The genetic code is said to be “degenerate” because:
different organisms use different codons to encode the same amino acid.
some codons specify more than one amino acid.
both template and coding strands code for the same molecule.
there are more amino acids than codons.
there are more codons than amino acids.
The correct answer and explanation is :
The correct answer is: there are more codons than amino acids.
Explanation:
The genetic code is described as “degenerate” because of the redundancy inherent in the system of codons. The term “degeneracy” in this context does not imply a negative connotation but refers to the fact that multiple codons can encode the same amino acid. This is a critical feature of the genetic code.
To understand this, let’s first review the basics of the genetic code. The genetic code is composed of triplets of nucleotides, known as codons, found in messenger RNA (mRNA). Each codon specifies a particular amino acid in a protein. There are 64 possible codons (since each codon is a combination of three nucleotides, and there are four different nucleotides – adenine (A), cytosine (C), guanine (G), and uracil (U) – giving 4^3 = 64 possible combinations). However, there are only 20 standard amino acids that are incorporated into proteins during translation.
This means that there are more codons (64) than there are amino acids (20). As a result, some amino acids are encoded by more than one codon. For example:
- The amino acid leucine can be encoded by six different codons: UUA, UUG, CUU, CUC, CUA, and CUG.
- The amino acid serine can be encoded by six different codons as well: UCU, UCC, UCA, UCG, AGU, and AGC.
This redundancy allows the genetic code to be more resilient to mutations, as a mutation in the third position of a codon often results in no change to the amino acid sequence. This phenomenon is called “codon wobble” and is part of why the genetic code is robust, minimizing the impact of genetic mutations.
In summary, the genetic code is degenerate because there are more codons (64) than amino acids (20), and multiple codons can specify the same amino acid. This redundancy enhances the stability of the genetic information and allows organisms to better tolerate mutations.