Question

11. What effect does an insertion mutation have on the mRNA reading frame, give an example?

Answer 1

Insertion means addition of a new nucleotide.

If one or two bases are added, then the whole amino acid sequence is changed. If 3 bases are added then one new amino acid is introduced and of the amino acids remain same.

Example,

Wild type mRNA sequence,

5'- AUG CGU AGC GAA UAU UUA -3'

Wild type amino acid sequence will be ,

N- met arg ser glu tyr leu -C

Case 1 - insertion of A at postion 10

5'- AUG CGU AGC AGA AUA UUU A -3'

Mutated protein, N- met arg ser arg ile phe -C

Case 2 - insertion of AG at position 10 and 11 respectively

5'- AUG CGU AGC AGG AAU AUU UA -3'

Mutated protein, N- met arg ser arg asn ile -C

Case 3 - insertion of AGU at position 10, 11 and 12 respectively

5'- AUG CGU AGC AGU GAA UAU UUA -3'

Mutated protein, N-met arg ser ser glu tyr leu -C

In this last case, serine is inserted, rest will remain same.

Please rate.

Mutations are given in bold.