5. Enzymes

Enzymes

Core

Define the term catalyst

Define the term Enzyme

Investigate and describe the effect of changes in 

temperature and pH on enzyme activity

Extended

Explain enzyme action in terms of the ‘lock 

and key’ model

Explain the effect of changes in temperature 

and pH on enzyme activity.

Describe the role of enzymes in the 

germination of seeds, and their uses in 

biological washing products and in the food 

industry (including pectinase and fruit juice)

Outline the use of microorganisms and 

fermenters to manufacture the antibiotic 

penicillin and enzymes for use in biological 

washing powders

Describe the role of the fungus Penicillium in 

the production of antibiotic penicillin

A catalyst is a substance which speeds up a chemical reaction, an enzyme is an example of one of these. Catalysts are also not changed by reactions.

An enzyme is a protein and biological catalyst which speeds up chemical reactions in the body, without them, reactions would take place far to slow for life to take place.

Enzymes have an optimum PH and Temperature to work in, any change to this could result in Enzymes being denatured which means that it has basically changed shape so much, that it's substrate can no longer fit into it. The optimum Temperature for enzymes is 37 degrees Celsius which also just happens to be our internal body temperature.

Extended

The lock and key method is fairly easy to understand (consult picture above right) In essence, an enzyme is like a lock and a certain substrate is that enzyme's matching key. The substrate (molecule being worked on) 

attaches itself to the enzyme's 

active site. This is now known as an enzyme - substrate complex, after a while the enzyme will change shape slightly and release products.

As temperature increases past an enzymes optimum working temperature the rate of reaction will slow down and eventually (if temperature keeps increasing) the enzyme will denature and will no longer fit any substrate.