Question

Assume that you are working with a mutant, nutritionally deficient strain of Escherichia coli and that you isolate "revertants," which are nutritional-normal. Describe, at the molecular level, two possible causes for the "reversion to wild type."

Answer 1

At the molecular level, reversion to wild-type in nutritionally deficient E. coli can occur through a back mutation, restoring the ability to produce a necessary nutrient, or a suppressor mutation, which bypasses the block caused by the original mutation.

Step-by-step explanation:

When working with a mutant, nutritionally deficient strain of Escherichia coli and isolating revertants that are nutritionally normal, two possible molecular causes for the reversion to wild-type are back mutation or suppressor mutation.

Firstly, a back mutation could occur, which is a second mutation that restores the original DNA sequence or results in a new sequence that somehow compensates for the effect of the original mutation, allowing the E. coli to revert to being able to synthesize the nutrient it was previously unable to produce.

Secondly, a suppressor mutation may arise in a different location within the genome that counteracts the original mutation's effect. This does not reverse the original mutation but provides a new pathway or enzymatic function that bypasses the block created by the original mutation, allowing the cell to grow without the required nutrient supplement.

Answer 2

Mutation may be defined as the sudden heritable change in the genetic sequence of the organism. The mutation can cause the characteristics phenotype in the individual.

Two ways by which the reversion to wild type occur are true reversion and suppression mutation. The true reversion process involves the precision of the correction of the original mutation. The suppression intragenic or intergenic mutation introduce the changes in the mutant gene and compensate for the wild type product.