Question

In the genetic code dictionary, how many codons are used to code for all the $20$ essential amino acids?

• A. 61
• B. 60
• C. 20
• D. 64

Answer 1

Answer: (A)

Out of $64$ codons three (UAA, UAG, UGA) are chain terminating codons- the translating mechanism is not able to read these codons
(a) $61$ codons are used to code all the $20$ essential amino acids.
(b) Out of $64,3$ codons, UAA, UAG, UGA does not code any amino acid molecule.