
c) Histidine
d) Aspartate

Answer: option b

Q) Which of the following amino acid is sweet in taste?

a) Glycine
b) Alanine
c) Glutamic acid
d) None of these

Answer: option a

Q) Amino acid used in the ‘stripping’ of Western blotting experiment is:

a) Glutamic acid
b) Phenyl alanine
c) Alanine
d) Glycine

Answer: option d

‘Stripping’ in western blotting is a procedure of removing protein bounded antibodies from the membrane so that the membrane can be reused to probe with another antibody and hence reduces the sample processing time.

Q)The amino acid commonly used as an ingredient in the buffers of SDS PAGE.

a) Aspartic acid
b) Glutamic acid
c) Glycine
d) Aspartic acid and Lysine together

Answer: option c

Depending up on the pH of buffer, glycine can exist in three different forms (positively charged, no charged and negatively charged)

 

 

 

 

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