6. mutations Flashcards
what are mutations
changes in the DNA that can result in no protein or an altered protein being synthesised
what are single gene mutations
involves the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides
what is substitution (gene mutation)
occurs when one base is substituted for another - these result in a change that only affects one codon
describe missense substitution (effect)
result in one amino acid being changed for another
may result in a non-functional protein or have little effect on the protein
what is nonsense substitution (effect)
results in a premature stop codon being produced which results in a shorter protein
what is splice-site substitution (effect)
if there is a substitution mutation at a splice site the some introns may be retained and/or some exons may not be included in the mature transcript
and incorrect polypeptides are produced
what is insertion (gene mutation)
when one or several base(s) is added into the DNA molecule
what is deletion (gene mutation)
when one or several base(s) is deleted from the DNA
what is a frame-shift mutation
nucleotide insertion or deletions result in frame shift mutations
they cause all of the codons and all of the amino acids after the mutation to be changed - has major effect in the structure of protein being produced
tend to be more detrimental than substitution mutations
what are chromosomal structure mutations
changes in chromosome structure involve the number or sequence of genes on a chromosome being altered
the substantial changes in chromosome mutations often make them lethal
what is deletion (chromosome structure mutation)
when a section of a chromosome is removed
what is inversion (chromosome S.M)
where a section of chromosome is reversed
what is translocation (chromosome S.M)
where a section of a chromosome is added to a chromosome, not it’s homologous partner
what is duplication (chromosome S.M)
where a section of a chromosome is added from its homologous partner
