CB1E/F/G Enzymes

Question 1

What is an enzyme

Answer 1

A biological catalyst that controls reactions in the body

Question 2

How can you make a reaction happen more quickly

Answer 2

By raising the temperature

Question 3

What do enzymes do in the body

Answer 3

They enable cellular reactions to take place at lower temperatures

Question 4

What is the substrate

Answer 4

The molecule changed in the reaction

Question 5

What is the active site of an enzyme

Answer 5

The region of an enzyme which a substrate molecule binds onto and catalyses

Question 6

Why are enzymes described as having ‘high specificity’ for their substrate

Answer 6

Because only enzymes with a specific complementary shape can fit into an enzymes active site

Question 7

Describe the ‘lock and key’ model

Answer 7

Substrate collides with enzymes active sight
Enzyme binds
Substrate converted to products
Products released from the active sight are now free to bind to another substrate

Question 8

What three factors affect the rate of an enzyme reaction

Answer 8

Temperature
pH
Substrate concentration

Question 9

How does increasing temperature affect the rate of an enzyme reaction

Answer 9

Temp increases so molecules have more KE
Movement of molecules increase
Collision increases
Enzyme substrate complexes form
Rate of reaction increases

Question 10

Explain how increasing the temperature above the optimum affects the rate of an enzyme controlled reaction

Answer 10

Temperature increases above the optimum
Increased vibrations break bonds in enzyme’s structure
Active sight changes shape, enzyme is denatured
No more enzyme-substrate complexes can form
Rate of reaction decreases

Question 11

Graph to show effect of increasing temperature on the rate of an enzyme-catalysed reaction

Question 12

Explain how pH affects the rate of an enzyme

Answer 12

Enzymes have an optimum pH
pH shifts from the optimum
Bonds in the enzyme’s structure are altered
Active sight changes shape, enzyme is denatured
Rate of reaction decreases

Question 13

Draw a graph to show the effect of increasing pH on rate of enzyme catalysed reaction

Question 14

Explain how the substrate-concentration affects the rate of an enzyme reaction

Answer 14

Substrate concentration increases
Number of substrate molecules in the same volume increases
Probability of a successful collision increases
More enzyme-substrate complexes form
Rate of reaction increases
Once all active sites become full, the rate of reaction plateaus

Question 15

Draw a graph to show the effect of increasing substrate concentration on the rate of an enzyme-catalysed reaction

Question 16

Why must large organic molecules be broken down into smaller, simpler molecules in the body

Answer 16

Large molecules are broken down into smaller molecules for absorption into the bloodstream

Question 17

Give an example of the breakdown of large molecules in plants

Answer 17

Starch is broken down by enzymes into simple sugars which are respired to release energy

Question 18

What types of molecules are proteins and carbohydrates

Answer 18

Polymers

Question 19

What are the monomers of carbohydrates

Answer 19

Simple sugars

Question 20

Which group of enzymes catalyses the breakdown of carbohydrates

Answer 20

Carbohydrases

Question 21

Which type of carbohydrate catalyses the breakdown of starch

Answer 21

Amylase

Question 22

What are the monomers of proteins

Answer 22

Amino Acids

Question 23

Which type of enzyme catalyses the breakdown of proteins

Answer 23

Proteases

Question 24

What is the function of lipases

Answer 24

Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol

Question 25

Why are small molecules synthesised into larger organic molecules in the body

Answer 25

Large molecules are used for storage or are used to build structures

Question 26

Which enzyme catalyses the formation of glycogen from glucose

Answer 26

Glycogen synthase