Lesson 5: Coenzymes and Cofactors

Question 1

What are Cofactors?

Answer 1

Molecule that allow some enzymes to only work in their presence

Question 2

What are Prosthetic Groups?

Answer 2

Cofactors that permanently bind covalent my to the enzyme

Question 3

Example of Prosthetic Groups

Answer 3

Carbonic Anhydrase
-Requires a cofactor in the form of a zinc ion
-Without the zinc it cannot catalyse carbon dioxide into carbonic acid, which enables carbon dioxide to be carried to the blood from respiring tissues to tge lungs

Question 4

Other Cofactors

Answer 4

-Some enzymes require cofactors that do not permanently bind to the enzyme
-They are still cofactors just not prosthetic groups
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Question 5

Example of a Cofactor

Answer 5

Amylase
-Can only digest starch into maltose if chloride ions are present
Calcium Ions
-Needed to catalyse the reaction of fibrinogen into fibrin by the enzyme thrombin

Question 6

How do Cofactors help?

Answer 6

-Act as co-substrates by binding to the substrate, making it the correct shape to fit into the active site of an enzyme
-Alter charge distribution on surface of substrate or active site, making temporary bonds that make forming the ESC easier

Question 7

What are Coenzymes?

Answer 7

-A larger type of cofactor
-Bind temporarily to the active site of an enzyme just before or at the same time as the substrate
-They are chemically changed in the reaction and need to be recycled

Question 8

Example of Coenzymes

Answer 8

Coenzyme A
-Needed in many metabolic pathways including for aerobic respiration
Vitamin B3 (Nicotinamide)
-Needed for the enzyme pyruvate dehydrogenase to work
-Lack of vitamin B3 can inhibit growth and development, and absence can cause the disease pellagra
-It is found in meat, poultry, fish, nuts, beans, cereals and potatoes