The Effect Of Temperature On Anaerobic Respiration In Yeast

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GCSE Biology Coursework

The Effect Of Temperature On Anaerobic Respiration In Yeast

Enzymes

Enzymes are the tools of life. They do almost everything in a cell. Virtually every one of life’s chemical reactions is driven by some enzyme. Enzymes are organic catalysts that work like a starter on a car. With a small input of energy from the starter, a car can run on its own energy all day. They don’t get not used up or changed when they “jumpstart” another molecule. They can perform the same task over and over working very fast. They can carry out their task thousands of times per second. Each enzyme has its own unique structural shape that allows it to bind to or “unlock” certain other molecules called substrates. When the correct “lock” and “key” come together, a chemical bond is formed.


Lock and Key Theory

The lock and key structure is a theory on why enzymes catalyse reactions. This theory states that all enzymes and substrates (the object which the enzyme act on) have specified structures (active site) and chemical properties. The substrate fits into the enzyme's active site, and they react. The substrate is broken down, and then the enzyme can act on the next substrate. This can be done as quickly as 32 million particles per second. This means that, like only a certain and correctly sized and shaped key can fit into a certain lock, only a certain substrate (key) can fit into a certain active site (or key hole) in the enzyme(lock). This is displayed clearly in the diagram below.

Kinetic Theory

This is a theory that suggests as temperature increases, the molecules move faster, due to increased kinetic energy. This causes the enzyme and substrate molecules to meet more often meaning the rate at which the product is formed will increase. However, as the temperature continues to increase the hydrogen and ionic bonds, which hold the enzyme in shape, break and the active site will no longer accommodate the substrate. When this happens we say the enzyme has denatured, this cannot be reversed.

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                                                                                                    Preliminary Experiment

Aim: To establish a basic relationship between temperature and respiration rate in yeast.

Before completing the final experiment I decided to do a preliminary experiment in order to get some basic results and in order to get a good understanding of what I was doing ...

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