Key Area 2.1 Metabolic pathways and their control

Question 1

what is metabolism?

Answer 1

Metabolism is the biochemical process that life depends on.

Question 2

What are the 2 types of metabolic pathways?

Answer 2

Catabolic and anabolic.

Question 3

What is a catabolic reaction?

Answer 3

Catabolic reactions breakdown bigger molecules into smaller molecules and release energy.

Question 4

What is an anabolic reaction?

Answer 4

Anabolic reactions build up large molecules from small molecules and require energy.

Question 5

What are the 3 types of steps in metabolic pathways?

Answer 5

Reversible, irreversible, and alternative routes.

Question 6

What is an alternative route?

Answer 6

When substrates are plentiful or in short supply steps in the pathways can be bypassed. This conserves energy.

Question 7

What are the 3 types of protein found in the cell membrane?

Answer 7

Enzymes, pumps, and pores.

Question 8

What is a pore?

Answer 8

Larger molecules depend on channel forming proteins to form pores to allow movement across the membrane.

Question 9

What is a pump?

Answer 9

Protein pumps allows active transport to occur as they recognise specific molecules and transfer them across the membrane.

Question 10

What is an enzyme?

Answer 10

Enzymes are biological catalysts.

Question 11

What do enzymes do to the activation energy?

Answer 11

Lower it.

Question 12

What are enzymes said to be?

Answer 12

Specific.

Question 13

What does it mean that the enzymes are specific?

Answer 13

The enzyme only works with one substrate.

Question 14

Do the enzyme and substrate have a high or low affinity for each other?

Answer 14

High.

Question 15

What does it mean that enzyme has an induced fit?

Answer 15

The active site is slightly flexible and slightly alters its shape when the substrate enters.

Question 16

Do the end products have a high or low affinity with the active site?

Answer 16

Low.

Question 17

What factors affect enzyme activity?

Answer 17

Temperature
pH
Supply of substrate
Inhibitors.

Question 18

How does increasing the substrate concentration affect enzyme activity?

Answer 18

As the substrate concentration increases the enzyme activity increases, it then remains constant.

Question 19

Why does the enzyme activity remain constant even if the substrate concentration continues to increase?

Answer 19

All the enzymes active sties are occupied.

Question 20

What is it called when all the enzymes active sites have been occupied?

Answer 20

Saturation point.

Question 21

What are the 3 types of inhibitors?

Answer 21

Competitive
Non-competitive
Feedback.

Question 22

What does a competitive inhibitor do?

Answer 22

Competitive inhibitors have a similar structure to the substrate and so can block the active site by going into the active site instead of the substrate. This decreases the rate of chemical reactions.

Question 23

What does increasing the concentration of the substrate do to competitive inhibition?

Answer 23

Reverses them.

Question 24

What do non-competitive inhibitors do?

Answer 24

Non-competitive inhibitors attach to a non-active site on an enzyme. This permanently alters the shape of the enzyme, and therefore its active site, and so the substrate molecule no longer can combine with the enzyme.

Question 25

What type of inhibition is non-competitive inhibition?

Answer 25

Irreversible.

Question 26

What is feedback inhibition?

Answer 26

Feedback inhibition is when the end product of a reaction inhibits an enzyme earlier on in the pathway that produced it.

Question 27

What can feedback inhibition prevent?

Answer 27

Wasteful conversion and accumulation.