Difference Between Glycolysis and Krebs Cycle

Respiration is a process that occurs in all living beings in which oxygen is utilised and carbon dioxide is released from the body. The mechanism of cellular respiration involves the following mechanism:

  • Glycolysis
  • Anaerobic Breakdown of Pyruvic acid
  • Krebs Cycle
  • Electron Transport system
  • Terminal oxidation and oxidative phosphorylation
  • Pentose phosphate pathway

Here, in the article, let us discuss the difference between the Krebs Cycle and glycolysis but first let us take a look at what each of these terms means.

Glycolysis – It is an anaerobic process in which a molecule of glucose is converted into two molecules of pyruvic acid. It takes place in the cytoplasm

Krebs Cycle – It is an aerobic process that takes place in the mitochondria that involves the oxidation of pyruvic acid into water and carbon dioxide.

Given below in a tabular column are the differences between glycolysis and Krebs Cycle.

Glycolysis vs Krebs Cycle

Glycolysis Krebs Cycle
It is the first step in respiration in which glucose is broken down into two molecules of pyruvate Krebs Cycle is the second step of respiration in which it degrades pyruvate into inorganic substances (water and carbon dioxide)
Occurs inside the cytoplasm Occurs inside the mitochondria
No carbon dioxide evolved Carbon dioxide evolved
One molecule of glucose liberates 4 ATP molecules through substrate level phosphorylation Two acetyl residues liberate two ATP and GTP molecules through substrate level phosphorylation
Oxygen not required for glycolysis Oxygen is required for Krebs Cycle
Occurs as a linear sequence Occurs as a cyclic sequence
Consumes 2 molecules of ATP for initial phosphorylation of substance molecules Doesn’t consume ATP
Two molecules of ATP and two molecules of NADH gained for every molecule of glucose broken down Six molecules of NADH and two molecules of FADH2 for every acetyl-CoA oxidised

Both glycolysis and Krebs cycle are enzyme mediated and are under constant regulation based on the energy requirement of the cell/organism. The rates of these processes vary under various conditions such as the well-fed state, fasting state, exercised state and starvation state.

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