Metabolic Pathways

Question 1

What are metabolic pathways?

Answer 1

Integrated and controlled
pathways of enzyme–catalysed
reactions within a cell

Question 2

Name the 2 types of reactions
which can occur within metabolic
pathways

Answer 2

Anabolic and catabolic

Question 3

Describe anabolic reactions

Answer 3

Synthesis reactions in which small
molecules build up into bigger ones

Question 4

Describe catabolic reactions

Answer 4

Degradation reactions in which
large molecules are broken down
into smaller ones

Question 5

Which reaction requires energy?

Answer 5

Anabolic

Question 6

Which reaction releases energy?

Answer 6

Catabolic

Question 7

How are metabolic 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 is an induced fit?

Answer 8

When the active site of an enzyme
changes shape to better fit the
substrate after the substrate
binds

Question 9

The affinity of the substrate
molecule(s) for the active site

Answer 9

High affinity

Question 10

The affinity of the products for
the active site of an enzyme

Answer 10

Low affinity

Question 11

The importance of products having
a low affinity for the enzyme
active site?

Answer 11

Allows them to leave the active
site of the enzyme

Question 12

What is the activation energy of a
reaction?

Answer 12

The minimum energy required to
start a chemical reaction

Question 13

What effect does an enzyme have on
the activation energy of a reaction?

Answer 13

Lowers the activation energy

Question 14

How can increasing the substrate
concentration affect the rate of
reaction?

Answer 14

It can increase the reaction until
the enzymes’ active sites are all
used

Question 15

What effect does increasing the end
product concentration have on the
rate of reaction?

Answer 15

It can reduce the rate of reaction,
stop or reverse the reaction

Question 16

Some reactions are reversible.
What causes the reaction to
proceed in a particular way?

Answer 16

The presence of a substrate or
removal of a product

Question 17

The term for a substance which can
slow or stop an enzyme’s action

Answer 17

Inhibitor

Question 18

How do competitive inhibitors work?

Answer 18

They bind at the enzyme’s active
site and prevent the substrate
from binding

Question 19

How can competitive inhibition be
reversed?

Answer 19

By increasing substrate
concentration

Question 20

How do non-competitive inhibitors
work?

Answer 20

They bind at an area other than the active site but change the shape of the active site and prevent the substrate from binding

Question 21

The type of inhibition that can not
be reversed by increasing substrate concentration

Answer 21

Non-competitive inhibition

Question 22

When does feedback inhibition
occur?

Answer 22

When the end product in the
metabolic pathway reaches a
critical concentration

Question 23

How does the end-product inhibit
the metabolic pathway?

Answer 23

The end-product inhibits an earlier enzyme in the pathway, blocking the pathway and preventing further synthesis of the end product