5: enzymes

Question 1

what is a biological catalyst?

Answer 1

substance that speeds up chemical reactions and remains unchanged by the reaction

Question 2

what are enzymes?

Answer 2

proteins functioning as biological catalysts that are involved in all metabolic reactions

Question 3

what are the two types of metabolic reactions?

Answer 3

• anabolic
• catabolic

Question 4

explain anabolic reactions

Answer 4

the synthesis of molecules through condensation

Question 5

explain catabolic reactions

Answer 5

the breaking down of molecules through hydrolysis

Question 6

what is an enzyme-substrate complex?

Answer 6

the temporary complex formed when an enzyme binds to its substrate molecule

Question 7

list down the properties of an enzyme [5]

Answer 7

1. biological catalyst
2. coded by DNA
3. most are globular proteins
4. lowers the activation energy
5. highly specific

Question 8

intracellular enzymes

Answer 8

enzymes inside a cell

Question 9

extracellular enzymes

Answer 9

enzymes outside a cell

Question 10

what is a metabolic pathway?

Answer 10

a series of connected chemical reactions that feed one another

Question 11

what do intracellular enzymes do?

Answer 11

they catalyse the reactions that occur in metabolic pathways

Question 12

what do extracellular enzymes do?

Answer 12

enzymes that work outside a cell; they have been secreted by a cell

Question 13

explain the mechanism of an enzyme

Answer 13

1. enzyme binds a substrate in the active site
2. enzyme-substrate complex forms
3. substrate reacts to form a product
4. product is released

Question 14

why is it that only certain substrates can fit with certain enzymes?

Answer 14

because the active site of an enzyme has a specific shape that only the intended substrate can fit into

Question 15

what is activation energy?

Answer 15

the minimum amount of extra energy needed for a reacting molecule to get converted into a product

Question 16

what does the rate of an enzyme catalysed reaction depend on?

Answer 16

• amount of enzymes
• speed of which the enzyme can convert a substrate into a product, release it, and then bind to another substrate

Question 17

what are the two ways of measuring an enzyme reaction?

Answer 17

1. disappearance of substrate during a period of time
2. product formed during a period of time