Gene mutation

Mutation

A permanent change in the DNA

When do mutations happen

When a gamete forms or during cell division

What is the effect of a mutation

Creates a different R group which causes the structure of the protein to change

Types of mutations

Inversion

Substitution

Deletion

Insertion

Inversion

Two bases switch place

Substitution

One base is swapped for another

Deletion

A base is completely removed

Insertion

An extra base is added

Silent mutation

When the amino acid formed doesn’t change even though a codon changed

Chromosomal mutations

Translocation

Inversion

Duplication

Deletion

Aneuploidy

Translocation

A segment of one chromosome moves to a different chromosome

Inversion

A segment of the chromosome breaks off, flips and reattaches causing gene to change locus

Duplication

A segment of a chromosome is copied and attached

Deletion (chromosomal mutation)

A segment of a chromosome is removed

How does a cell fix a mutation

The mismatch is detected

The strand is cut using enzymes

DNA polymerase replaces nucleotides

DNA ligase seals the gaps

Why could a mutation not have an effect

It’s in non coding DNA

The code is degenerate

Two type of aneuploidy

Monsomy and trisomy

Monosomy

There is one less chromosome

Trisomy

There is a extra chromosome

Sickle cell disease

Reuslts from a mutation in the gene for haemoglobin in the gametes

What happens to haemoglobin in sickle cell disease

Haemoglobin forms rigid rods that causes red blood cells to change shape reducing their surface area and flexibility

Thalasseamia

Causes protein chains in haemoglobin to be made incorrectly which cause red blood cells to change shape reducing their oxygen capacity

What is the cause of mutations

Mutagens such as X-rays and certain chemicals