Unit 1-Metabolic Pathways

Question 1

What are metabolic pathways?

Answer 1

Metabolic pathways are enzyme-catalysed reactions within a cell.

Question 2

All of the metabolic pathways in an organism

Answer 2

Metabolism

Question 3

What are the two types of metabolic pathways?

Answer 3

Anabolic and catabolic.

Question 4

What is cell metabolism?

Answer 4

The collective term for all the biochemical reactions that occur in a living cell.

Question 5

What do anabolic reactions do?

Answer 5

Anabolic reactions build up molecules from small molecules and requires energy.

Question 6

What do catabolic reaction do?

Answer 6

Catabolic reactions break down large molecules into smaller molecules and release energy.

Question 7

In a metabolic pathway, what controls each step?

Answer 7

Enzymes.

Question 8

What are enzymes?

Answer 8

Biological catalysts which speed up chemical reactions within living things.

Question 9

What are enzymes that work inside a cell?

Answer 9

Intracellular enzymes.

Question 10

What are enzymes that work outside a cell?

Answer 10

Extracellular enzymes (pepsin in the stomach).

Question 11

During a chemical reaction, what is energy needed for?

Answer 11

Energy is needed to break chemical bonds during a chemical reaction.

Question 12

What is the energy needed to break the chemical bonds in a chemical reaction called?

Answer 12

The activation energy.

Question 13

What do enzymes do to the activation energy needed for a reaction to proceed?

Answer 13

Enzymes lower/decrease the activation energy

Question 14

What is the region of an enzyme which allows the substrate to bind?

Answer 14

Active Site

Question 15

What is induced fit?

Answer 15

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 16

What does affinity mean?

Answer 16

An attraction for something.

Question 17

If a substrate has a high affinity for the active site, what does the active site do?

Answer 17

The active site works by holding 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 18

Once the reaction has taken place, what happens to the products?

Answer 18

Since the products have a low affinity for the active site, they are released.

Question 19

What can enzyme activity be affected by?

Answer 19

Temperature.
pH.
Substrate concentration.
Concentration of product.
Inhibitors.

Question 20

As the concentration of a substrate increases, what also increases?

Answer 20

The reaction rate.

Question 21

All of the enzyme’s active sites have become occupied with substrates, what is now the limiting factor?

Answer 21

Enzyme concentration.

Question 22

When all of the enzymes are occupied by substrates what is this called?

Answer 22

The point of saturation.

Question 23

What is an inhibitor?

Answer 23

An inhibitor is a substance that decreases the rate of an enzyme-controlled reaction.

Question 24

What are the three types of inhibition?

Answer 24

Competitive inhibition

Non-competitive inhibition

Feedback inhibition

Question 25

Competitive inhibition

Answer 25

Inhibitor molecule binds to the active site of the enzyme and stops the substrate from binding

Question 26

What property of a competitive inhibitor allows it to compete with the substrate?

Answer 26

They have a similar molecular shape allowing them to bind to the enzyme’s active sites.

Question 27

How can competitive inhibition be reversed?

Answer 27

By increasing substrate concentration.

Question 28

Non-competitive inhibition

Answer 28

Inhibitor does not bind to the active site but does bind to a different part of the enzyme and changes the active site shape.

Question 29

Will increasing substrate concentration reverse non-competitive inhibition?

Answer 29

No

Question 30

Feedback inhibition

Answer 30

End product in a metabolic pathway binds to an enzyme at the start of the pathway stopping metabolic pathway