What is the main function of the krebs cycle?
Answers
Answer:
The citric acid cycle, also known as the Krebs cycle or the tricarboxylic acid cycle, is at the center of cellular metabolism, playing a starring role in both the process of energy production and biosynthesis. It finishes the sugar-breaking job started in glycolysis and fuels the production of ATP in the process.
Explanation:
Regulation of the TCA cycle
Regulatory steps of the TCA cycle:
1) Citratesynthase
2) Isocitratedehydrogenase
3) α-ketoglutaratedehydrogenase
Regulatory factors of the TCA cycle:
1) NADH/NAD+ ratio – respiratory control
2) ATP/ADP (AMP) ratio – energetic control
3) Availability of substrates for the TCA cycle – substrate control
1) NADH/NAD+ ratio – respiratory control
The TCA cycle continues to the ETC. Reoxidation of the reduced coenzymes takes place there. In situations when is the ETC slowed, NADH and FADH2 accumulate. It is obvious that NADH/NAD ratio increases and thus α-ketoglutaratedehydrogenase and isocitratedehydrogenase are inhibited.
2) ATP/ADP (AMP) ratio – energetic control
α-ketoglutaratedehydrogenase and isocitratedehydrogenase are inhibited when there is a sufficient amount of energy, i.e. ATP/ADP (AMP) ratio is high. ATP acts as inhibitor, ADP and AMP are activators of those two enzymes.
3) Availability of substrates for the TCA cycle – substrate control
As you know, velocity of the chemical reaction depends among others on the concentration of the reactants and the products. Velocity of the TCA cycle depends on the concentration of the citrate. Activity of the citratesynthase is related to amounts of oxaloacetate and AcCoA that are provided.
Activity of the TCA cycle is interwoven with the availability of the oxygen despite the fact that none of the reactions of the TCA cycle require oxygen. Oxygen is vital for the ETC. Oxygen is the final acceptor of the electrons. In the ETC reoxidation of the NADH → NAD+ and FADH2 → FAD take place. One can easily deduce that reduction of the oxygen supplies for the cell leads to drop of concentrations of the NAD+ and FAD, hence activity of the TCA cycle is decreased.