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:
- 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
|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.