Question

Francois Jacob and Jacques Monod studied Escherichia coli (E. coli) bacteria by using lab experimentation. What revision to their initial hypothesis did they come up with?

A. The lac operon is repressed by allolactose.
B. E. coli are unable to process lactose sugar.
C. All E. coli operons are always turned on.
D. Two operons control bacterial respiration.

Answer 1

Jacob and Monod revised their initial hypothesis regarding the lac operon in E. coli. The correct revision to their hypothesis is that two operons control bacterial respiration. The correct answer is option D.

Step-by-step explanation:

Jacob and Monod revised their initial hypothesis regarding the lac operon in E. coli. Originally, they hypothesized that E. coli are unable to process lactose sugar. However, through their experiments, they discovered that the lac operon is repressed by a protein known as the repressor when lactose is not present.

When lactose is not present and the repressor is bound to the operator, They found that when lactose is present, an end product of lactose metabolism called allolactose binds to the repressor, preventing it from binding to the operator.

This allows RNA polymerase to bind to the promoter and transcribe the genes responsible for lactose metabolism. Therefore, the correct revision to their initial hypothesis is D. Two operons control bacterial respiration.