2.1 Metabolic Pathways

Question 1

metabolic pathways

Answer 1

integrated and controlled pathways of enzyme-catalysed reactions within a cell

Question 2

metabolic pathways can have (3)

Answer 2

• reversible steps
• irreversible steps
• alternative routes

Question 3

anabolic reactions

Answer 3

• build up large molecules from small molecules
• require energy

Question 4

catabolic reactions

Answer 4

• break down large molecules into small molecules
• release energy

Question 5

what are embedded in membranes? (3)

Answer 5

• protein pores
• pumps
• enzymes

Question 6

metabolic pathways are controlled by (2)

Answer 6

• the presence/absence of particular enzymes
• the regulation of the rate of reaction of key enzymes

Question 7

adding enzymes to a reaction does what?

Answer 7

lowers the activation energy needed for it to proceed

Question 8

the active site of an enzyme is…

Answer 8

flexible

Question 9

induced fit

Answer 9

when the active site of an enzyme changes place to fit closely around the substrate

Question 10

induced fit ensures… (2)

Answer 10

• the active site comes into close contact with the substrate
• the chance of a reaction occurring increases

Question 11

affinity

Answer 11

the tendency of a molecule to bind to an enzyme

Question 12

substrates have a high affinity for what?

Answer 12

the active site of an enzyme

Question 13

after a reaction, what happens to the affinity of the products for the active site?

Answer 13

it lowers, so they seperate

Question 14

inhibitor

Answer 14

a substance which decreases the rate of an enzyme controlled reaction

Question 15

competitive inhibitors (3)

Answer 15

• bind at the active site
• prevents the substrate from binding
• can be reversed by increasing substrate concentration

Question 16

non-competitive inhibitors (3)

Answer 16

• bind away from the active site
• change the shape of the active site, which prevents the substrate from binding
• cannot be reversed by increasing substrate concentration

Question 17

feedback inhibitors (3)

Answer 17

• occurs when the end product of a metabolic pathway reaches a high concentration
• some of the end product binds to the enzyme
• this prevents further synthesis of the end product