Question

Examining a pathway inside a cell, you determine the following:

A+ B --> C + D

Which of the follow statements is / are true. (Select all that apply)

Possible rate limiting step.

Step is in equilibrium.

Step does not require energy.

Likely point of regulation.

Increasing D will decrease C.

Answer 1

the following statements are true :-

• possible rate limiting step-because it is unidirectional i.e. irreversible and since, nothing is mentioned about the speed of the reaction i.e. whether it is a slow step or a fast step, we can assume it to be the slowest committed step.
• step does not require energy- because in the above equation nothing is mentioned about energy involvement in the form of ATP OR GTP since these are the energy currency of the cell and the following reaction which is a part of a mechanism is taking place inside the cell.
• likely point of regulation- this can be the equation which is the regulatory step in the entire mechanism as it can be the first committed step of the mechanism. It is a general rule of metabolic regulation that pathways are regulated at the first committed step which might be applicable here.