Mastering Cellular Respiration: The Role of the Krebs Cycle

Mastering Cellular Respiration: The Role of the Krebs Cycle


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  • Source: Microbioz India

  • Date: 13 Feb,2024

What is involved in the mastery of cellular respiration? In simple terms, it means understanding how important the Krebs cycle is for generating energy during cellular respiration.

Krebs cycle and its significance in cellular energy production:

Where does the krebs cycle take place? :

Mitochondrial matrix, the innermost compartment of mitochondria, known as energy hubs because they produce ATP; it is here that Krebs cycle occurs.


TCA or the Krebs cycle pathway is a central metabolic pathway burning different types of fuel molecules such as glucose, fatty acids and amino acids via acetyl-CoA to generate NADH, FADH2 and GTP/ATP which are high energy compounds.

Key Steps:

  1. Acetyl-CoA Entry: The fusion of acetyl-Co A with oxaloacetate is brought about by citrate synthase enzyme.
  2. Subsequent Reactions: In this case, enzymes controlled reactions that occur in a cyclical manner throughout malate from previous steps.
  3. Decarboxylation: Decarboxylation reactions liberate CO2 while NADH and FADH2 are also formed.
  4. Substrate-level Phosphorylation: The next reaction involves conversion of succinyl-CoA into succinate leading to GTP which can be converted to ATP afterwards.
  5. Regeneration of Oxaloacetate: In the final step, malate dehydrogenase converts malate back into oxaloacetate again initiating another round of Glycolysis Cycle.

Role in ATP Production:

  1. In short, NADH and FADH2 are produced during glycolysis process as reducing equivalents which then transfer their electrons to mitochondrial inner membrane’s electron transport chain (ETC).
  2. Transfer of electrons down this chain releases energy used by the respiratory complex I-IV pumps protons across the mitochondrial membrane. This movement creates an electrochemical gradient that drives oxidative phosphorylation resulting in synthesis of ATP through chemiosmotic coupling mechanism by ETC.

Integration with Other Pathways:

  1. The Krebs cycle is not an isolated pathway but it is interconnected with other metabolic pathways. For example, Amino acids, nucleotides and heme in general are all synthesized from various intermediates of the TCA cycle.
  2. In addition, energy demand of the cell availability of substrates and allosteric modulation of critical enzymes modulate the regulation of Kreb’s cycle.


Regulation by product inhibition, substrate availability and allostery characterize enzymes within it. Inhibitory effects on several enzymes in this pathway can be experienced when their level is high leading to decrease their activity due to ATP or NADH saturation.

The summary is that the Krebs cycle plays a significant role in cellular respiration as it provides a controlled oxidation mechanism for Acetyl-CoA and helps to store energy that will be used later on during ATP generation. Mastery of its intricate details therefore forms a basis for understanding cellular respiration as interplay between different aspects involved in cellular metabolism.

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