2.4 Cofactors & Coenzymes

Question 1

What are cofactors and coenzymes?

Answer 1

Non protein components of enzymes

Question 2

What is a cofactor?

Answer 2

Inorganic molecule or ion

Question 3

What does a cofactor do?

Answer 3

Helps enzymes carry out their functions

Question 4

How might a cofactor help an enzyme?

Answer 4

• transferring atoms of groups between reactions

* form part of active site helping enzyme and substrate bind

Question 5

Are cofactors used up or changed in the reaction?

Answer 5

No

Question 6

How are cofactors bound to proteins?

Answer 6

Loosely

Question 7

How do cofactors participate in catalysis?

Answer 7

By taking part in active site

Question 8

What are coenzymes?

Answer 8

Organic

Question 9

What does organic mean?

Answer 9

Contain carbon

Question 10

Do coenzymes participate in reaction?

Answer 10

Yes

Question 11

Are coenzymes changed in reaction?

Answer 11

Yes

Question 12

What do coenzymes act as in the reaction?

Answer 12

Carriers

Moving chemical groups between enzymes

Question 13

What are vitamins a source of?

Answer 13

Coenzymes

Question 14

Give an example of a cofactor and what it is used for:

Answer 14

Cl- ions

Amylase requires them to form correctly shaped active site

Question 15

What is the coenzyme Vit B5 used for?

Answer 15

To make coenzyme a used in breakdown of fatty acids and carbohydrates in respiration

Question 16

What is the coenzyme Vit B3 used for?

Answer 16

To synthesise NAD - coenzymes responsible for transfer of H+ ions involved in respiration

Question 17

What is a prosthetic group usually made of?

Answer 17

Mineral ion

Question 18

How is a mineral ion bound to a protein?

Answer 18

Tightly

Question 19

What do prosthetic groups form?

Answer 19

Permanent feature of protein

Question 20

Zinc 2+ ions are a prosthetic group of what?

Answer 20

Carbonic anhydrase

Question 21

What is carbonic anhydrase?

Answer 21

Enzyme in red blood cells

Catalysed production of carbonic acid from water and carbon dioxide

Question 22

What do Zinc 2+ ions in carbonic anhydrase form?

Answer 22

Permanent part of active site

Question 23

What is the prosthetic group of haemoglobin?

Answer 23

HAEM

Question 24

How many polypeptide chains does haemoglobin have?

Answer 24

4

Question 25

What does each polypeptide of haemoglobin have?

Answer 25

HAEM prosthetic group

Question 26

What are inactive enzymes often called?

Answer 26

Inactive precursor enzymes

Question 27

What are inactive precursor enzymes activated by?

Answer 27

Changes in tertiary structure particularly the active site

Question 28

How is precursor activation ( change in tertiary structure) achieved?

Answer 28

Change in temp Change in ph addition of protease enzyme cofactor

Question 29

What is an enzyme called before activation?

Answer 29

Apoenzyme

Question 30

What is an enzyme called after activation with precursor?

Answer 30

Holoenzyme