Question

________ have lost, through ________, the ability to grow on minimal medium.

A) prototrophs; adaptation
B) mutants; adaptation
C) prototrophs; mutation
D) auxotrophs; mutation
E) auxotrophs; adaptation

Answer 1

Auxotrophs are nutritional mutants that have lost the ability to grow on minimal medium due to a mutation. The answer is D) auxotrophs; mutation. These mutants are identified using replica plating.

Step-by-step explanation:

The organisms that have lost, through mutation, the ability to grow on minimal medium are called auxotrophs. Auxotrophs are nutritional mutants with a loss-of-function mutation in a gene encoding the biosynthesis of a specific nutrient such as an amino acid. The correct answer to the question is D) auxotrophs; mutation.

The identification of these auxotrophic mutants is often conducted through a process known as replica plating. This technique allows researchers to detect bacteria that can grow on a nutritionally complete medium but fail to grow on a medium lacking a specific nutrient, indicating the presence of a mutation in the synthetic pathway for that nutrient. For further study, cells from the corresponding colony on the nutritionally complete plate are used to recover the mutant.