cellular control Flashcards
what are the three types of gene mutation
misense
silent
nonsense
what is a silent mutation
when a point mutation causes a change to a base triplet, and still codes for the same amino acid
no effect
no alteration of protein structure and can doesnt affect its function
what does it mean if a amino acids are degenerate
when amino acids can be coded for by several base triplet codes
therefore if a point mutation occurs to the nucleotide base triplet, it still codes for the same amino acid
what does it mean if a gene is non overlapping
codons are read as separate units, each base is only part of one codon
what is a missense mutation
change to base triplet sequence which leads to change in amino acid sequence
what is a nonsense mutation
alters base triplet and places AUG codon which is termination of codon
creates a non functioning protein
what genetic disease is caused by a nonsense mutation
duchenne muscular distrophy
what is duchenne muscular distrophy
progressive muscle weakness caused by nonsense mutations
what causes a frameshift
when individual nucleotides are added or deleted from a gene, ALL BASE TRIPLETS ARE ALTERED.
are all mutations harmfull
no some are beneficial or neutral
what base triplet codes for a stop
AUG
what are the two main classes of dna mutation
point mutations- one base pair replaces another base pair
Insertion or deletion- nucleotides are inserted/ deleted from a dna length causing a frameshift
what mutation causes sickle cell anaemia
missense- when a mutation occurs to a base triplet and it actually changes the amino acid sequence
when mutations occur in ————- processes, it can be inherited by offspring
mutations occur in meiosis or gamete formation, it can be inherited in offspring
why do insertions/ deletions cause a frameshift
because the genetic code is NON OVERLAPPING, and read in triplets.
Therefore the insertion/ deletion of just one base, will alter how the gene is read. altering all triplets and the structure and function of a polypeptide.
