Unit 2: Chapter 3 - Enzymes

Question 1

Proteins, Catalysts and Enzymes

Answer 1

Proteins carry out lots of functions:

• Contract muscles
• Structural components
• Anti-bodies
• Biological catalysts
• Hormones

ENZYMES

Enzymes also know as biological catalysts are important for speeding up reactions.

These are large protein molecules (long amino acid chains). Enzymes have specific active site shape so that substrates can bind together.

Enzymes help by:

• Building large molecules from lots of smaller ones.
• Changing one molecule into another
• Breaking down large molecules into smaller ones.

Enzymes do not change reactions. They speed them up.

There are specific enzymes for specific reactions.

Question 2

Factors Affecting Enzyme Action

Answer 2

There are two factors that affect the way an enzyme works:

• pH levels
• Temperature

Enzymes denature is pH levels are too high. These usually happens around the pH of 1-2 and lower.
However, some enzymes are suited in that particular condition of the stomach. Pepsin is found in stomach acid which is its optimum pH.

If the pH is too low, the enzymes also stop working.

The enzymes slow the rate of reaction is body temperature is cold.

If it is too high, it will simply denature which can be life-threatening.

Question 3

Enzymes in Digestion

Answer 3

There are 3 places where enzymes are produced:

• Salivary gland
• Pancreas
• Small Intestine

Carbohydrates are digested by carbohydrases such as amylase. This is produced in the SALIVARY GLANDS, PANCREAS and SMALL INTESTINE.

Proteins are digested by proteases such as pepsin that takes place in STOMACH and SMALL INTESTINES. The end product is AMINO ACIDS.

Lipids are digested by lipases into FATTY ACIDS and GLYCEROL. Proteases are formed in the PANCREAS and SMALL INTESTINE.

Question 4

Speeding up Digestion

Answer 4

pH

To digest effectively, an enzyme must work at is optimum pH.
Pepsin is an enzyme that only works in an acidic pH in the stomach.

Stomach acid is then NEUTRALISED by the acidic bile in the gall bladder that connects to the pancreas. This provides ideal conditions for enzymes within the small intestine.

SURFACE AREA

The bile breaks down fats to allow the maximum surface are for enzymes to digest. This is not a problem for carbs and proteins.
It also emulsifies fats in the food into smaller droplets for a much bigger surface area.

Question 5

Making Use of Enzymes

Answer 5

Some examples of enzymes used in everyday life are:

• Biological Detergents
• Baby Food
• Fructose syrup

BIOLOGICAL DETERGENTS
- Biological detergents remove stains with lipases and proteases to break down proteins and fats. These are good to use because they require less electricity to heat the water and work at lower temperatures. However, if the water is too hot, enzymes denature.

BABY FOOD

• Proteases are used to make baby food. These enzymes pre-digest the food so that a baby’s digestive system can cope with it. This makes it easier for babies to get the essential amino acids they need.
• Carbohydrases are also used in a variety of foods such as sugar syrup.

FRUCTOSE SYRUP
- Isomerase is used to digest glucose syrup into fructose syrup. Same amount of calories however fructose syrup is sweeter than glucose syrup.

+ Vs -

• Expensive equipment
• Requires lots of energy

+ Can be produced in catalase reactions and reduce energy costs.
+ Costs money to control conditions so enzymes don’t denature.