Metabolic Pathways (1.6)

Question 1

What is cell metabolism (1)

Answer 1

The collective term for all the chemical reactions that take place in a living cell.

Question 2

What is meant by Anabolic reactions (1)

Answer 2

Anabolic reactions BUILD UP large molecules from small molecules and REQUIRE ATP. E.g. ATP required to build up amino acids to form a protein.

Question 3

What is meant by Catabolic reactions (1)

Answer 3

Catabolic reactions BREAK DOWN large molecules into smaller molecules and RELEASE ATP.

Question 4

What are examples of degradation reactions in the human body (1)

Answer 4

HPCOW: Hydrogen peroxide + catalyse = oxygen + water.

Question 5

What are metabolic pathways (1)

Answer 5

A metabolic pathway is a series of stepwise chemical reactions that are controlled by enzymes.

Question 6

What are the two types of metabolic pathways (2)

Answer 6

Anabolic and Catabolic.

Question 7

In a metabolic pathway, what controls each step (1)

Answer 7

Enzymes.

Question 8

What are enzymes (1)

Answer 8

Enzymes are biological catalysts.

Question 9

What is a catalyst (1)

Answer 9

A Catalyst is a substance that speeds up the rate of reaction by lowering the ATP needed to make the reaction proceeds.

Question 10

Why do enzymes speed up (1)

Answer 10

Biological reactions causes this.

Question 11

What is the energy needed to break the chemical bonds in a chemical reaction called (1)

Answer 11

Activation energy.

Question 12

What is induced fit (1)

Answer 12

Induced fit is when the active site can change shape slightly when it comes in contact with a substrate molecule for a better fit.

Question 13

What does affinity mean (1)

Answer 13

An attraction for something.

Question 14

If a substrate has a high affinity for the active site, what does the active site do (1)

Answer 14

The active site holds the reactants together together in an induced fit. This acts to weaken the chemical bonds in the reactants. This allows the reaction to take place.

Question 15

Once the reaction has taken place what do the products have and what does this cause to happen(1)

Answer 15

The products have a low affinity for the active site and are therefore released.

Question 16

What is an inhibitor (1)

Answer 16

Is a substance that reduces the rate if an enzyme reaction.

Question 17

What are the two types of enzyme inhibitor (2)

Answer 17

Competitive and non-competitive.

Question 18

What does a competitive inhibitor do / What does a non-competitive inhibitor do (2)

Answer 18

inhibitors compete for the active site with the substrate; Inhibitors don’t compete for the active site

Question 19

How does feedback inhibition do and how does this work?

Answer 19

Feedback Inhibition occurs when the end product in the metabolic in the metabolic pathway reaches a critical concentration. The end product inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end product. This regulates the whole pathway.

Question 20

Give an account of enzyme action (5)

Answer 20

Substrate has a high affinity for the active site; induced fit; enzymes lower the activation energy; products have a low affinity for the active site; substrate and product concentration effect the direction of reactions

Question 21

Give an account of the effects of competitive & non-competitive inhibition (4)

Answer 21

Competitive inhibition- The inhibitor resembles the substrate molecule; inhibition is reduced by increase in substrate concentration.
Non-Competitive inhibition-The shape of the active site changed; the inhibitor binds at a site other than the active site.