AIPMT DISCUSSION QUESTIONS ON GENETIC CODE

Q1. Which of the following is a characteristic of genetic code?

a)      The genetic code is non overlapping

b)      The genetic code is unambiguous

c)       The genetic code is degenerative

d)      All of the above

Explanation:

The correct answer is‘d’. The genetic code is non overlapping means that the successive triplets are read in order.

The genetic code is unambiguous means each codon or triplet specifies a particular amino acid and only one amino acid.

The genetic code is degenerative means each amino acid can be specified by more than one triplet codon.

Q2. Which of the following is a nonsense codon?

a)      UAG

b)      UGA

c)       UAA

d)      All of the above

Explanation:

The correct answer is‘d’. Out of 64 triplet codons, three codons are called nonsense codons because they terminate the process of translation. UAG is amber, UGA is opal and UAA is ochre.

Q3. Which of the following poly bases could not form any amino acid in Nirenberg’s experiment?

a)      Poly U

b)      Poly A

c)       Poly G

d)      Poly C

Explanation:

The correct answer is ‘c’ i.e., Poly G because it formed triple stranded structure and thus no translation occurred.

Q4. Hargobind Khorana chemically synthesized amino acids:

a)      Cysteine/valine 50:50 percent

b)      Proline/Cysteine 50:50 percent

c)       Phenyalanine/ Proline 50:50 percent

d)      All of the above

Explanation:

The correct answer is ‘a’ i.e., cysteine/valine. He used UGUGUGUGU poly nucleotide bases to synthesize the same.

Q5. Which one represents serine?

a)      CUU, CUC, CUA, and CUG

b)      UAU, UAC, UGU, and UGC

c)       UCU, UCC, UCA, and UCG

d)      UGU, UGC, UGA, and UAG

Explanation:

The correct answer is ‘c’. In order to remember which triplet codon codes for which amino acid, one needs to see the codon chart. If we reference Proline which falls on the second row and second column of the codon chart, we can remember the codons. However, a practice is needed for the same.