In a bacterium that is normally cylindrical in shape, loss of either of two genes A and B results in round cells. Additionally, gain-of-function mutations in gene A can rescue the phenotype of gene B loss-of-function mutants. What phenomenon best describes this observation? The product of which gene is more likely to function upstream of the other one in determining cell shape in this bacterium?
A) Suppression; gene A
B) Suppression; gene B
C) Complementation; gene A
D) Complementation; gene B

Question

Quizplus · Accepted Answer

The gain-of-function mutations in gene A suppress the loss-of-function mutations in gene B, suggesting that the product of gene A functions further downstream.

In a Bacterium That Is Normally Cylindrical in Shape, Loss