Question

A gene has the base sequence CGT AT. What is an example of a frameshift mutation on this gene?

Answer 1

See below :)

Explanation:

First, we should know what a frameshift mutation is!

Frameshift mutations are insertions or deletions of nucleotides in DNA that change the reading frame (the grouping of codons). Recall that a codon is a group of 3 nucleotides that corresponds with a specific amino acid. Thus, if the codon is changed, then the amino acid sequence will change, and the translated protein will not function properly.

It is important to note that frameshifts only occur if the insertion or deletion of nucleotides is not a multiple of 3. Since codons are read in groups of 3, an insertion of 3 or 6 would not cause a shift in the positions of all subsequent nucleotides.

It is also possible that the mutated code contains an early stop codon (UAA, UAG, or UGA) and stops translation early, resulting in an abnormally short polypeptide.

There are an unlimited number of frameshift mutations you could do on the sequence of CGT AT. You could add/delete one A, C, T, or G, or you could add/delete 2, 4, 5 nucleotides...

Here are some examples!

• Add an extra T:
  TCG TAT
• Add an extra T at a different position:
  CTG TAT
• Delete the G:
  CTA T
• Add 2 Gs:
  CGG GTA T

Hope this helps!