Feedback regulation ensures the appropriate activity from an enzyme when it’s needed.

Feedback regulation of an enzyme occurs when a product of the reaction binds to an allosteric site on the enzyme and affects its catalytic activity. Through feedback inhibition, the cell responds to the amount of reaction product in order to regulate its further production. The higher the concentration of the final product, the more likely that product will bind to the allosteric site of the enzyme, shutting down that pathway.

This effect can be positive or negative/inhibitory. Negative feedback results in the inhibition of an enzyme in a biochemical pathway, reducing the activity of earlier enzymes, and stopping the pathway. Positive feedback results in the activation of more enzymes, thus increasing its production of the product.

 

Practice Questions

MCAT Official Prep (AAMC)

Practice Exam 3 B/B Section Question 57

Practice Exam 4 B/B Section Passage 2 Question 17

Practice Exam 4 B/B Section Passage 6 Question 36

 

Key Points

• Feedback regulation of an enzyme occurs when a product of the reaction binds to an allosteric site on the enzyme and affects its catalytic activity.

• Through feedback inhibition, the cell responds to the amount of reaction product in order to regulate its further production.

• Negative feedback results in the inhibition of an enzyme in a biochemical pathway, reducing the activity of earlier enzymes, and stopping the pathway.

• Positive feedback results in the activation of more enzymes, thus increasing its production of the product.

Key Terms

Feedback regulation: A process by which the product of a metabolic pathway influences its own production by controlling the amount and/or activity of one or more enzymes involved in the pathway.

Allosteric Site: The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of the enzyme and influencing its ability to be active

Feedback inhibition: The phenomenon where the output of a process is used as an input to control the behavior of the process itself, oftentimes limiting the production of more product

Negative feedback: Results in the inhibition of an enzyme in a biochemical pathway, reducing the activity of earlier enzymes, and stopping the pathway.

Positive feedback: Results in the activation of more enzymes, thus increasing its production of the product.