Question

You expose the roundworm, C. elegans, to the intercalating agent, acridine orange.

(a) What physical type of mutation is most likely to occur in the germ cells of the treated worms? Briefly explain why this type of mutation is most likely?

(b) If this mutation occurs in a coding region of the genome, is it more likely to act at the molecular level as a missense, nonsense, silent, or frameshift mutation, or some combination of those possibilities? Briefly explain.

Answer 1

a) Being cell-permeable, the acridine orange interacts with DNA by intercalation and RNA by electrostatic attractions. These molecules that can intercalate between the bases cause frameshift mutations which may further lead to disruption in protein synthesis.

b) Generalliy in case of frameshift mutation, any mRNA produced from a mutated DNA sequence may get read out of frame after the point of the insertion or deletion. This may yield a nonsense protein. This frameshift mutation can may also produce a termination codon. Frameshift mutations are less deleterious if they are close to the carboxyl terminal.