Week 10 - Energy and Metabolism Flashcards
Why do we need ATP
Contraction of muscle
Biosynthesis of many substances
Movement of ions
Generation of heat
What is ATP made up of
Adenine
Ribose sugar
3 phosphate groups
What type of reaction does ATP go through to produce ADP
hydrolysis (addition of water)
3 food macromolecules
Carbohydrates, fats and proteins
Where does glycolysis occur
Cytosol of all cells
Does glycolysis require oxygen
No
What are the products of glycolysis
2 ATP, 2 pyruvate and and 2 NADH
What are the two phases of glycolysis
Initial investment phase
Energy payoff phase
What is 6 carbon glucose broken down into
2x 3 carbon glyceraldehyde-3-phosphate
Net gain of ATP in glycolysis
2 ATP
What are the two 3-glyceraldehyde-3-phosphates converted to in the energy payoff phase
2x 3c-pyruvate
What happens to pyruvate in the absence of oxygen
It is broken down into lactate by an enzyme called lactate dehydrogenase
If oxygen is absent what product of anaerobic respiration is used to propagate glycolysis
NAD+ since it is used up in the energy payoff phase.
What happens to pyruvate after glycolysis in the presence of oxygen
Pyruvate is transported to the mitochondrion and converted to acetyl coenzyme A by an enzyme called pyruvate dehydrogenase. 3c pyruvate loses a carbon to produce CO2 and NADH (which is fed to the electron transport chain.
What are the two phases of the citric acid cycle
Decarboxylating and reductive
What happens during the decarboxylating phase
6C citrate gets decarboxylated into 4C succinylcholine CoA, excess lost as CO2
What happens during the reductive phase
4C succinyl coenzyme A is reduced to produce 4C oxaloacetate. 4C oxaloacetate joins acetyl coenzyme A and cycle starts over
What is gained during the citric acid cycle
3NAD+ reduced to NADH
1FAD reduced to FADH2
What happens during the electron transport chain
NADH enters electron transport chain at complex 1
Proton is pumped out by complex 1
How is glucose stored in the body/liver/muscle
As glucose in the body and glycogen in the liver and muscle
How long do glycogen stores last in the body if not eating
16-24 hours
What happens when glycogen energy storage runs out
The body switches to lipid metabolism
How are lipids stored in adipose tissue
As triglycerides
What composes triglyceride
Glycerol
3 fatty acids
What type of enzyme releases fatty acids and glycerol
Lipase
When fatty acids are released from glycerol, what allows them to be transported in the blood
They attach to albumin
Where do fatty acids go in order to be metabolised
They are taken up by cells, modified and then travel to the mitochondrial matrix and undergo beta-oxidation
Describe the carnitine shuttle
Coenzyme A added by acetyl coenzyme A synthetase to produce fatty acyl CoA (can now pass through outer membrane. Uses ATP.
Coenzyme A is replaced with carnitine. Fatty acetyl carnitine is able to pass through inner membrane.
Once in matrix, carnitine is replaced with acetyl coenzyme A again in the matrix.
Cleavage of fatty acids occurs through what process and what does it involve
Beta-oxidation - cleavage of every second covalent bond between carbons
What happens during transamination
Amine group on the protein is removed
Amine group is donated to a-ketoglutamate (or similar)
Simultaneously, a-ketoglutamate donates ketone residue to the original amino acid forming a new ketoacid and a new amino acid (glutamate)
What are the two possible methods of protein metabolism
Deamination and transamination
What is deamination
Removal of amine group which takes place in the liver and causes the production of ammonium which is toxic
Ammonium is converted to urea
This releases carbon backbone of amino acid which can be regenerated into glucose, fatty acids or TCA cycle intermediates.
