Question

Which of the following statements is correct regarding the number of codons and their degeneracy?

• A. There are 20 codons, and all of them exhibit degeneracy.
• B. There are 64 codons, and none of them exhibit degeneracy.
• C. There are 64 codons, and some of them exhibit degeneracy.
• D. There are 20 codons, and none of them exhibit degeneracy.

Hint:

Degeneracy of the genetic code ensures redundancy and minimizes the effects of mutations. Although there are 64 codons, only 20 amino acids are encoded, leading to multiple codons for certain amino acids.

Answer 1

The Correct Option is C

Step 1: Codon and Degeneracy Fundamentals.
The genetic code comprises codons, which are three-nucleotide sequences in mRNA. There are 64 possible codons formed by the permutation of four bases (A, U, G, C) in groups of three. Of these: 61 codons specify amino acids. 3 codons signal termination of protein synthesis (UAA, UAG, UGA).Degeneracy signifies that multiple codons can specify the same amino acid. For instance: Leucine is encoded by six distinct codons (CUU, CUC, CUA, CUG, UUA, UUG). Methionine is encoded by a single codon (AUG), indicating no degeneracy.Step 2: Option Evaluation.
Option (A): Incorrect. 64 codons exist, not 20, and not all are degenerate. Option (B): Incorrect. Degeneracy is present in some codons; it is false that none are degenerate. Option (C): Correct. There are 64 codons, and many display degeneracy by encoding the same amino acid. Option (D): Incorrect. 64 codons exist, not 20, and degeneracy is a feature.Step 3: Conclusion.
The accurate statement asserts that there are 64 codons, and some exhibit degeneracy.\[\therefore \text{The correct answer is: There are 64 codons, and some of them exhibit degeneracy.}\]