metabolic reactions (citric acid cycle) Flashcards
What is the fifth complex present in the electron transport chain?
ATP synthase
What is the chemiosmotic model?
chemical + electrical potential = proton motive force causing electrons to flow passively back causing ATP synthesis
What is the free energy of the hydrolysis of ATP?
-52 kj/mol
What does ATP synthase cycle through?
- ADP + Pi bound
- ATP bound
- empty
How are the subunits of ATP synthase rotated?
through the flow of protons
What does full rotation depend on?
the number of protons
How many protons produce 1 ATP molecule?
4
How much ATP do 1 NADH and FADH2 make?
1 NADH = 2.5 atp
1 FADH2 = 1.5 atp
Define oxidative phosphorylation?
the process by which ATP is synthesised as a result of transfer of electrons from NADH or FADH2 to O2
How can oxidative phosphorylation be uncoupled?
- through disruption of mitochondria or inhibiton of ATP synthase
What do venturicidin and oligomycin do to ATP production?
inhibit ATP synthase
What do uncoupling reactions do?
carry protons back to the matrix, dissipating the gradient
How are ATP levels regulated?
- by a cell’s energy demands
the mass ratio is usually high and a decrease results in rapid increase in respiration and oxidative phosphorylation
What is the starting material for the citric acid cycle?
Acetyl-coA
How does the number of carbon atoms change around the cycle?
from 2-6-6-5-4-4-4-4-4
What do oxidative decarboxylation and dehydrogenation reactions lead to?
the reduction of NADH and FADH2
What happens in the 1st step of the CAC?
oxaloacetate becomes citrate through a condensation reactions
What happens in the 2nd step of the CAC?
citrate becomes isocitrate
What happens in the 3rd step of the CAC?
isocitrate becomes a ketoglutarate through oxidative decarboxylation
What happens in the 4th step of the CAC?
a ketoglutarate becomes Succinyl-coA through oxidative decarboxylation
What happens in the 5th step of the CAC?
Succinyl - CoA becomes succinate
What happens in the 6th step of the CAC?
Succinate is oxidised to fumarate
- FAD is also reduced to FADH2
What happens in the 7th step of the CAC?
Fumarate is converted to fumarase through hydration
What happens in the 8th step of the CAC?
malate is oxidised to oxaloacetate, with the reduction of NAD+ to NADH
What does the sentence “can i ask some super fantastic memes on krebs cycle” stand for?
- citrate
- isocitrate
- a-ketoglutase
- succinyl coA
- succinate
- fumarate
- malate
- oxaloacetate
Is the citric cycle anabolic or catabolic?
neither. It is overall amphibolic, meaning that it includes both forms of reactions
What are anaplerotic reactions? what roles do they play in the CAC?
reactions that replenish the CAC intermediates
- they allow concentrations of the intermediates to remain constant
How is the CAC regulated?
allosteric regulation through inhibitors occurs.
Substrates and intermediates govern the rate of the cycle
