Question

Two persons differ in several SNPs (single nucleotide polymorphisms), however, after their proteins are compared, you realize that only some SNPs induce changes in amino acid sequence. What is going on here? How come some SNPs induce amino acid change while others don't? (GENETICS QUESTION)

Answer 1

The answer to your query is as follows:

Two persons differ in several SNPs (single nucleotide polymorphisms), however, after their proteins are compared, we realize that only some SNPs induce changes in amino acid sequence. Only some SNPs induce amino acid change while others do not.

Single nucleotide polymorphism or SNP can be defined as a change in a single or one nucleotide in the DNA sequence. It can also be defined as a base-pair change that occurs within a codon in the DNA.

A SNP can change the way a gene is transcribed on the basis of its location in the sequence. Thus, can alter the amino acid sequence for the protein made in the translation process.

Single nucleotide polymorphism are of two types in the coding region are:

• Synonymous SNPs
• Nonsynonymous SNPs

Synonymous SNPs do not affect the protein sequence formed while the nonsynonymous SNPs affect the amino acid sequence of protein formed in translation.

But sometimes in some cases the SNPs within a DNA coding sequence do not change the amino acid sequence of the protein that will be formed in the translation process. It is due to the property of the genetic code which states the degeneracy of the genetic code. According to degeneracy of genetic code, a single amino acid can be coded by more than one codon because there are 64 codons which codes for 20 amino acids.

A change in one nucleotide in the SNP sometimes may not induce amino acid change because the nucleotide changed can also cause the same amino acid to be coded from the new DNA codon formed after polymorphism. Thus, a silent mutation can lead to a change in the codon by changing one of the letters in the triplet code but despite this single nucleotide change, the amino acid coded for this codon remains unchanged due to the degeneracy of the genetic code.

Hope it helps!