Glycolysis vs Fermentation: Difference and Comparison

Various chemical processes take place all around us. But, despite our lack of interest, we are once again confronted with two such common phenomena: glycolysis and fermentation.

The process starts in the living organisms’ cells. They are unmistakably dissimilar, but how dissimilar are they?

This is something we’ll look into in this article.

Key Takeaways

  1. Glycolysis is a metabolic process that breaks down glucose into pyruvate, while fermentation converts pyruvate into various end products.
  2. Glycolysis occurs in the cytoplasm of cells and does not require oxygen, whereas fermentation can be either aerobic or anaerobic.
  3. Fermentation allows cells to regenerate NAD+ for continued glycolysis, especially in anaerobic conditions.

Glycolysis vs Fermentation 

Glycolysis is an anaerobic process that breaks down glucose into two molecules of pyruvate, producing ATP and NADH, which can be used to generate more ATP through aerobic respiration. Fermentation allows cells to produce ATP in the absence of oxygen, regenerating NAD+ for use in glycolysis.


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Glycolysis vs Fermentation

Glycolysis is the first step in the process of cellular respiration.

The process begins with the breakdown of glucose, a six-carbon molecule that is split into two molecules with three carbon atoms each.

The process can occur both in the presence of oxygen and in the absence of oxygen.

On the other hand, fermentation is an anaerobic chemical reaction that occurs as part of cellular respiration. Anaerobic respiration is another term for fermentation.

The reaction takes place in the cytoplasm of eukaryotic cells. This mode of reaction is also less efficient than the first because it occurs when oxygen is scarce.

Comparison Table

Parameters of comparison Glycolysis Fermentation 
Does it take in presence of oxygen?Yes No 
Occurrence Mitochondria Cytoplasm 
How many ATP molecules does it produce?4 ATP molecules2 ATP molecules
Chemical conversion Glucose to pyruvate Pyruvate to lactic acid and alcohol 
End products 2 pyruvate molecules, 4 ATP molecules, and two NADH.CO2, ethanol, and energy.

What is Glycolysis?

Food is used as fuel by an organism, and the food is converted into fuel through a series of chemical reactions. We’re talking about glycolysis, the first stage of cellular respiration.

It aids in forming ATP, or Adenosine Triphosphate, a type of energy molecule. The breakdown of the glucose molecule is the first step in the glycolysis process.

Six carbon atoms make up a glucose molecule. The procedure can be performed in the presence or absence of oxygen.

In the presence of oxygen, glycolysis progresses to Kreb’s cycle. The electron transfer change step in the Krebs cycle follows the citric acid cycle.

ATP is initially produced in this step.

Though the process’ main goal is to produce energy (ATPs), it begins by breaking down glucose with the help of two ATP molecules. The glucose is split into two molecules, each with three carbons.

These two-three carbons, or phosphoglyceraldehyde, are then converted into pyruvate, a three-carbon molecule.

It’s also worth noting that each phosphoglyceraldehyde generates two ATP molecules, for a total of four ATP molecules and NADH. In the ETC phase, NADH aids in the production of ATPs.

The most important thing to remember is that glucose is converted into pyruvate molecules.

What is Fermentation?

In contrast, fermentation is an anaerobic chemical reaction that takes place during cellular respiration. Anaerobic respiration is another name for fermentation.

The reaction takes place in the cytoplasm of eukaryotic cells. This mode of reaction is less efficient than the first because it occurs when oxygen is scarce.

Fermentation can take two forms: one occurs in plants and yeast, and the other occurs in animals. It’s worth noting that yeasts are single-celled organisms.

Glucose is the fundamental molecule for both types; as previously stated, it is a six-carbon atom molecule.

What distinguishes the two types of plants, yeast, and animals are their end products. It produces ethanol, carbon dioxide, and energy in plants and yeasts.

Exothermic processes are those that release energy, which is why respiration is called an exothermic process.

Animals, on the other hand, produce lactic acid and energy. Compared to fermentation, which is an aerobic respiratory process, glycolysis releases much more energy.

Thus, four ATP molecules are produced during glycolysis, whereas only two ATP molecules can be produced during fermentation.

The fermentation lacks oxidative phosphorylation, which occurs in the absence of oxygen. In contrast to glycolysis, fermentation does not allow for the Krebs cycle or the electron transport phase.

Main Differences Between Glycolysis and Fermentation

  1. Glycolysis can either be in the presence of air or in the absence of air, but fermentation takes place only in the absence of air.
  2. Glycolysis produces more energy as compared to fermentation.
  3. Glycolysis gives the end product pyruvate, whereas fermentation produces acid or alcohol and energy.
  4. The final stages of glycolysis (aerobic) occur in the mitochondria of eukaryotic cells, whereas fermentation occurs in the cytoplasm.
  5. Carbon dioxide is not produced by glycolysis, but it is produced by fermentation in plants and yeasts.

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