unit one - mutations Flashcards
what are mutations?
changes in the DNA that can result in no protein or an altered protein being synthesised
what is a single gene mutation?
they involved the alteration of a DNA sequence
what are examples of single-gene mutations?
substitution, insertion and deletion of nucleotides
what are missense mutations?
they result in one amino acid being changed for another, this may result in a non-functional protein or have little effect on it.
what are nonsense mutations?
result in a premature stop codon being produced which results in a shorter protein
what is a splice-site mutation?
results in some introns being retained or some exons not being included in the mature transcript
what do nucleotide insertions or deletions result in?
frameshift mutations
what are frameshift mutations?
cause of all codons and all amino acids after the mutation to be changed, this has a major effect on the structure of the protein.
what are examples of chromosome structure mutations?
duplication, deletion, inversion and translocation
what are duplication mutations?
where a section of a chromosome is added from its homologous partner
what are deletion mutations?
where a section of a chromosome is removed
what is an inversion?
where a section of a chromosome is reversed
what is translocation?
where a section of a chromosome is added to a chromosome, not its homologous partner.
what do these substantial changes do?
they often make them lethal
why are mutations and gene duplication important in evolution?
duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein.
