mutations

Mutation

changes in DNA that can result in no protein/an altered protein being synthesised

Single gene mutations

• involve alteration of DNA nucleotide sequence as a result of substitution

Nucleotide substitutions

• missense
• nonsense
• splice site mutations

Missense mutations

• result in 1 amino acid being changed for another
• can result in a non-functional protein being produced or have little effect on protein produced

Nonsense mutations

• result in premature stop codon produced
• results in shorter protein produced

Splice site mutations

result in some introns being retained (and/or) some exons not being included in mature (RNA) transcript

Frameshift mutations

• cause all codons and amino acids after mutation to be changed
• has major effect on structure of protein produced
• result of insertion or deletion

Chromosome structure mutations

involves alteration to structure

• duplication
• deletion
• inversion
• translocation
  large changes in chromosome mutations often make them lethal

Duplication mutations

section of chromosome added from its homologous partner

deletion mutations

section of a chromosome is removed

• result in frameshift mutations

inversion mutations

section of chromosome is reversed

translocation

section of chromosome added to a chromosome

Why is mutation and gene duplication important in evolution

• duplication allows potential beneficial mutations to occur in a duplified gene whilst original gene can still be expressed to produce its protein