Single gene mutations Flashcards
What is missense substitution?
When one amino acid is swapped for another, making an altered protein which may be abnormal or non-functioning, or may not be affected
What is nonsense substitution?
A codon that’s used to code for an amino acid becomes a STOP codon.
Protein synthesis is stopped early, and a shorter polypeptide chain is produced
What happens to the subsequent triplets after insertion?
They are read incorrectly
What does single gene mutations involve?
A change in one base pair, which alters the DNA nucleotide sequence
What are the three types of single gene mutations?
Substitution, insertion and deletion
What happens in substitution?
When one nucleotide is swapped for a different one
What happens in insertion?
A nucleotide is added into a DNA molecule and all the subsequent triplets are read incorrectly
What type of mutation is insertion and deletion?
Frameshift mutation
Why is deletion and insertion frameshift mutations?
As the whole line of code moves along one place, altering all subsequent amino acids. It results in serious errors in any protein produced.
What happens in deletion?
A nucleotide is removed from a DNA molecule and all the subsequent triplets are read incorrectly and
Where do splice site mutations occur?
Where introns meet exons at splice sites
What do splice site mutations result in?
An intron being retained in error, and the mature mRNA transcript being faulty
Give an example of a disease caused by splice site mutations
Beta thalassaemia
