Feedback inhibition
The end product of a pathway switches off an early enzyme in that pathway. This stops the cell making more than it needs.
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Analogy
A thermostat that turns the heater off when the room is warm enough.
In practice
When a cell has plenty of isoleucine, the amino acid shuts down the first enzyme in its own production line.
Practice
Flashcards
- What is feedback inhibition?The end product of a pathway blocks an early enzyme, so the cell stops making too much.
Questions people ask
What is allosteric regulation?
Allosteric regulation happens when a molecule binds an enzyme at a site away from the active site and changes the enzyme's shape. An activator makes the active site work better. An inhibitor makes it work worse. Many feedback loops use this method, because it responds quickly and is reversible.
Why is feedback inhibition more efficient than switching genes off?
It acts within seconds, because it works on enzymes that are already there. Changing gene activity takes much longer, since new proteins have to be made or old ones broken down. Cells use both: fast feedback for quick adjustments and gene control for longer-term change.