Key Area 1: Metabolic Pathways And Their Control

Question 1

What is metabolism?

Answer 1

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

Question 2

What type of reaction is a catabolic reaction?

Answer 2

A degredation reaction (breaks down molecules)

Question 3

What type of reaction is an anabolic reaction?

Answer 3

Synthesis reaction (builds up molecules)

Question 4

Which type of reaction produces energy?

Answer 4

Catabolic reaction

Question 5

What are the three ways a metabolic pathway can go?

Answer 5

Reversible, irreversible and alternative route

Question 6

What are the two main components of the plasma membrane?

Answer 6

Phospholipids and proteins

Question 7

What are the three main functions of proteins?

Answer 7

• protein pump (active transport)
• protein pore (diffusion)
• enzymes

Question 8

What are the two functions of membranes for metabolic reactions?

Answer 8

They provide a surface for the reaction to take place

They keep what’s needed for different reactions in their own compartments

Question 9

Why is it important for organelles to have a large surface area to volume ratio?

Answer 9

To allow substances to diffuse quickly in and out of cells

Question 10

What controls metabolic processes?

Answer 10

Signal molecules including hormones and enzymes

Question 11

What factors regulate a metabolic pathway?

Answer 11

Intra- and extra- cellular factors

Question 12

Induced fit: what are the roles of the active site?

Answer 12

To bind with the substrate

Orientating the substrate to get the substrate in the correct position

Question 13

Induced fit: what is the shape of the active site compared to the substrate?

Answer 13

They are similar but not exact so as the enzyme can bind with more than one substrate

Question 14

Induced fit: what is the activation energy of a reaction?

Answer 14

The energy needed to break chemical bonds

Enzymes lower the activation energy needed in a reaction

Question 15

Describe affinity to active sites in terms of the substrate and the product

Answer 15

The substrate has a high affinity to the active site

The product has a low affinity to the active site

Question 16

What happens to the rate of reaction as the substrate concentration increases?

Answer 16

As the substrate concentration increased the rate f reaction increases until it levels off

Question 17

What does reversibility mean when applied to metabolic reactions? And what does it depend on?

Answer 17

Reversibility means enzymes can catalyse reactions in both ways
It depends on the concentration of the substrate and the product

Question 18

What is a multi-enzyme complex?

Answer 18

Enzymes that have more than one active site ( eg DNA polymerase )

Question 19

What is enzyme induction?

Answer 19

The process of switching on a gene when it is needed by a cell

Question 20

Why is enzyme regulation needed in cells?

Answer 20

If more than the required amount of enzymes are made then it would be a waste

Question 21

What is non-competitive inhibition?

Answer 21

When the inhibitor joins to the allosteric site on the enzyme and changes the shape of the active site

Question 22

What is a competitive inhibitor?

Answer 22

When the inhibitor binds with the active site on the enzyme to block interaction with the substrate

Question 23

What is feedback inhibition?

Answer 23

When there is too much of the end product it acts as inhibitors to the enzyme back at the start of the metabolic pathway