U1.6 Mutations Flashcards
Define mutations.
A change in DNA which may or may not result in no protein, or an altered protein, being synthesised.
What do single gene mutations involve?
The alteration of a DNA nucleotide sequence
as a result of the substitution, insertion or
deletion of nucleotides.
Single gene nucleotide substitution mutations can be described as?
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 causes frameshift mutations?
Nucleotide insertions or deletions.
What do frameshift mutations do?
They cause all codons and therefore all amino acids after mutation site to be altered. This has a major effect on the structure of the protein produced.
Name 4 types of chromosome structure mutations.
Duplication, deletion, translocation, inversion.
Describe duplication.
Where a section of a chromosome is added from its homologous partner.
Describe deletion.
Where a section of a chromosome is removed.
Describe translocation.
Where a section of a chromosome is added to a chromosome that is not a homologous partner.
Describe inversion.
Where a section of a chromosome is reversed.
Why are changes in chromosomal mutations often bad?
They can make them lethal.
What happens to the original gene involved in a duplication mutation?
It continues to be expressed in the normal way.
