L23- Genetic Variations and Mutation Flashcards
what are mutations?
they are permanent changes in the DNA sequence and can cause change in the base sequence on the mRNA therefore causing change in protein produced and can also cause genetic disease.
what are the 4 types of mutation?
1) point mutation
2) missense mutation
3) frame shift mutation
4) splice site of mutation
explain what’s meant by point mutation?
its the substitution of a single base and have 2 types
transition: purine substituted with another purine
transversion: purine and another pyrimidine
what are the consequences of point mutation?
1) silent mutation
2) missense mutation
3) nonsense mutation
what is silent mutation?
its when the changed/substituted base in the codon codes for the same amino acid
what is missense mutation?
when the codon containing the substituted base codes for a different amino acid can be as follow
1) acceptable
2) partially acceptable
3) non acceptable
what is acceptable missense mutation?
when the protein contains a substituted amino but functions normally
like lysine asparagine in hemoglobin
what is partially acceptable missense mutation?
glutamic cud substitute with valine causing sickle cell anemia, functions normally but not in low levels of oxygen.
what is unacceptable missense mutation?
when the protein is fully non-functioning like
histidine is change with tyrosine casein Hb M cannot transport oxygen and only treatment is regular blood transfusions
what is non-sense mutation?
when the codon containing the base. substitution have changed to become stop codon preventing further translation of mRNA and producing truncated protein
what is frame shift mutation?
it results due to the insertion or deletion off or multiple nucleotides leading to the formation of a completely different protein
what is trinucleotide repeat expansion?
give an example
a sequence of 3 bases that are repeated in tandem will become amplified producing a protein with 1 too many repeated amino acid
EXAMPLE:
the repetition of CAG in exon 1 of hungtion protein causes many glutamine amino acids to be found in the protein and causing neurodegenerative disorder called hungtion disease.
what is splice site mutation?
mutation occurring at the site of splicing the primary transcript can alter the way in which introns are cut and produce aberrant proteins.
what is polymorphisms?
change in the genotype with no change in the phenotype or nor harmful change in genotype. polymorphisms makes patients more susceptible to a disease or rarely causes the disease have 2 types
single base change
tandem repeats.
