Mutations (KA6)

Key Area 6

Definition of mutations

Mutations are change in the DNA that can result in no protein or an altered protein being synthesised

Two type of mutations are

Single gene and chromosome

Definition of single gene mutations

Single gene mutation involve alteration of DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides

Definition of substitution mutation

Nucleotide substitution is when one base is substituted for another in the DNA sequence

Three types of substitution mutations are

Missense, nonsense, splice site

What can missense mutations result in

Result in one amino acid being changed for another. This may result in non functional protein or have little effect on the protein

What can nonsense mutations result in

Result in a premature stop codon being produced which results in a shorter protein

What can splice site mutation result in

Result in some introns being retained and some exons not being included in the mature transcript

What can substitution be described as

A point mutation as it only affects one point of the protein

Definition of insertion in frameshift mutation

When a nucleotide is inserted into the sequence

Definition of deletion in frameshift mutation

When a nucleotide is deleted from the sequence

What are the two type of frameshift mutation

Insertion and deletion

What does frameshift mutation cause

All of the codons and all the animo acids after the mutation to be changed

What are the four types of chromosome mutations

Duplication, deletion, inversion and translocation

Definition in duplication in chromosome mutation

Is where a section of a chromosome is added from its homologous partner

Definition of deletion in chromosome mutation

Is where a section if a chromosome is removed

Definition of inversion in chromosome mutation

Is where a section of chromosome is reversed turned 180°

Definition of translocation in chromosome mutation

Is where a section of chromosome is added to a chromosome not its homologous partner

Why are duplication mutations important

Duplication allows potential beneficial mutations to occur in duplicated gene whilst the original gene can still be expressed to produce its protein

Name a gene mutation which causes a frameshift

Deletion

Name the type of mutation caused by substitution of a nucleotide that results in a different amino acid

Missence

Name the type of mutation caused by substitution that produces a stop codon

Nonsense

Name the type of mutation caused by insertion or deletion of nicleotides

Frameshift

Describe what happens during an insertion single-gene mutation

One nucleotide is added to the DNA sequence