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Question 1

ATP can be used as

Answer 1

Energy storage

Question 2

a carbon skeleton of amino acid

Answer 2

Question 3

a free amino group of amino acid

Answer 3

Question 4

Deamination generates? What is it?

Answer 4

• a free amino group
• a carbon skeleton
  Removal of amino group

Question 5

Two ways amino acids can be delaminated

Answer 5

• by releasing their amino groups to solution
• by transferring their amino group to a keto acid

Question 6

Amino acid being delaminated by realsing their amino groups to solution - process

Answer 6

e.g. glutamate deamination catalyzed by glutamate dehydrogenase (GDH)

(Ketone group added)

Question 7

Amino acid being deaminated by transferring their amino group to a keto acid
- process

Answer 7

Known as a transamination
Catalysed by aminotransferase enzymes (transmainases)
- involves a co-enzyme

Question 8

Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) is derived from…

Answer 8

Derived from vitamin B6

Question 9

Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) - what does it do

Answer 9

Carries: amino group (from the amino acid to the keto acid)

Question 10

Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) - what forms can it exist in?

Answer 10

Exists in two forms:
- Pyridoxal phosphate (no amino group)
- Pyridoxamine phosphate (with amino group)

Question 11

Transamination reactions involve ___ steps

Answer 11

Two

Question 12

Transamination first step

Answer 12

Amino group is transferred from the amino acid to the pyridoxal phosphate (becomes pyridoxamine phosphate)

Question 13

Transamination second step

Answer 13

Amino group is transferred pyridoxamine phosphate (becomes pyridoxal phosphate) to the keto acid

Question 14

There are some common amino acid/ keto acid pairs in metabolism

Answer 14

Question 15

Keto acids can be fed into the metabolic pathways

Answer 15

Some keto acids can directly enter metabolic pathways, some keto acids require modification first

Question 16

Transamination reactions are also required to remove excess ____ via the _____

Answer 16

Nitrogen
Liver

Question 17

Transamination reactions are also required to remove excess nitrogen via the liver
- process

Answer 17

Question 18

Outline the two phases of glycolysis
(2 marks)

Answer 18

The first phase is the activation (or energy input) phase
where energy is used to get the molecule into a form
where energy can be extracted.
The second phase is the energy output phase where
energy from the molecule is used to phosphorylate ADP
to make ATP.

Question 19

Q. Under anaerobic conditions, pyruvate from glycolysis is
converted to lactate by lactate dehydrongenase (LDH).
Describe why this reaction is necessary for ATP
synthesis under anaerobic conditions

Answer 19

In anaerobic conditions mitochodrial pathways are not
working so glycolysis (in the cytplasm) is the only pathway
making ATP.
Glycolysis needs NAD + to provide oxidising powder. As
coenzymes are not being regenerated in the mitochondria
in anaerobic conditions and in low amounts in cells, NADH
will build up stopping glycolysis. The LDH reaction also
oxidises NADH back to NAD. The NAD+ can then keep
glycolysis going to continue making ATP in anarobic
conditions.

In glycolysis NAD + is reduced in a key reaction catalysed by
glyceraldehyde-3-phosphatedehydrongenase (GAPDH). In aerobic
conditions the NADH is oxidized back to NAD+ in the mitochondria, but
this does not happen in anaerobic conditions. NAD has a low
concentration in cells, so if glycolysis is happening in anaerobic conditions
there will be a build up of NADH and the GAPDH reaction will not have
enough oxidizing power from NAD+. The reaction catalysed by LDH is
important because in the reaction NADH is oxidised to NAD+ so glycolysis
can continue.
Under anaerobic conditions the other ATP synthesis pathways are not
working as they rely on oxygen. Therefore, the LDH reaction regenerating
the NAD+ so glycolysis can continue is necessary for some ATP synthesis
under anaerobic conditions.