B3 - Enzymes and Cell Reactions

Information about enzymes, required for your OCR biology exam.

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Cell Reactions

Enzymes control cell reactions such as respiration, photosynthesis, and protein synthesis.

Cells have thousands of different chemical reactions that occur in them all the time, so enzymes are important.

Cell reactions need to be carefully controlled.

This is because the right amounts of substances need to be made, or the organism won't function properly.

Too little substances produced, and it will die.

Too many substances produced, and it will die.

It needs to be just right.

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Temperatures

Enzymes work best at a certain temperature.

This is called its optimum temperature.

Enzymes work better the higher the temperature is, but as soon as it passes the optimum temperature, they stop working entirely.

If the temperature is too low, then the enzymes work really slowly, or not at all.

This means the chemical reaction is slow, or doesn't occur.

This is bad.

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Biological Catalysts

Enzymes act as biological catalysts.

This is because they speed up a reaction.

Anything that speeds up a reaction AND isn't used up or damaged in the process is labelled a catalyst.

If it is used up or damaged, then it is just temporarily useful.

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Benefits of Enzymes

High temperatures are beneficial for bodily reactions, but the temp. can only go so high before it becomes harmful to the body.

Enzymes are useful because they reduce the need for such high temperatures.

This is the only use our bodies have for enzymes.

Every different biological reaction has its own enzyme, which is designed especially for it.

Enzymes are coded for by a different gene for each one.

All enzymes have a different shape. This is so that it can do the job required.

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