Name: how cells control product buildup
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 46 s
Channel: JoVE

In a regulatory process called feedback inhibition, the product of a reaction inhibits an enzyme at an earlier step in the metabolic pathway that produced it, thereby slowing, or shutting down, its own production.

The product does this by binding to a regulatory site on the enzyme, which is distinct from the active site that binds to the substrate. When the product binds to regulatory site, it causes a confirmational change in the enzyme that inhibits it from continuing to catalyze the reaction.

This activity prevents excessively high levels of the product from accumulating, and, once the level drops low enough, the product no longer inhibits the enzyme, and production can continue as usual.

feedback inhibition

Feedback Inhibition

Biochemical reactions are occurring constantly in cells, converting starting substances to different products, usually with the help of enzymes that speed the reactions. Without enzymes, it would take far too long for most reactions to occur to be useful to the cell!

Since enzymes help control the rate of reactions, their activity is regulated so that appropriate amounts of starting materials, intermediate metabolites, and products are maintained in the cell. Excessive build-up or depletion of substances can have disastrous consequences on the health of the cell and organism.

In a regulatory process called feedback inhibition, the product of a reaction inhibits an enzyme at an earlier step in the metabolic pathway that produced it. The product binds to a regulatory site on the enzyme, which is distinct from the active site that binds to the substrate, thereby slowing or shutting down its own production. When the product binds to the regulatory site, it causes a conformational change in the enzyme that prevents it from binding to the substrate and continuing to catalyze the reaction.

This prevents excessively high levels of the product from accumulating in the cell. When its level drops low enough, the product no longer inhibits the enzyme, and the reaction can proceed as usual.

Biochemical reactions are occurring constantly in cells, converting starting substances to different products, usually with the help of enzymes that speed ...

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KEY TERMS AND CONCEPTS

how cells control product buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products.

If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important control process is feedback inhibition. In this process, the final product of a reaction slows an enzyme from an earlier step in the same pathway.

The product binds to a regulatory site on the enzyme. This site is different from the active site, which is where the substrate normally binds. Binding at the regulatory site changes the enzyme’s shape. That conformational change prevents the enzyme from binding the substrate and keeps the reaction from continuing.

Feedback inhibition helps stop too much product from accumulating in the cell. When product levels fall, the product no longer inhibits the enzyme. The pathway can then start again and continue producing the molecule as needed.

How Cells Control Product Buildup

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key terms and concepts

Learn how feedback inhibition lets cells regulate enzymes, stop product buildup, and keep metabolic reactions balanced in high school biology.

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How Cells Control Product Buildup

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