how the alteration in any of codons results in mutation

Answer 1

A mutation occurs when there is a change in the nucleotide sequence of DNA, leading to an alteration in the coding sequence of a gene. This alteration can be caused by changes in one or more codons, which are the three-nucleotide sequences that specify a particular amino acid during protein synthesis.

There are three main types of mutations that can occur in codons:

1. Silent mutation: This type of mutation involves a change in the DNA sequence within a codon, but the resulting codon still codes for the same amino acid. In this case, the mutation does not lead to any change in the protein's structure or function. Silent mutations are often caused by a change in the third base of a codon, which does not affect the amino acid specified.

Example:
Original codon: ACC (codes for threonine)
Mutated codon: ACU (also codes for threonine)

2. Missense mutation: This type of mutation involves a change in the DNA sequence within a codon, which leads to a different amino acid being incorporated into the protein chain. Missense mutations can have varying effects on protein function, ranging from mild to severe, depending on the significance of the altered amino acid.

Example:
Original codon: CAC (codes for histidine)
Mutated codon: CAA (codes for glutamine)

3. Nonsense mutation: This type of mutation involves a change in the DNA sequence within a codon, which leads to the creation of a premature stop codon. This premature stop signal causes the synthesis of a truncated protein that is usually non-functional. Nonsense mutations often result in severe effects on protein function.

Example:
Original codon: CGA (codes for arginine)
Mutated codon: TGA (stop codon)

It is important to note that the consequence of a mutation depends on factors such as the location of the gene within the genome, the role of the affected protein, and the specific alteration in the amino acid sequence. Additionally, mutations can also occur outside of coding regions, such as within regulatory regions or non-coding RNA molecules, leading to diverse effects on gene expression and function.