Citric acid cycle Flashcards
Describe why the 8 vitamin Bs are important for metabolism. Include the vitamin B precursors used in the synthesis of essential cofactors of the PDH complex and also pyruvate carboxylase.
1) Thiamine Synthesises of TPP, α-Ketoglutarate complexes and Pyruvate decarboxylase. Used in PDH complex 2) Riboflavin Synthesised FAD and FMN. Redox chemistry 3) Niacin NADH and NADPH. Redox chemistry 4) Pyridoxine Pyridoxal phosphate. Aminotransferase (adds amine to one end) 5) Pantothenic acid Coenzyme A. Oxidation of fatty acids 6) Biotin Pyruvate carboxylase 7) Folic acid THF. Amino acid synthesis 8) Cobalamine Met synthesis and branched chain AA catabolism
What is the purpose of the citric acid cycle?
Generates NADH, GTP(ATP), and FADH2
Which two reactions in the citric acid cycle are irreversible?
Acetyl-CoA + Oxaloacetate converted to citrate by citrate synthase and cofactor H2o
alpha-KG converted to Succinyl-CoA by the alpha-Ketoglutarate dehydrogenase complex using cofactors NAD+ and CoA-SH
What are the allosteric regulators of Isocitrate to alpha-KG?
\+ = ADP - = ATP, NADH
What are the allosteric regulators of alpha-KG to Succinyl-CoA?
- = ATP, Succinyl-CoA, NADH
Why does citrate to isocitrate go in the forward’s direction when the backward direction is preferred?
Driven forwards by the rapid consumption of isocitrate
Which two steps in the citric acid cycle are made up of two reactions?
Citrate to cis-Aconitate to Isocitrate
Fumarate to Carbonion Transition state to L-Malate
Overall production of ATP per glucose
30-32
2ATP, 10NADH, 2FADH2, 2GTP
What is different about the electron transport chain in the brain and skeletal muscle cells compared to the liver, kidney, and heart cells?
Brain and skeletal muscle cells forgo complex I, and so only produce 30 ATP, and this is because this chain begins outside the inner membrane, not within it.
liver, kidney had heart cells will include complex I in their ETC, and so produce 32 ATP as four extra protons are pumped out.
Where is the malate-aspartate found?
Liver, Kidney, and heart cells. Shuttle across the inner membrane to the matrix and back
How many ATP does the malate-aspartate shuttle yield per NADH
2.5 ATP when electrons from cytosolic NADH are transported via the shuttle.
How does the malate-aspartate shuttle work?
NADH in cytosol converted to malate. This is then transported into the matrix across the inner membrane through the alpha-malate ketoglutarate transporter which then allows the malate to become oxaloacetate
Where is the Glycerol-3-phosphate shuttle found?
In Brain and skeletal muscle cells. This shuttle occurs in the intermembrane space.
How many ATP does the glycerol-3-phosphate shuttle yield per NADH
1.5 ATP when electrons from cytosolic NADH are transported via Glycerol-3-phosphate shuttle
How does the Glycerol-3-phosphate shuttle work?
Glycerol-3-phosphate is converted to dihydroxyacetone while reducing FAD to FADH2. FADH2 then interacts with co enzyme Q, carrying it through complex III (Missing complex I)
