Key Area 6

Question 1

What are metabolic pathways?

Answer 1

integrated, controlled and coordinated pathways of enzyme catalysed reactions in a cell

Question 2

What 3 things can a metabolic pathways have?

Answer 2

Reversible steps, irreversible steps and alternative routes

Question 3

What happens in a reversible metabolic pathway?

Answer 3

The presence of a substrate or removal of a product will drive a sequence of reactions in a particular direction

Question 4

What 2 things can reactions within a metabolic pathway be?

Answer 4

• anabolic

- catabolic

Question 5

What is an anabolic reaction?

Answer 5

A reaction which builds up large molecules from small molecules and requires energy

Question 6

What is a catabolic reaction?

Answer 6

A reaction which breaks down large molecules into smaller molecules and releases energy

Question 7

How are metabollic pathways controlled

Answer 7

By the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes

Question 8

What does every chemical reaction inside a cell require?

Answer 8

Energy

Question 9

What is the energy required for a chemical reaction to take place known as?

Answer 9

Activation Energy

Question 10

How do enzymes work?

Answer 10

They lower the Activation Energy

Question 11

What is an induced fit?

Answer 11

The active site changes slightly after a substrate binds to better fit the substrate

Question 12

What do substrate molecules have for the active site?

Answer 12

High affinity

Question 13

What do products have for the active site?

Answer 13

Low affinity

Question 14

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

Answer 14

The rate of reaction increases until all the active sites of the enzyme are involved in the reaction

Question 15

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

Answer 15

In most cases, the rate of reaction will decrease

Question 16

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

Answer 16

There will be an increase in conversion towards the product

Question 17

What happens to the direction of a reaction as a product concentration increases?

Answer 17

In most cases the direction of reaction will reverse and some product will be converted into intermediates of the reaction

If the product is used immediately or stored outside of the cell, the reaction will continue in the forward direction to ensure a continuous supply of product

Question 18

What is control of metabolic pathways affected by?

Answer 18

Inhibition of enzymes

Question 19

What are the 3 types of enzyme inhibition?

Answer 19

Competitive
Non- Competitive
Feedback

Question 20

What will all types of inhibitor do?

Answer 20

Decrease the rate of an enzyme controlled reaction

Question 21

What do competitive inhibitors do?

Answer 21

Bind at the active site preventing the substrate from binding

Question 22

What do non - competitive inhibitors do?

Answer 22

Bind away from the active site but the shape of the active site will change, preventing the substrate from binding

Question 23

What does feedback inhibition do?

Answer 23

Occurs when the end product in a metabolic pathway reaches a critical concentration

The end product then inhibits an earlier enzyme blocking the pathway and preventing further synthesis of end product.

Question 24

How can competitive inhibition be reversed?

Answer 24

By increasing substrate concentration

Question 25

Can non competitive inhibition be reversed by increasing substrate concentration?

Answer 25

No