1. Which of the following amino acid is acidic?
a) Asparagine
b) Leucine
c) Valine
d) Aspartic acid
Explanation: Aspartic acid is the acidic amino acid among the given options. It contains an extra carboxyl group; hence it has acidic nature. It is negatively charged due do this extra carboxyl group. Aspartic acid and glutamic acid are the only two amino acids that are acidic.
2. What is the three-letter code of Glutamine?
a) Glu
b) Gly
c) Arg
d) Gln
Explanation: The three-letter code for glutamine is Gln. Glutamine is a neutral and polar amino acid. Glu is the three-letter code for glutamine. Gly is the three-letter code for glycine. Arg is the three-letter code for arginine.
3.The three-letter code for threonine is ________
a) Tyr
b) Asn
c) Trp
d) Thr
Explanation: The three-letter code for threonine is Thr. The three-letter codes for tyrosine, asparagine, and tryptophan are Tyr, Asn, and Trp respectively. Threonine is a neutral and polar amino acid.
4.Which among the following is the simplest amino acid?
a) Leucine
b) Alanine
c) Tryptophan
d) Glycine
Explanation: Glycine is the simplest amino acid because it contains hydrogen atom as its side chain. Due to this hydrogen atom, the alpha carbon in glycine is achiral and glycine is optically inactive. Leucine, alanine, and tryptophan contain side-chain groups more complex and bigger than the hydrogen atom.
5. What is the one-letter code for tryptophan?
a) T
b) R
c) F
d) W
Explanation: One-letter code for tryptophan is W. Tryptophan is a neutral and non-polar amino acid. It contains a benzene ring in its structure. T, R, and F are the one-letter codes for threonine, arginine, and phenylalanine respectively.
6. What is the one-letter code for glutamine?
a) G
b) L
c) E
d) Q
Explanation: One-letter code for glutamine is Q. Glutamine is a neutral but polar amino acid. G, L, and E are the one-letter codes for glycine, leucine, and glutamine respectively.
7. What is the one-letter code for tyrosine?
a) T
b) E
c) R
d) Y
Explanation: One-letter code for tyrosine is Y. Tyrosine is a neutral but polar amino acid. It contains a benzene ring and a hydroxyl group in its side chain. T, E, and R are the one-letter codes for threonine, glutamic acid, and arginine respectively.
8. What is the one-letter code for lysine?
a) L
b) Y
c) E
d) K
Explanation: One-letter code for lysine is K. Lysine is a positively charged amino acid and it is basic. L, Y, and E are the one-letter codes for leucine, tyrosine, and glutamic acid respectively.
9. What is the one-letter code for aspartic acid?
a) A
b) S
c) T
d) D
Explanation: One-letter code for aspartic acid is D. Aspartic acid is a negatively charged amino acid and it is acidic. A, S, and T are one-letter codes for alanine, serine, and threonine respectively.
10. Which among the following amino acids is not stable in the water?
a) Aspartic acid
b) Glutamic acid
c) Lysine
d) Leucine
Explanation: Leucine is a neutral and non-polar amino acid, thus it has neither complete nor partial charge to interact with water molecules. Hence, it is not stable in water. Aspartic acid, glutamic acid, and lysine are charged amino acids, hence soluble in water.