Investigating the “lock+key” hypothesis

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Investigating the "lock+key" hypothesis

An enzyme is a type of protein found in all living cells. Enzymes act as biological catalysts, allowing all the chemical reactions of metabolism to take place, regulating the speed at which they progress, and providing a means of controlling individual biochemical pathways. Enzymes have a precise 3-dimensional shape.

According to the 'lock-and-key' hypothesis, the substances upon which an enzyme acts (which are known as substrates) fit into a special slot in the enzyme molecule - the active site. A chemical reaction takes place at this site and the products are released, leaving the enzyme unchanged. This can be repeated 100,000 times per second. Enzymes are usually only effective for one substrate because each needs a different shaped active site.

They function best in particular conditions of temperature and acidity (pH), and their action can be slowed or stopped by inhibitors. Many enzymes need a coenzyme in order to function. The human body contains at least 1,000 different enzymes. Amylase is an enzyme that reacts with starch converting it into glucose molecules.

Aim

To find out how enzyme concentration affects the rate of an enzyme controlled reaction

Hypothesis

I believe that the effect of increasing the concentration of the enzyme will increase the speed with which the enzyme-controlled reaction takes place.
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This prediction is correct according to the "Lock And Key" hypothesis explained earlier. There will be more enzyme molecules available in a given volume of amylase solution. This way more amylase molecules will be catalysed at the same time because each needs an enzyme molecule to catalyse it. If there many more starch molecules than amylase ones many of the starch molecules will be left floating around until an enzyme's active site is freed.

The more enzyme molecules there are the faster the reaction. But past a certain enzyme concentration the rate will no longer change because ...

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