Module 2.3 Enzymes

Question 1

What is an enzyme

Answer 1

It is a biological catalyst

Question 2

Where are biological catalyst found

Answer 2

In organism

Question 3

What are the two types of enzyme actions

Answer 3

They can be

1) Intercellular
2) Extracellular

Question 4

Name an intracellular enzyme and it’s function

Answer 4

Catalase

What does it do?

• It works inside cells to catalyse the breakdown of hydrogen peroxide.

Question 5

Why does catalase need to breakdown hydrogen peroxide

Answer 5

They need to do it because it is toxic.

If not removed can kill cells

Question 6

Give an example of an extra cellular enzyme

Answer 6

Amylase: secreted by salivary glands. Catalyses thé hydrolysis of starch into maltose

Trypsin- produced by pancreatic cells and secreted into small intestine catalyses the hydrolysis of peptide bonds. So turns polypeptides into smaller ones

Question 7

What is the structure of enzymes

Answer 7

They are globular protein (water soluble)

The active site is determined by the enzymes tertiary structure

Question 8

How do enzymes speed up reactions?

Answer 8

They lower the activation energy.

Question 9

What is a catabolic enzyme

Dirty mistresses club

Answer 9

An enzyme is catalysing a breakdown of reaction
It can put a strain on the substrates bond
Which will break it up easier

Question 10

What is an anabolic enzyme

The marriage councillor

Answer 10

It will reduce any repulsion between molecules by holding the substrates together so they can bond easier

Question 11

Describe the lock and key model

Answer 11

The enzyme is complimentary to the substrate
This means the enzyme is specific
The substrate will bind to the active site
An enzyme substrate complex forms
Then an enzyme product complex forms

Question 12

Describe the induced fit model

Answer 12

The enzyme is complimentary to the substrate
This means the enzyme is specific
The enzymes active site changes shape to accommodate the substrate
This forms an enzyme substrate complex
A reaction happens to from an enzyme product complex

Question 13

Why is amylase described as being extra cellular

Answer 13

It works outside a cell

Question 14

Suggest why the lock-and-key and induced-fit explanations are termed models

Answer 14

Because it a representation of how it works

Helps us visual the process

Question 15

Suggest why most scientists now accept the induced-fit model rather than the lock-and-key model.

Answer 15

There is more evidence/ new research

Question 16

Explain the term biological catalyst

Answer 16

1) enzymes are used in metabolism

2) lowers the activation energy

Question 17

Describe how an enzyme, such as pepsin, breaks down a substrate.

Answer 17

1. The substrate is complimentary to the shape of Pepsin
2. So pepsin is specific
3. Then the substrate binds to the active site of the enzyme
4. This forms an enzyme substrate complex
5. A reaction happens which puts strain on the bonds (forms a enzyme product complex)
6. The products leave the active site

Question 18

Name the covalent bond between two adjacent amino acids in a chain of amino acids.

Answer 18

Peptide bonds

Question 19

What factors affect enzyme activity

Answer 19

Temperature
ph
Substrate concentration
Enzyme concentration

Question 20

Describe and explain what happens to enzyme activity when temperature increases

Answer 20

1 Kinetic energy increases

2. More vibrations happen
3. Enzymes more likely to have frequent successful collisions with substrates
4. More enzyme substrate complex’s can form
5. After optimum ph the enzyme will denature

Why?

The increase in temperature will change the proteins tertiary structure, making the enzyme unable to work properly

Question 21

How does ph affect enzyme activity

Answer 21

If the ph is too acidic then it can break the hydrogen and ionic bonds in the enzymes tertiary structure

Making the enzyme denature

Question 22

What is Q10

Answer 22

how rate increases with 10 degrees

Question 23

What is a competitive inhibitor

Answer 23

• has a similar shape to the substrate
• competes with the substrate
• if successful will block the active site
• but this depends on how much substrate there is, as if the substrate is > then it can outcompete inhibitor

Question 24

Give an example of a competitive inhibitor

Answer 24

Antiviral or biotic drugs
penicillin catalyses the
the cell wall of bacteria

Question 25

What is a non-competitive inhibitor

Answer 25

• binds to the allosteric site
• changes shape of active site
• substrate can no longer bind to enzyme

Question 26

Give examples of non-competitive inhibitors

Answer 26

• Cyanide prevents respiration

- aresnick, malonate

Question 26

Give examples of non-competitive inhibitors

Answer 26

• Cynadie prevents respiration

- aresneic, malonate

Question 27

Give examples of non-competitive inhibitors

Answer 27

• Cynadie prevents respiration

- aresneic, malonate

Question 28

What is a reversible inhibitor

Answer 28

they bind to the active site for a short period and then leave.

when inhibitor is removed it leaves the enzyme unaffected

Question 29

What is an irreversible inhibitor

Answer 29

bind permanently to the enzyme molecule. Any enzyme molecules denatured if bound to

Question 30

How does the mechanism of end product inhibition work

Answer 30

• process slowed down when substrate made binds onto alternative site of enzyme
• can reattach when product is needed
• regulates the amount of substrate

Question 31

What is an apo-enzyme

Answer 31

inactive enzyme

Question 32

What is a holo enzyme

Answer 32

an activated enzyme

Question 33

How do we activate the apoenzyme

Answer 33

• through another enzyme
• through conditions like pH, temp
• through co factors

Question 34

What is a cofactor

Answer 34

• inorganic (na+, cl-)
• temporary bound to enzyme

eg chloride ions in amaylse

Question 34

What is a cofactor

Answer 34

• inorganic (na+, cl-)
• temporary bound to enzyme

eg chloride ions in amaylse

Question 35

What is coenzyme

Answer 35

• temporarily bound
• organic cofactors made from vitamins
• constantly recycled
• act as carriers

examples Nad required for alcohol dehydrogenase

Question 36

What is a prothetic group

Answer 36

• Permenantly bound to enzyme

- Example is Fe2+ , zinc ions in carbonic anhydrase