2.4.2. Cofactors

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  • Created by: shyde7
  • Created on: 19-05-16 15:52
Which enzymes in particular can only work if cofactors are attached?
Enzymes used in catalysing oxidation-reduction reactions.
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What is a prosthetic group?
A cofactor that is permanently bound by covalent bonds to an enzyme molecule.
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What is the prosthetic group of carbonic anhydrase?
A zinc ion.
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What is good about most enzyme-catalysed reactions?
They are reversible (they can go in either direction)
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What does this depend on?
The concentration of substrate or product molecules.
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Where is zinc needed in the human body?
It is needed for insulin (a polypeptide hormone) to function correctly.
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Which people may have zinc deficiencies?
People whose diets do not contain much meat.
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What can help these people have more zinc in their diets?
A genetically modified crop plant (e.g. plantain - a type of banana).
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Where is plantain useful?
In places like East Africa where people may not be able to obtain much meat.
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Why are cofactors important?
They may ease the formation of enzyme-substrate complexes and therefore increase the rate of a reaction.
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What is a co-substrate?
A cofactor that binds to the substrate to give the molecule the correct shape to bind to the active site.
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How else can cofactors help form enzyme-substrate complexes?
They can change the charge distribution to make the temporary bonds easier to form.
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What is the cofactor of amylase?
Chloride ions.
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What are coenzymes?
They are like cofactors, but bind to the active site rather than the surface.
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What happens to coenzymes during a reaction?
They are chemically changed and so have to be recycled back to the cell - sometimes this is catalysed by another enzyme.
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Where are many coenzymes derived from?
Water-soluble vitamins.
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What happens if there are vitamins missing from an individual's diet?
Diseases may occur.
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What is the coenzyme derived from vitamin B12?
Cobalamin conenzymes.
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What is the disease that may result from a deficiency of B12?
Pernicious anaemia.
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What is the coenzyme derived from folic acid?
tetrahydrofolate
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What is the disease that may result from a deficiency of folic acid?
Magablastic anaemia
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What is the coenzyme derived from Pantothenate, B6?
Coenzyme A
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What is the disease that may result from a deficiency of Pantothenate, B6?
Elevated blood-plasma triglyceride levels.
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What is the coenzyme derived from Thiamine, B1?
Thiamine pyrophosphate
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What is the disease that may result from a deficiency of Thiamine, B1?
Beriberi
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What are NAD and NADP?
Hydrogen acceptors that are both derived from nucleotides.
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Card 2

Front

What is a prosthetic group?

Back

A cofactor that is permanently bound by covalent bonds to an enzyme molecule.

Card 3

Front

What is the prosthetic group of carbonic anhydrase?

Back

Preview of the front of card 3

Card 4

Front

What is good about most enzyme-catalysed reactions?

Back

Preview of the front of card 4

Card 5

Front

What does this depend on?

Back

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