Mutations!!

What are mutations?

Changes in the DNA that can result in no protein or an altered protein being synthesised

What are single gene mutations?

Mutations that involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides

What does a substitution mutation mean?

It means that one nucleotide is substituted for another and an incorrect amino acid may be inserted into protein

How are insertion mutations caused?

They are caused by the addition of one or more nucleotides into a section of DNA

What does a deletion mutation refer to?

The removal of one or more nucleotides from the DNA

What are effects of a substitution mutation?

• Missense

• Nonsense

• Splice site

What do missense mutations result in?

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

What do nonsense mutations result in?

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

What do splice-site mutations result in?

Some introns being retained and/or some exons not being included in the mature transcript

What is the effect of insertion and deletion mutations?

Frame shift mutations

What do frame shift mutations cause?

All of the codons and all of the amino acids after the mutation to be changed this has a major effect on the structure of the protein produced

Chromosome structure mutations?

• Duplication

• Deletion

• Inversion

• Translocation

What is duplication?

Where a section of a chromosome is added from its homologous partner

What is deletion? (chromosome structure)

Where a section of a chromosome is removed

What is inversion?

Where a section of a chromosome is reversed

What is translocation?

Where a section of a chromosome is added to a chromosome, not its homologous partner

The substantial changes in chromosome mutations often make them….?

Lethal

What do duplications allow?

Potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein