Question

What does it mean to say that the genetic code is degenerate?

Short answer

Answer: The genetic code is considered degenerate because multiple codons can specify the same amino acid in a protein. This property provides redundancy in the genetic code, which can be beneficial in maintaining protein function even if mutations occur in DNA sequence. For example, the amino acid leucine can be encoded by any of the six different codons: UUA, UUG, CUU, CUC, CUA, or CUG.

Step-by-step solution

Introduction to the Genetic Code

The genetic code is a set of rules that translates a sequence of three nucleotides in DNA (called a codon) into a specific amino acid. Amino acids are the building blocks of proteins, which are essential for the structure, function, and regulation of living organisms. There are 64 possible codons (4 nucleotides with 3 positions, 4^3 = 64) but only 20 common amino acids, which means that more than one codon can encode for the same amino acid. This property is known as degeneracy.

Degeneracy of the Genetic Code

When a genetic code is degenerate, it means that multiple codons can specify the same amino acid in a protein. This feature provides redundancy to the genetic code, which can be beneficial in maintaining protein function even if mutations occur in DNA sequence.

Examples of Degeneracy

To better understand the degeneracy of the genetic code, let's consider some examples. The amino acid leucine can be encoded by any of six different codons: UUA, UUG, CUU, CUC, CUA, or CUG. Similarly, the amino acid serine is encoded by six different codons: UCU, UCC, UCA, UCG, AGU, or AGC. On the other hand, some amino acids such as methionine (AUG) and tryptophan (UGG) are encoded by just one codon.

Significance of Degeneracy

The degeneracy of the genetic code offers several advantages. Firstly, it decreases the negative impact of mutations since some changes in the DNA sequence will still result in the same amino acid, reducing the likelihood of harmful changes to the protein's structure or function. Secondly, it allows slight variations in the DNA sequence to occur without affecting the protein, which can be beneficial for evolution by providing flexibility for the development of new functions or improvements in existing ones.