The Effect of Temperature on the Rate of Respiration in Yeast

The Effect of Temperature on the Rate of Respiration in Yeast

I have chosen to investigate the affect temperature has on the rate of

respiration in yeast. I will use an experiment to determine whether

the yeast's rate of respiration will be quicker, slower or if it does

not change when the temperature is varied.

Scientific Knowledge

The first thing to say about enzymes is that they are proteins and

they are found in all types of organisms from humans to viruses. They

function in the body as catalysts. In other words they speed up the

rate of chemical reactions in the body. Enzymes actually accelerate

chemical reactions by a factor of about 1 million. Enzymes are organic

catalysts. Without enzymes the metabolism of an organism would be too

slow for the organism to survive. The word enzyme actually means "in

yeast" as they were first discovered in these micro-organisms.

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Enzymes are found inside and outside cells. Enzymes found outside

cells are for example, those that control metabolism while enzymes

found inside cells for example, gut digestive juices and the enzymes

secreted by bacteria, which digest their food outside the body then

reabsorb the products. Enzymes work on particular organic chemicals,

these are called substrates. So food is the substrate of digestive

enzymes.

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The lock and key hypothesis attempts to explain how enzymes are

specific to particular substrates and how they may work. In this

hypothesis the enzyme is the lock and the substrate(s) is the key.

Enzyme molecules have a particular shape like a lock and only a

particular substrate (key) can fit into that lock. The part of the

enzyme that binds the substrate is called the "active site". Just like

other catalysts, after the enzyme has been involved in the reaction it