gene mutations Flashcards
(8 cards)
substitution of bases
a nucleotide section of DNA molecule is replaced by another nucleotide that has a different base
consequences of substitution
-the formation of one of three stop codons that mark the end of polypeptide chain
the polypeptide chain would be stopped prematurely
protein function wouldnt function correctly
-formation of a codon coding for another amino acid meaning that the structiure of the polypeptide produced would differ in a single am,ino acid
-the formation of a different codon but one that codes for the same amino acid as before dude to the degenerate nature of the genetic code
deletion of bases
the loss of a single nucleotide base from DNA sequence
effect of deletion
causes a frame shift because the whole sequence shifts to the left by one letter- the gene is now read in the wrong triplets and coded information is altered most triplets will be different therefore most amino acids coded for will be different (not all due to degenerate nature of code) the polypeptides will be different and lead to the formation of a non functional protein that could considerably alter the phenotype.
if a base near the end of the sequence is deleted its likely to have little effect
addition of bases mutation and consequences
an extra base becomes inserted in the sequence
this usually has a similar effect to a deletion- frame shift and whole sequence of triplets becomes altered
inversion mutation
a section of the sequence detaches and reattaches back to front
this results in different amino acids being coded for by this region.
duplIcation mutation
one base is duplicated at least once in the sequence. this causes a frame shift to the rIght and a different sequence of amino acids are coded for.
translocation mutation
a section of bases on one chromosome detaches and attaches onto another chromosome causing significant impacts on gene expression and resulting phenotype
