Saturday Genetics Quiz #13: Types of Mutations

This week’s question:

What are some of the major types of mutations/DNA alterations?

Answer:

A single base pair change is called a point mutation and directly affects the function of a single gene and can be categorized into:

• Missense mutation – results in a protein in which one amino acid is substituted for another

• Nonsense mutation – a stop codon replaces an amino acid codon, leading to premature termination of translation

• Frameshift mutation – causes a change in the reading frame leading to introduction of unrelated amino acids into the protein, generally followed by a stop codon

Small deletions of a few base pairs also affect single genes and can cause frameshift mutations or mutations which lead to the loss of amino acids.

Chromosomal mutations affect overall chromosome structure and involve multiple genes, often resulting in major physiological changes. Genes may be deleted or inserted, inverted, or exchanged between chromosomes.

For more information about mutations, see Molecular Cell Biology by Harvey Lodis et al.