1. Mutations and Mutagenic Agents

Mutation definition

Any change to the base sequence of DNA

List of all the types of mutations that can occur: 6

Substitution - one or more bases swapped for another

Deletion - one or more bases are removed

Addition - one or more bases are added

Duplication - one or more bases are repeated

Inversion - a sequence of bases is reversed

Translocation - a sequence of bases is moved from one location in the genome to another.

Genetic disorders

Inherited disorders caused by abnormal genes or chromosomes e.g. cystic fibrosis.

hereditary mutations

When a gamete contain a mutation for a genetic disorder is fertilised, meaning the mutation will be present in the new fetus, passed off to offspring.

Degenerate

Some amino acids are coded for by more than one codon.

frameshift definition and the type of mutations that always cause this:

Additions, duplications and deletions within a gene which will almost always change the amino acid sequence of a polypeptide.

Mutagenic agents

examples

Things that can increase the rate of mutations

ultraviolet radiation, ionising radiation, some chemicals

What are the three ways mutagenic agents can change the base sequence of DNA to cause mutations?

1. Acting as a base - chemicals called base analogs can substitute for a base during DNA replication, changing the base sequence in the new DNA.

2. Altering bases - some chemicals can delete or alter bases.

3. Changing the structure of DNA - causes problems in DNA replication