Single Gene Mutations

Introduction

• Single gene mutations are specific types of genetic changes that occur within a single gene.
• These mutations involve alterations in the DNA nucleotide sequence of a gene.

Types of Single Gene Mutations

1. Substitution Mutations

• Involves the replacement of one nucleotide with another within a DNA sequence.
• Substitution mutations can lead to the following outcomes:
  • A change in the amino acid encoded by the affected codon, which may or may not affect protein function.
  • No change in the amino acid due to the degeneracy of the genetic code.
  • A premature stop codon, resulting in a non-functional protein.

2. Insertion Mutations

• Occur when one or more nucleotides are added to a DNA sequence.
• This can lead to a shift in the reading frame, affecting the entire protein's amino acid sequence.
• Frameshift mutations can significantly alter protein function.

3. Deletion Mutations

• Involve the removal of one or more nucleotides from a DNA sequence.
• Like insertion mutations, deletions can cause frameshifts and alter the protein's amino acid sequence.

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Single Gene Mutations

Causes of Single Gene Mutations

• Single gene mutations can be caused by various factors, including:
  • Spontaneous mutations: Random errors during DNA replication.
  • Environmental factors: Exposure to mutagenic agents such as radiation or chemicals.
  • Inherited mutations: Passed from one generation to the next.

Impact of Single Gene Mutations

• The consequences of single gene mutations depend on the type and location of the mutation within the gene.
• Some mutations have no noticeable effect, while others can lead to genetic disorders or diseases.
• Mutations that affect essential genes can be lethal.

Summary

Single gene mutations involve alterations in the DNA nucleotide sequence of a gene and can result from substitutions, insertions, or deletions of nucleotides. These mutations can have varying impacts on protein function, and their effects depend on factors such as the type and location of the mutation within the gene.