1. The biological catalyst
Enzymes
The biological catalyst

2. What is an Enzyme?
Enzymes are catalysts that are produced by living organisms.
A catalyst speeds up chemical reactions without being changed by the reaction itself.
Enzymes are globular
proteins which act as
catalysts in chemical
reactions in living
things. 

3. Chemical processes would occur at a rate that is too slow for living organisms if enzymes were not involved.
Cells can control their metabolism by controlling the enzymes they produce.
During these chemical
reactions, one or more
substrates are catalysed
by an enzyme into a
product.

4. Enzymes are composed of long chains of amino acids that have folded into a very specific three-dimensional shape which contains an active site.
An active site is a region on the surface of an enzyme to which substrates will bind and which catalyses a chemical reaction involving the substrate.

5. Enzyme-Substrate Specificity
The active site of each enzyme has a very specific and intricate shape and it also has distinct chemical properties that match those of its substrate.
Not only does the
substrate molecule
fit the shape of the
active site but it is
also chemically
attracted to it.

6. This is known as enzyme-substrate specificity
This is known as enzyme-substrate specificity. The enzyme and substrate fit together like a key fits a specific lock. The enzyme is the lock and the substrate is the key.

7. Effects on Enzyme Activity
Enzymes can be affected by three different factors in their environment.
A change in these factors can affect the rate at which the enzyme will work or they can render it ineffective.
Enzymes must have the right conditions they need in order to work effectively.
Enzyme activity is affected by temperature, pH, and the concentration of the substrate.

8. Temperature
Enzyme activity will increase as temperature increases (often doubles with every 10˚C rise).
At a higher temperature more collisions occur between the substrate and the enzymes due to faster movement of molecules.
However, at high temperatures enzymes are denatured and stop working.
High heat causes vibrations inside the enzymes which break bonds needed to maintain the structure of the enzyme.

10. PH
As pH levels increase or decrease from the optimum level for each specific enzyme, the activity level is reduced.
Both acids and alkalis can denature enzymes. A pH of 7 is optimum for most enzymes.

11. Substrate Concentration
Enzyme activity is directly proportional to substrate concentration at low concentration levels.
As the concentration of the substrate rises, the enzyme activity increases because random collisions of substrate molecules and enzymes increases as the concentration of the substrate increases.  
At high substrate concentrations, all the active sites of the enzymes will be occupied so raising the concentration level will no longer have an effect.

13. Denaturation
Denaturation is changing the structure of an enzyme (protein) that results in the loss (usually permanent) of its biological properties.
This means it can no longer carry out its function.
Denaturation occurs
as a result of a
change in temperature
or pH.

14. Lactose free milk Enzymes are a very important part of biotechnology,
which is the use of
organisms or parts
of organisms to
produce things or
carry out useful
processes.

15. Lactose is a dissacharide found in milk.
The enzyme lactase is used to break it down into glucose and galactose (two monosaccharides).
Under normal circumstances the human body produces enough lactase to break down any lactose consumed in the diet.

16. Biotechnology companies culture a particular species of yeast known as Kluyveromyces lactis which grows naturally in milk.
These yeast produce lactase which the companies extract and purify to sell to food manufacturing companies.

17. Lactase can be added to milk to break down lactose into glucose and galactose.
This is very helpful to people who are lactose intolerant.
People who are lactose intolerant do not produce enough lactase to break down the lactose found in milk and milk products.
By adding lactase to milk, the lactose is broken down before it is consumed therefore making the milk product lactose-reduced and it can be consumed by an individual with lactose intolerance.