Summary
The end product of a pathway inhibits an early enzyme, preventing overproduction.
In depth
The final product binds to an allosteric site on the first committed enzyme and slows the pathway, saving energy and materials. When the product level drops, inhibition lifts.
It is a form of negative feedback at the molecular level.
In branched pathways each branch end-product may inhibit the first enzyme after the branch point as well as the common one, giving finely tuned control. The classic example is isoleucine inhibiting threonine deaminase at the start of its synthesis pathway.
Feedback prevents overproduction and saves energy; its failure leads to disease, for example when feedback on cholesterol synthesis is overridden. Positive feedback, in which a product boosts its own formation, is rarer but occurs in blood clotting and childbirth.
Example: the energy charge of a cell, high ATP, slows glycolysis, and low ATP speeds it up.
Frequently asked questions
What is Feedback Inhibition?
The end product of a pathway inhibits an early enzyme, preventing overproduction.
Which area of biology covers Feedback Inhibition, and how advanced is it?
Feedback Inhibition is one of the 51 topics in Biomolecules & Biochemistry. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Allosteric Regulation, Competitive Inhibition, Active Site.
Can you give an example of Feedback Inhibition?
CTP inhibits aspartate transcarbamoylase in pyrimidine synthesis.
What should I learn before Feedback Inhibition?
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Feedback Inhibition. Advanced topics assume the Intermediate vocabulary.
What topics are related to Feedback Inhibition?
The closest topics to Feedback Inhibition are Allosteric Regulation, Competitive Inhibition, Active Site, Noncompetitive Inhibition. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Feedback Inhibition?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Feedback Inhibition. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
How is Feedback Inhibition different from Allosteric Regulation?
Feedback Inhibition: The end product of a pathway inhibits an early enzyme, preventing overproduction. Allosteric Regulation: Binding of a molecule at a site other than the active site changes enzyme shape and activity. Read both side by side and note what each one explains.
How should I study Feedback Inhibition step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allosteric Regulation and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.