Difference Between Glycolysis and Krebs Cycle: Overview, Examples

What Is Respiration?

Respiration is an extremely basic process happening in all living organisms. It involves the use of oxygen and giving out carbon dioxide. The three stages of cellular respiration entail glycolysis, the Krebs cycle, and the electron transport chain. We will dwell on the differences between the two imperative pathways of energy metabolism: glycolysis and the Krebs cycle.

Glycolysis

Glycolysis is the first step in cellular respiration, occurring in the cytosol of the cell and being an anaerobic process. This stage of glycolysis involves the partial breaking down of a six-carbon sugar into two three-carbon compounds: pyruvic acid. There are ten enzymatic reactions coupled to a net gain of two ATP molecules and two NADH molecules in this process.

Key Features Of Glycolysis Location

Cytoplasm Starting material: Glucose End Products: Two molecules of pyruvic acid Two molecules of ATP with a net gain Two molecules of NADH Oxygen Requirement: No requirement of oxygen, hence it is an anaerobic process Function: It converts glucose into pyruvate, which in turn enters the Krebs cycle or is converted into lactate/ethanol under anaerobic conditions.

Krebs Cycle

The Krebs cycle, sometimes known as the citric acid or TCA cycle, is a process happening in the mitochondrial matrix of eukaryotic cells. It is an indirectly oxygen-dependent process in that it relies on the electron transport chain, which works only when oxygen is present. The Krebs cycle is the process following glycolysis and is responsible for the complete oxidation of pyruvate into carbon dioxide.

The major features of the Krebs cycle thus include:

1. Location: Mitochondrial matrix

2. Starting Material: Acetyl-CoA, which is derived from Pyruvate

3. End Products: For every acetyl-CoA that enters the cycle, the end products are three molecules of NADH, one molecule of FADH2, one molecule of GTP (or ATP), and two molecules of carbon dioxide

4. Oxygen Requirement: Indirectly requires oxygen; thus, it is an aerobic process

5. Function: oxidizes acetyl-CoA, producing energy careers in the form of NADH and FADH2, with Carbon-di-oxide as byproducts

Differences Between Glycolysis And Krebs Cycle

Here is a table comparing the key differences between glycolysis and the Krebs cycle:

Relationship Between Glycolysis And Krebs Cycle

The cycles of glycolysis and Krebs are interlinked. During glycolysis, pyruvate is generated that can be converted into acetyl-CoA, a substrate that enters into the Krebs cycle. As a result of this interlinking, cells can make the best use of glucose to produce energy mostly under aerobic conditions.

Regulation Of Glycolysis And Krebs Cycle

Both the glycolysis and Krebs cycle are mediated by enzymes, and their rates are changed depending on the requirement of energy in the cell. These rates may be different under various physiological conditions such as during fasting, exercise, and starvation.

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