LC BIOLOGY- Enzymes

Metabolism

the sum of all the chemical reactions in our bodies

Homeostasis

the maintenance of stable conditions in our bodies

Solar Energy

energy from the sun

Cellular Energy

the energy stored in the bonds of biomolecule

when the bonds are broken down, energy is released during respiration in the mitochondria

Catalyst

a substance that speeds up a reaction, without itself being used up in the reaction

Enzymes

proteins that speed up a reaction without being used up in the reaction

Features of Enzymes

• made of protein

• complex, 3D shape

• reactions are reversible

Substrate

the substance with which an enzyme reacts

Product

the substance(s) the enzyme forms

Anabolic Enzymes

form more complex compounds

Catabolic Enzymes

break down larger compounds

Amylase

a catabolic enzyme (produced by the salivary glands and pancreas) that converts starch into maltose

starch → maltose

DNA Ligase

an anabolic enzyme used in genetic engineering to join two pieces of DNA together

DNA Polymerase

an anabolic enzyme found in both plants and animals that forms and repairs DNA

Bioprocessing

the use of enzyme-controlled reactions to produce a product

Uses of Bioprocessing

used to produce cheeses, beers, vaccines, antibiotics, etc.

Bioreactor

a vessel or container in which living cells or their products are used to make a product

Batch Culture

• fixed amount of substrate is placed in a bioreactor

• reaction is allowed to proceed

• product collected at end of reaction

• bioreactor cleaned for next batch

Continuous Flow Culture

• substrate is continually infused into the bioreactor

• reaction proceeds and conditions within are strictly controlled using sensors

• product is continually collected

Immobilised Enzymes

enzymes that are attached, or fixed, to each other, or to an inert material

Methods of Immobilising Enzymes

enzymes may be:

• attached to each other

• attached to insoluble supports

• enclosed within a membrane or gel

Benefits of Immobilised Enzymes

• they may be reused

• the process is cheaper

• their efficiency is not reduced

Uses of Immobilised Enzymes

• produce fructose (sweetener) from glucose

• convert penicillin to different forms

• produce sweet-tasting sugars from lactose

Glucose Isomerase

converts glucose to fructose

Penicillin Acylase

produces new antibiotics from penicillin

Lactase

converts lactose to glucose and galactose

Active Site

the part of an enzyme that combines with the substrate

Enzyme Specificity

each enzyme will react with only one particular substrate

Induced Fit Model

1. the substrate causes the active site to change shape slightly

2. the enzyme and substrate form a temporary enzyme-substrate complex

3. the substrate is altered

4. the enzyme remains unchanged and the active site returns to its original shape

Denatured Enzyme

an enzyme which has lost its shape and can no longer carry out its function

Optimum pH

the pH value at which the enzyme works best

(pH 2 for pepsin, pH 6 for most other enzymes)

Optimum Temperature

(human enzymes work best at 37°C, while plant enzymes work best at 20-30°C)

Causes of Denaturation

• high temperatures

• pH values outside the enzyme’s optimum pH

• some chemicals or radiation

Effect of Heat Denaturation on Catalase

can be investigated by…

• boiling catalase

• testing if it will then form foam when it reacts with hydrogen peroxide

Effect of pH on Enzyme Activity

• mix blended celery (catalase), hydrogen peroxide, pH buffer and washing-up liquid

• note the volume of foam formed after 2 minutes at different pH values

Effect of Temperature on Enzyme Activity

• mix blended celery (catalase), hydrogen peroxide, pH buffer 9, and washing-up liquid

• note the value of froth formed after 2 minutes at different temperatures

Immobilisation of Sucrase

• mixing yeast solution with sodium alginate solution

• adding beads of the mixture to calcium chloride solution

• rinsing the hardened beads in a sieve

Application of Immobilised Enzyme

is shown by…

• adding sucrose solution to immobilised yeast (containing sucrase) in a separating funnel

• testing for the production of glucose