Lecture 20 Flashcards
(36 cards)
What is stage 1?
The generation of acetyl coA and a pair of electrons
What is stage 2?
Is the oxidation of the two carbon atoms from acetyl CoA in the Citric Acid Cycle to form two CO2 molecules and four pairs of electrons
What is stage 3?
Electron transport and oxidative phosphorylation. It is where reduced electron carriers that were generated from Stages 1 & 2 become re-oxidized, thus providing energy for the synthesis of ATP.
What is the first reaction in the CAC?
It is the combination of acetyl CoA and oxaloacetate to produce the compound of citroyl CoA, and THEN, citrate. This is a exergonic reaction of free energy.
What are the two reactions that happen to produce citrate?
Condensation followed by hydrolysis. This happens because of proton transfers on acetyl CoAA that activate enol attack on carbonyl group of OAA. Spontaneous hydrolysis of citroyl CoA caues cleaving that results in citrate. All catalyzed by citrate synthase.
How does the 2 part reaction promote correct reaction?
promote the correct reaction, but also prevent wasteful side reactions (e.g. hydrolysis of acetyl CoA without using its energy).
How does citrate synthase function?
As a homodimer
What type of fit is citrate synthase?
It is a induced fit reaction where oxaloacetate binds first and acetyl coA
What is second step in the CAC?
It is the aconitase reaction.
What happens to citrate in the second step of the CAC?
It is in the wrong place because it is a tertiary alcohol where the hydroxyl group is in the wrong place.
What needs to happen for the citrate to be moved?
The enzyme aconitase will catalyze a dehydration /hydration reaction. It will leave in the form of water (dehydration) forming cis-aconitate and remains enzyme bound. Next, water is combined with cis-Aconitate (hydration rxn) to form D-Isocitrate. This is an endergonic reaction that requires free energy.
What is the third step of the CAC?
An oxidative decarboxylation reaction. This is the oxidation of Isocitrate to α-ketoglutarate generates the electron carrier NADH. CO2 is also released during this reaction.
Where does the CAC cycle happen?
In the matrix of the mitochondria
What is a tertiary alcohol?
where a alcohol is bound to one carbon who is bound to 3 other carbons
What is the isocitrate dehydrogenase reaction?
It is where it loses hydrogens and go to NAD. NAD is reduced to NADH. This is where isocitrate is gonna become oxalosuccinate and then alpha ketoglutarate. This is a free energy rxn that is favorable.
What happens after making alpha ketoglutarate?
It is converted into succinyl coA through oxidation and decarbolyxation that generates another NADH. Mainly occurs through α-Ketoglutarate Dehydrogenase
What is the fourth step of the CAC?
There is the combiantion of alpha ketoglutarate + NAD + coA SH come on as CO2. Then, yields succinyl CoA and CO2 and NADH.
What happens to succinyl CoA?
It is turned into GTP (ATP).
What is the fifth step of the CAC?
succinyl is turned into GTP and is catalyzed by succinyl CoA synthetase.
What is true about GTP?
It allows cells to use GTP as an energy source as it is readily converted to ATP
What catalyzes GTP to ATP?
nucleoside diphosphokinase
What is the sixth step of CAC?
The oxidation of succinate to fumarate through succinate dehydrogenase. This also generates FADH 2. This is bc FAD is a hydrogen acceptor.
What is the process from succinate to fumarate to malate and then oxaloacetate?
oxidation then hydration then oxidation again
What is the seventh step of CAC?
The hydration reaction of fumarate to malate because water enters and replaces the hydrogens lost. This is catalyzed by fumarase
