8.1.2 The Effect of Genetic Mutations

Effects of Mutations

1. Neutral Mutations

• No change to the organism's phenotype or survival.
• Occurs when:
• The mutation is in a non-coding region of DNA (e.g., introns).
• The mutation is a silent mutation, where the codon changes but the amino acid remains the same due to the degenerate nature of the genetic code.
• The protein's tertiary structure is altered, but its function is unaffected.

2. Beneficial Mutations

• Provide an advantage to the organism, improving survival or reproduction.
• Example: The evolution of trichromatic vision in humans allows better differentiation of colours, advantageous in identifying food and avoiding danger.
• Beneficial mutations are a key driver of natural selection and evolution.

3. Harmful Mutations

• Result in a disadvantage to the organism, often leading to disease or reduced survival.
• Example:
• Mutation in the CFTR gene produces a non-functional protein, causing cystic fibrosis, a disorder affecting the respiratory and digestive systems.
• Mutations in tumour suppressor genes like p53 can lead to uncontrolled cell division and cancer.