Question

. Identify the type of POINT mutation (BASE SUBSTITUTION or frameshift mutation)in the following gene, also identify if it results in a silent, missense or nonsense mutation.

A. Template strand 3’ GGG TAC CCA ATG AAC CAA ACT AGC 5’

B.Write mRNA sequence

C.Write amino acid sequence

D.Now, Replace the base “C” (7th letter from 3’ end) with the base “A”

E.Write mutated gene 3’

F.Write mRNA sequence:

G.Amino acid sequence:

H.Identify if it is a base substitution or a frameshift mutation? __________________________.

I. What is the effect of this mutation (silent or missense or nonsense) ____________________

Answer 1

A ) Template strand 3’ GGG TAC CCA ATG AAC CAA ACT AGC 5’

B) mRNA is complementary to the template strand, A is complementary to T and U is complementary to A and G is complementary to C and vice versa.

mRNA sequence is

5`-CCCAUGGGUUACUUGGUUUGAUCG-3`

C) the amino acid sequence is obtained using codon table.

the mRNA has open reading frame the amino acid sequence is

Met-Gly-Tyr-Leu-Val-STOP

D and E) template strand with the mutation is

Template strand 3’ GGG TAC ACA ATG AAC CAA ACT AGC 5’

F) mRNA is complementary to the template strand, A is complementary to T and U is complementary to A and G is complementary to C and vice versa.

mutated mRNA is

5`-CCCAUGUGUUACUUGGUUUGAUCG-3`

G) amino acid sequence is obtained using codon table.

Met-Cys-Tyr-Leu-Val

H) this is a point mutation, point mutation is caused by base substitution the 7 th nucleotide is replaced with A.

( frameshift mutations change the reading frame. frameshift mutations are caused by insertion or deletion of nucleotides which are not in the multiples of three)

I) missense mutation: point mutation which changes one codon to another so the amino acid also changes.

Nonsense mutation: point mutation which changes one codon to stop codon.

silent mutation: point mutation which changes one codon to another but the amino acid does not change.

here the mutation is Missense mutation.