B4: Enzymes

1) Describe why Enzymes are important in all living organisms

Enzymes are proteins that act as biological catalysts.
They are necessary to all living organisms as they maintain the reaction speed of all metabolic reactions at a rate that can sustain life.

2) Explain enzyme action

Each enzymes contain an active site, which is a sequence of amino acids with a specific 3-D shape.
This shape is complementary to a specific substrate.
The substrate enters the active site to form an enzyme-substrate complex.
The substrate is broken down and the product is released.
The enzyme can then bind to another substrate molecule.

source: prenhall

Enzyme actions can be for:

3) Explain the Specificity of enzymes

The enzyme has a shape called the active site, which exactly fits the substances on which it acts.
The shape of the active site of the enzyme molecule and the substrate molecules are complementary.

4) Explain the Effect of changes in Temperature on enzymes activities

Enzymes have an optimum temperature they work best at, giving the fastest reaction, ≈ 37°C in animals.
As the temperature increases, molecules have more kinetic energy, so move faster, more successful collisions occur, and more enzyme-substrate complexes can form.
At high temperature, enzyme molecules vibrate too vigorously and enzyme become denatured; the active site loses its shape and will no longer bind with a substrate. This decreases the rate of reaction as no enzyme-substrate complexes can form.
When low temperature, there is not enough kinetic energy for the reaction so it reacts too slowly.

source: creative-enzymes

5) Explain the Effect of changes in pH on enzymes activities

Enzymes have an optimum pH that they work best at, some enzymes work best in an acid and others in an alkaline.
If the pH moves too far away from the optimum, it can cause the shape of the active site to change, and the enzyme become denatured. This decreases the rate of reaction as no enzyme-substrate complexes can form.

source: creative-enzymes

6) Enzymes and their Uses

Seeds to germinate:

Biological washing powders:

Enzymes are added to washing powders to help remove stains for example: lipase for lipids from fatty foods and greasy fingerprints.
Protease for proteins from blood stains.

Food industry:

Isomerase converts glucose to fructose which is sweeter, so less is needed to give a sweet taste.
Pectinase helps break down cell walls in fruit juice production so it increases yield, lowers viscosity and reduces cloudiness.

Summary

You should know: