Cofactors and Coenzymes 4.4

Question 1

Cofactors

Answer 1

Non-protein helpers that bind to the enzyme and help it carry out its function. It may be found on the active site of the enzyme or it may transfer atoms from other groups.

Question 2

Coenzymes

Answer 2

Organic cofactors

Question 3

Where are cofactors found?

Answer 3

They are found in the diet as minerals and ions. For example, amylase has a chloride ion that is necessary for it to form the correct active site to break down amylose.

Question 4

Where are coenzymes found?

Answer 4

They are found in the diet as vitamins. NAD is a coenzyme needed during photosynthesis and respiration, it’s taken from vitamin B3.

Question 5

Prosthetic groups

Answer 5

These are cofactors that form a more permanent part of the protein e.g. haem groups on haemoglobin. Some enzymes can be loosely bound, whereas prosthetic groups are tightly bound to the protein.

Question 6

Precursor enzyme

Answer 6

They are produced in an inactive form and can cause damage to the cell or have to be controlled which is why they have to be activated.

Question 7

Precursor activation

Answer 7

A cofactor will bind to the precursor enzyme and change its active site which will then activate it so it can carry out its function

Question 8

Apoenzyme

Answer 8

Precursor enzyme before the cofactor is added

Question 9

Holoenzyme

Answer 9

Precursor enzyme after the cofactor has been added

Question 10

Zymogens

Answer 10

Precursor enzymes that change their tertiary structure due to a change in the environment.