Why does feedback inhibition occur in cells

Wiki User. It is a simple and energy efficient way to regulate the production of substances in the cell where enzymes in a metabolic pathway are inhibited by their downstream products. This slow's the flux through a metabolic pathway and maintains homoeostasis preventing a build up of the product which if left unchecked could build up to toxic levels as the enzyme would continue to create the substance as long as enough reagents were present regardless of the damage it could cause to the cell or the organism.

In feedback inhibition, the allosteric effect lowers the affinity of the enzyme for its substrate. The feeling of fullness and hunger are examples of the negative feedback inhibition.

It feeds part of a systems output, inverted, into the system's input. The "negative feedback inhibition" controls the endocrine system.

One common example of feedback inhibition would be hexokinase being inhibited by its product glucosephosphate in the glycolytic pathway. Mark S. The steroid hormones produced by the adrenal cortex exhibit feedback inhibition on ACTH production, therefore a low concentration of corticosteroids as seen in Addisons disease will not exhibit this feedback inhibition. Without this inhibition, ACTH levels are not regulated and therefore rise. G1 checkpoint. Most of the mechanisms in our body are regulated by negative feedback inhibition.

In this type of process final product shuts off the original stimulus. Blood clotting in our body is regulated by positive feedback inhibition. In this type of process response leads to an even greater response. In this type of process, the end product shuts off or reduces the intensity of the original stimulus.

Production of certain hormones when mother is giving birth to a child is regulated by positive feedback inhibition. In this type of process, response leads to an even greater response. Feedback inhibition.

Negative feedback inhibition. Contact Inhibition. Excitation and Inhibition occur in the neurons. Excitation is when a neuron becomes depolarized and fires an action potential. This occurs because the product itself as able to act as an enzyme inhibitor at certain concentrations, multiple reactions "upstream" of where it is formed. When a molecule, which you can think of as C, feeds back two steps in a reaction to act as an allosteric inhibitor of the production of B from molecule A, it is because too much C has built up in the cell.

With less A being converted to B thanks to the allosteric inhibition by C, less B is made into C, and this occurs until enough C is consumed to draw it away from the A-to-B enzyme to get the reactions going again.

The synthesis of ATP, the universal fuel currency of living cells, is controlled by feedback inhibition. ATP comes from cellular respiration, and ATP acts as an allosteric inhibitor of the enzymes at various steps in the cellular respiration process.

Although ATP is a fuel molecule and thus indispensable, it is short-lived and spontaneously reverts to ADP when found in high concentrations.

This means that an excess of ATP would only go to waste if the cell went to the trouble of synthesizing greater amounts than it does thanks to feedback inhibition.

Kevin Beck holds a bachelor's degree in physics with minors in math and chemistry from the University of Vermont. Formerly with ScienceBlogs. More about Kevin and links to his professional work can be found at www. When it is time to order an enzyme to stop, the cell has a number of ways to do this.

Unless otherwise noted, images on this page are licensed under CC-BY 4. Text adapted from: OpenStax , Concepts of Biology.

OpenStax CNX. Skip to content Molecules can regulate enzyme function in many ways. Figure 11 Metabolic pathways are a series of reactions catalyzed by multiple enzymes. Feedback inhibition, where the end product of the pathway inhibits an upstream process, is an important regulatory mechanism in cells. Previous: Enzymes.