31 Flashcards
ATP can be used as
Energy storage
a carbon skeleton of amino acid
a free amino group of amino acid
Deamination generates? What is it?
- a free amino group
- a carbon skeleton
Removal of amino group
Two ways amino acids can be delaminated
- by releasing their amino groups to solution
- by transferring their amino group to a keto acid
Amino acid being delaminated by realsing their amino groups to solution - process
e.g. glutamate deamination catalyzed by glutamate dehydrogenase (GDH)
(Ketone group added)
Amino acid being deaminated by transferring their amino group to a keto acid
- process
Known as a transamination
Catalysed by aminotransferase enzymes (transmainases)
- involves a co-enzyme
Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) is derived from…
Derived from vitamin B6
Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) - what does it do
Carries: amino group (from the amino acid to the keto acid)
Pyridoxal phosphate (PLP) (a co-enzyme required for transamination reactions) - what forms can it exist in?
Exists in two forms:
- Pyridoxal phosphate (no amino group)
- Pyridoxamine phosphate (with amino group)
Transamination reactions involve ___ steps
Two
Transamination first step
Amino group is transferred from the amino acid to the pyridoxal phosphate (becomes pyridoxamine phosphate)
Transamination second step
Amino group is transferred pyridoxamine phosphate (becomes pyridoxal phosphate) to the keto acid
There are some common amino acid/ keto acid pairs in metabolism
Keto acids can be fed into the metabolic pathways
Some keto acids can directly enter metabolic pathways, some keto acids require modification first
Transamination reactions are also required to remove excess ____ via the _____
Nitrogen
Liver
Transamination reactions are also required to remove excess nitrogen via the liver
- process
Outline the two phases of glycolysis
(2 marks)
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.
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
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.
