Question

Discuss how degeneracy of the genetic code makes cells more robust to mutations.

Short answer

Degeneracy of codons and amino acid side chains with characteristics such as nonpolar, polar, negatively charged, or positively charged leads in a substitution type of amino acid mutation, which prevents protein formation. This mutation alters a codon to encode the same or a different amino acid, with little or no influence on the protein produced.

Step-by-step solution

Step-1: Definition

Each amino acid's genetic code is defined by a nitrogenous base, which is made up of the letters A, U, G, and C. In polypeptide synthesis, codons play a key role in starting and stopping the process.

step-2: Introduction

The nucleotides in mRNAs are read in a group of three nucleotides termed codons by the cell. During the production of polypeptides, mRNA codons are read from $5\text{'}\to 3\text{'}$ direction.

step-3: Explanation

The genetic codes are the complete collection of relationships between codons and amino acids. The genetic code is made up of 64 triplets of nucleotides, each of which, with the exception of three, encodes one of the 20 amino acids required in protein synthesis.

The code and association of amino acids with different codes have been determined thanks to the efforts of many scientists. The code was discovered to be made up of three letters (3 bases), indicating that it is a triplet code. Each of the 20 amino acids generated throughout the process is made up of three fundamental components: an amino group, a carboxyl group by COO-, and a side chain.

A property of the codon in which a single amino acid is encoded by more than one triplet is known as degeneracy of a genetic code. A nonpolar aliphatic or aromatic R group, a polar uncharged group, or a negatively or positively charged group can all be found in amino acids' side chains. All of these amino acid side chains cause changes in protein production, affecting the function and structure of the protein.

Degeneracy is evident in codon triplets when the first two letters are identical but the third letter is different in each. Aspartate (Asp) and glutamate (Glu), for example, belong to the triplets GAU and GAA, respectively. The triplet's GA block is negatively charged, and this amino acid's side chains are negatively charged R groups. Because of this genetic code degeneracy, single nucleotide substitution mutations occur, resulting in the production of amino acids that have no effect or are comparable to the specified amino acid. This mutation prevents the protein from becoming entirely nonfunctional.