6.1-cellular bontrol Flashcards
what is a mutation?
random change to genetic material.
what is a gene mutation?
random change to DNA
what are mutations associated with mitotic division called?
somatic mutations
can mutations during mitosis be passed to offspring?
no
what might mutations during mitosis be associated with?
tumours
what are the 2 main classes of DNA mutation?
point mutation
indel
what do indel mutations cause?
frameshift
what are the 3 types of point mutation?
silent
missense
nonsense
what happens during a point mutation?
one base pair is substituted for another
what happens during a silent mutation?
point mutation changes base triplet but it still codes for the same amino acid.
what enables silent mutations to happen?
genetic code is degenerate: all amino acids (apart from methionine) have more than 1 base triplet code.
what is a missense mutation?
change in the base sequence that leads to a change in amino acid sequence in a protein.
what is an example of a disease caused by a missense mutation?
sickle cell anaemia
what causes sickle cell?
valine instead of glutamic acid added to b polypeptide chain.
what happens to the blood cells of someone with sickle cell?
deoxygenated haemoglobin crystallises in them, causing them to be sickle shaped, blocking capillaries and depriving tissues of o2.
what happens during nonsense mutations?
a point mutation alters a base triplet so it becomes a stop triplet.
what happens to the proteins that are results of nonsense mutations?
truncated and dysfunctional-likely degraded within cell.
what is an example of a disease caused by a nonsense mutation?
Duchenne muscular dystrophy
what is an example of a disease caused by deletions of bases?
thalassaemia
what happens during expanding triple nucleotide repeats?
in genes which contains a repeating triplet, the number of that triplet increases.
what’s a disease caused by expanding triple nucleotide repeats?
huntingtons-repeat of CAG