Question

Nutritional mutations can be defined as ________.

1) those mutations that do not allow an organism to grow on minimal medium but do allow growth on complete medium
2) those mutations that change the composition of the medium
3) those mutations belonging to the group called prototrophs
4) those mutations caused by site-specific mutagenesis
5) all strains that are not auxotrophic

Answer 1

Nutritional mutations prevent growth on minimal media but allow growth on complete media by disrupting biosynthesis pathways for essential nutrients, such as certain amino acids.

Step-by-step explanation:

Nutritional mutations are defined as mutations that prevent an organism from growing on minimal medium but allow it to flourish on a complete medium. Specifically, these are mutations that hamper the biosynthesis pathway of essential nutrients, making an organism unable to produce certain necessary compounds on its own.

For instance, if a bacterium acquires a mutation that disrupts the pathway for synthesizing a particular amino acid, it becomes an auxotroph for that amino acid. In this case, the bacterium will require a complete medium that supplements the missing nutrient for growth. Researchers use techniques like replica plating to identify these nutritional mutants. They first grow the bacteria on a complete medium and then transfer them to various minimal media that lack certain nutrients. The inability of the bacteria to grow on these minimal media indicates which specific biosynthetic pathway is affected by the mutation.

Understanding these mutations is essential for grasping how certain diseases or genetic disorders may arise due to inadequate production of specific biomolecules, and how bacteria may evolve in response to their environment.