TCA Flashcards
What is the other name for the TCA?
Krbs cycle or tricarboxylic acid cycle
What is the basis of the TCA?
Using AcCoa, entering it into a cycle by oxaloacetate, creating CO2 waste and 3NADH, 1 FADH2 and 1 G/ATP
What is the first step of the TCA?
Acetyl COA is added to 4C oxaaloacetate, making citrate-and releasing HS-COA -overall transfering the 2C to the cycle
Where does the TCA happen?
in the mitochondrial matrix, except for succinate dehydrogenase, which is part of the IMM-as an Oxphos enzyme
What is the second and third step of the TCA?
Citrate is isomerised to isocitrate, and then, isocitrate dehydrogenase makes a-Ketoglutarate (5C), releasing 1NADH and 1 CO2
What is the 4th step of the TCA?
a-ketoglutarate gets the HS-COA readded, and another decarboxylation-making succinylCOA (4C), releasing 1 NADH and 1 CO2
What is the 5th step of the TCA? when does it make ATP and when GTP?
Succinyl COA has its HS-COA removed, making sccinate. This released 1GTP (or ATP in other tissues).
GTP itself is also a regulator for some signals, so usually ATP in muscle
What is the 6th step of the TCA?
Succinate is dehydrogenased to fumarate (4C)-releasing 1 FADH2
What are the 2 final steps of the TCA?
Fumarate (4C) has H20 added, making malate (4C). Finally, malate is dehydrogenased to oxaloacetate (4C)-and the cycle can be repeated
What does a full turn of the TCA produce?
3 NADH, 1 GTP and 1 FADH2 -but also numerous byproducts that can be used for other uses
What links amino acids and TCA? How are Amino acids treated?
The carbon skeletons of amino acids can be added to TCA as intermediates-and can either further the cycle or can be used to remake glucose (gluconeogenesis)-some amino acids can be glucogenic and Ketogenic. Amino acids have the amino group removed/ added to another keto acid by a transacetylation reaction AA+KETO = KETO + AA
How does NADH from glycolysis enter the mitocondrial matrix?
Malate aspartate shuttle ( usually in liver, kidney heart) or glycerol p shuttle (skeletal muscle, brain)
What is the idea of the glycerol phosphate shuttle?
The idea is that the electrons from NADH are transferred, not the NADH itself. 2 form of glycerol 3P dehydrogenase enzyme exist, one in the cytosol, one in the mitochondrial matrix. DHAP is made to G3P by the enzyme, using an NADH. THen the G3P is made to DHAP again by mitochondrial G3P dehydro, and the electons are transfered to FADH2, then to Ubiquinone
What is the idea of the a malate aspartate shuttle?
Again, the electrons are the one being transferred, this time through malate. The idea is that Oxaloacetate is made to malate (using NADH, providing NAD for glycolysis). This malate is sent to the MM, in exchange for an a-Ketoglutarate. The malate in the MM is made to oxaloacetate again, releasing the electrons. The Oxaloacetate is made to aspartate, taking the amino group from glutamate. The aspartate is released to cytosol, in excahnge for an exterior glutamate.
The aspartate remakes the oxaloacetate, transferring its amine group to the aketoglutarate (the one exchanged for the oxaloacetate), making glutamate to exchange for asp
So how much ATP is produced in total by Glycolysis + TCA
2 ATP for glycolysis, and 2 NADH, and 1 ATP, 3 NADH and 1 FADH2 from TCA PER ACETYLCOA. As 1 NADH is 3 ATP, and 1 FADH2 for 2 ATP -each TCA makes 12 ATP so 1 glucose makes 2+12x2+6=32 ATP
