Mutations Flashcards
What are ‘Mutations’?
Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised.
What is a single gene mutation?
Single gene mutations involve the
alteration of a DNA nucleotide sequence
as a result of the substitution, insertion or
deletion of nucleotides.
State the 3 Nucleotide substitutions.
- missense mutation
- nonsense mutation
- splice-site mutations
Describe a Missense mutation?
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.
Describe a Nonsense mutation?
Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.
Describe a Splice-site mutation.
Splice-site mutations result in some exons being retained and/or some exons not being included in the mature transcript
What happens after a nucleotide insertion or deletion?
A frame-shift mutation.
Describe a frame-shift mutation?
A frame-shift mutations causes all of the codons and amino acids after the mutation to be changed. This has a major effect on the structure of the protein produced.
State the chromosome structure mutations
- Duplication
- Deletion
- Inversion
- Translocation
Describe a duplication mutation?
Duplication is where a section of a chromosome is added from its homologous partner
Describe a deletion mutation?
Deletion is where a section of a chromosome is removed
Describe an inversion mutation?
Inversion is where a section of a chromosome is reversed
Describe translocation mutation
Translocation is where a section of a chromosome is added to a chromosome, not its homologous partner
Why can chromosome mutations be lethal?
Due to substantial changes
Describe the importance of mutations and gene duplication in evolution
Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein
