The main difference between synonymous and nonsynonymous mutation is that synonymous mutation does not change the amino acid sequence of the protein, while nonsynonymous mutation changes the amino acid sequence of the protein.
Mutations are changes in the DNA sequence of an organism. They occur as a result of errors in DNA replication during cell division and exposure to mutagens or a viral infection. Synonymous mutations and nonsynonymous mutations are two forms of mutations.
Key Areas Covered
1. What is a Synonymous Mutation
– Definition, Mutations, Features
2. What is a Nonsynonymous Mutation
– Definition, Mutations, Features
3. Difference Between Synonymous and Nonsynonymous Mutation
– Comparison of Key Differences
Key Terms
Synonymous Mutation, Nonsynonymous Mutation
What is a Synonymous Mutation
Synonymous mutations are mutations that occur within a gene but do not result in a change to the amino acid sequence of the protein that the gene codes for. But they still have effects on gene expression and regulation, protein folding, and stability. These mutations occur through DNA replication errors or can be induced through exposure to mutagens such as radiation and chemicals.
One of the most common types of synonymous mutations is synonymous substitution. It is the change in the third nucleotide of a codon. The third nucleotide of a codon is mostly the least critical for specifying the amino acid. Hence, changes to this position are less likely to have an effect on the protein function. For example, the codons GCA, GCG, GCU, and GCC code for the amino acid alanine. A mutation in the third codon still results in the coding of alanine. Hence, this is a synonymous mutation.
Another type of synonymous mutation is a splice site mutation. If a splice site mutation occurs within an intron or in a position that does not affect the splicing machinery’s recognition of the site, it is still a synonymous mutation.
Synonymous mutations can also affect gene expression and regulation. The speed and efficiency of translation can be influenced by the structure and stability of the mRNA transcript, and synonymous mutations that affect these factors can therefore impact the overall rate of protein synthesis. Synonymous mutations can change the secondary structure of the mRNA transcript.
What is a Nonsynonymous Mutation
Nonsynonymous mutations are genetic mutations that occur within a gene and result in a change to the protein’s amino acid sequence that the gene codes for. These mutations can occur naturally through DNA replication errors or be induced through exposure to mutagens such as radiation or chemicals.
When a single nucleotide in a codon is changed, it results in the coding of a different amino acid. Depending on the location and the nature of the mutation, these types of mutations have a range of effects on protein function.
One type of nonsynonymous mutation is a missense mutation. Missense mutations occur when a single nucleotide change results in the coding of different amino acids. Another type of nonsynonymous mutation is a nonsense mutation, which occurs when a single nucleotide change results in the introduction of a premature stop codon, leading to the production of a truncated protein. In addition, frameshift mutation is another type of non-synonymous mutation. It occurs when one or more nucleotides are added to or deleted from the coding sequence, which results in a shift in the reading frame of the codons downstream of the mutation.
Difference Between Synonymous and Nonsynonymous Mutation
Definition
A synonymous mutation is a mutation that occurs within a gene but does not result in a change to the amino acid sequence of the protein that the gene codes for, whereas a nonsynonymous mutation is a genetic mutation that occurs within a gene and results in a change to the amino acid sequence of the protein that the gene codes for.
Mutations
Synonymous mutations do not change the amino acid sequence of the protein. In contrast, nonsynonymous mutations change the amino acid sequence of the protein.
Evolutionary Importance
Synonymous mutations are evolutionary neutral, whereas nonsynonymous mutations are evolutionary important.
Subject to Natural Selection
While synonymous mutations are not subject to natural selection, nonsynonymous mutations are subject to natural selection.
Conclusion
Mutations are changes in the DNA sequence of an organism. Synonymous mutations and evolutionary mutations are two forms of mutations. The main difference between synonymous and nonsynonymous mutation is that synonymous mutation does not change the amino acid sequence of the protein, while nonsynonymous mutation changes the amino acid sequence of the protein.
Reference:
1. “Understanding the contribution of synonymous mutations to human disease.” Nature Review Genetics.
2. “Nonsynonymous Substitution.” Science Direct.
Image Courtesy:
1. “Point mutations-en” By Jonsta247 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Missense mutations (13080807835)” By Genomics Education Programme – Missense mutations (CC BY 2.0) via Commons Wikimedia
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