Question

1. Find the longest open reading frame in the following coding strand sequence and then transcribe and translate i

ATGTGAATCTGATATGCTTAGCTTCGATGCATCAACGTAATCTATAGATACGATCGACTAC

2. The third nucleotide of the fifth codon was mutated to a G – what sort of mutation is this?

3. What if the 2nd nucleotide of the seventh codon were mutated to an A?

Answer 1

1) ATGTGAATCTGATATGCTTAGCTTCGATGCATCAACGTAATCTATAGATACGATCGACTAC

the longest open reading frame is given in bold, the reading frame starts from the second nucleotide.

the amino acid sequence is

Met-Leu-Ser-Phe-Asp-Ala-Ser-Thr

2) ATGTGAATCTGATATGCTTAGCTTCGATGCGTCAACGTAATCTATAGATACGATCGACTAC

Met-Leu-Ser-Phe-Asp-Ala-Ser-Thr

the amino acid does not change so this is a silent mutation,

silent mutations are point mutation which does not change the amino acid sequence.

3) ATGTGAATCTGATATGCTTAGCTTCGATGCATAAACGTAATCTATAGATACGATCGACTAC

Met-Leu-Ser-Phe-Asp-Ala-

the seventh nucleotide has changed to a stop codon, so this is a nonsense mutation, a point mutation that creates a premature stop codon.