Biological molecules

Question 1

What are the 3 common types of molecules in our body?

Answer 1

• Carbohydrates
• Proteins
• Lipids

Question 2

What are proteins, carbohydrates and lipids classified as? Why?

Answer 2

They are all organic molecules as they contain carbon

Question 3

What elements are carbhoydrates made of?

Answer 3

Carbon, Hydrogen and Oxygen

Question 4

What is the chemical formula of glucose?

Answer 4

C6H12O6

Question 5

What type of sugar is glucose?

Answer 5

A monosaccharide (simple sugar)

Question 6

What are disaccharides?

Answer 6

2 monosaccharides joined together. E.g. maltose = glucose + glucose
E.g. sucrose = glucose + fructose

Question 7

What are polysaccharides?

Answer 7

• Composed of many monosaccharides joined together
• Insoluble so great for storage

E.g. starch

Question 8

What are proteins made of?

Answer 8

Chains of amino acids

Question 9

What is so special about the structure of the amino acids in a protein?

Answer 9

The structure, order and shape of the amino acid chain will define what protein is made. A small change in any of these 3 factors will result in a completely new protein being formed

Question 10

How many different amino acids are there?

Answer 10

20

Question 11

What is an enzyme?

Answer 11

A biological catalyst which speeds up the rate of chemical reactions in our body without being used up or changed.

Question 12

Where are enzymes made?

Answer 12

In living cells

Question 13

Why are enzymes important?

Answer 13

They ensure all metabolic reactions in our body maintain their rate

Question 14

Explain the lock and key hypothesis

Answer 14

• The shape of the active site and the substrate are complimentary
• Enzymes are specific to 1 substrate
• So enzymes usually catalyse only 1 type of reaction

Question 15

Explain the effect of temperature on enzyme activity

Answer 15

• As temperature increases, the KE of the particles will increase
• Therefore, there will be more frequent successful collisions between the enzymes and the substrates leading to higher enzyme activity
• Once the temperature exceeds the enzyme’s optimum temperature, the enzyme will become denatured

Question 16

What does it mean if an enzyme is denatured?

Answer 16

Its active site is deformed due to extreme temperatures or pH so it can no longer catalyse reactions as the substrate can no longer fit in the active site

Question 17

Explain the effect of pH on enzyme activity

Answer 17

• Most enzymes have an optimum pH of 7
• Enzymes in acidic environments (like the stomach) have lower optimum pHs (2)
• Enzymes in alkaline environments (like the duodenum) have higher optimum pHs (8 or 9)
• Moving too far away from the optimum pH of an enzyme will cause it to denature