alteration of bases

Question 1

what is a mutation

Answer 1

an alteration to the DNA base sequence

often arise spontaneously during DNA replication

Question 2

what are addition and deletion mutations

Answer 2

where one or more nucleotides (bases) are either inserted or deleted from the DNA sequence

Question 3

what is substitution mutation

Answer 3

where one nucleotide (base) in the DNA sequence is replaced by another

Question 4

what is a duplication mutation

Answer 4

where one or more nucleotides (bases) duplicate and repeat

Question 5

what is an inversion mutation

Answer 5

where a group of nucleotides (bases) become separated from the DNA sequence, then rejoin in the reverse order

Question 6

what is a translocation mutation

Answer 6

where a group of nucleotides (bases) become separated from the DNA sequence, and are then inserted into the DNA of a different chromosome

Question 7

which mutations are most likely to have an impact

Answer 7

insertion, deletion, duplication and translocation

• produce a frameshift - entire amino acid sequence produced will be different

Question 8

which mutations are most likely to have a smaller impact and why

Answer 8

substitution, inversion

• they only alter one or very few triplets
• the amino acid sequence may not be affected due to degenerate nature of the genetic code

Question 9

what is a mutagenic agent

Answer 9

factors that increase the rate of gene mutations

chemical mutagens eg alcohol

ionising radiation eg UV