Difference Between Embden Meyerhof Pathway and Entner Doudoroff Pathway

The difference between Embden Meyerhof Pathway and Entner Doudoroff Pathway is that the Embden Meyerhof Pathway is the classic glycolysis that converts glucose into pyruvate in eukaryotes and many prokaryotes. At the same time, the Entner Doudoroff Pathway is an alternative pathway of glycolysis in few bacteria and converts glucose into pyruvate in order to produce ATP. 

Glycolysis is the first stage of cellular respiration,, which converts glucose into pyruvate. There are a series of reactions occurring during glycolysis. It also generates two ATP molecules as the net production. Embden Meyerhof pathway is a synonym of glycolysis. glycolysis occurs in eukaryotes and many prokaryotes, and they use glucose to generate ATP. But in certain prokaryotes, especially in certain bacteria, there is an alternative for glycolysis. This pathway is known as the Entner Doudoroff Pathway. Thus, the Entner Doudoroff pathway substitutes classic glycolysis in a few types of bacteria.

CONTENTS

1. Overview and Key Difference
2. What is Embden Meyerhof Pathway 
3. What is Entner Doudoroff Pathway
4. Similarities Between Embden Meyerhof Pathway and Entner Doudoroff Pathway
5. Side by Side Comparison – Embden Meyerhof Pathway vs Entner Doudoroff Pathway in Tabular Form
6. Summary

What is Embden Meyerhof Pathway?

Glycolysis or the Embden Meyerhof Pathway is the first step of energy production. It takes place in the cytosol of both aerobes and anaerobes. It is a series of enzyme-catalyzed reactions. In fact, it consists of ten reactions. In glycolysis, glucose molecules are phosphorylated and trapped in the cell to catabolize into pyruvate molecules. Therefore, pyruvate is the end product of glycolysis.

Glycolysis has three main stages as described below:

1. The preparatory stage – In this stage, the glucose molecule, which contains six carbon atoms, is phosphorylated and trapped in the cell. The preparatory phase is an energy-requiring phase where two ATP molecules are utilized.
2. The cleavage-stage – During this phase, the 6 – carbon molecule is cleaved into two phosphorylated 3 – carbon residues.
3. The Pay off stage – This is the final stage of glycolysis where ATP and NADH are synthesized. For each glucose molecule, 4 ATP molecules, 2 NADH molecules and 2 Pyruvate molecules are produced; thus, it is the energy-producing phase of glycolysis.

Figure 01: Embden Meyerhof Pathway

At the end of the glycolysis, as the net production, only two ATP molecules are produced from one glucose molecule.

What is Entner Doudoroff Pathway?

Entner Doudoroff pathway is an alternative pathway of glycolysis. It substitutes a classic glycolysis pathway. It takes place in only in prokaryotes, especially in few bacteria. A series of reactions occur in the Entner Doudoroff pathway and it catabolizes glucose into pyruvate.

Figure 02: Entner Doudoroff Pathway

Moreover, these bacteria utilize different enzymes in this pathway when compared to the enzymes used in classic glycolysis. Some of the enzymes used in the Entner Doudoroff pathway are 6-phosphogluconate dehydratase and 2-keto-3-deoxyphosphogluconate aldolase. Moreover, the Entner Doudoroff pathway produces a net yield of 1 ATP from each glucose molecule. It also produces only 11 NADH and 1 NADPH.

What are the Similarities Between Embden Meyerhof Pathway and Entner Doudoroff Pathway?

• Both Embden Meyerhof Pathway and Entner Doudoroff Pathway convert glucose into pyruvate in order to produce energy.
• Both processes occur in prokaryotes.
• They produce ATP and NADH.
• Moreover, both processes take place in the cytosol.
• They are enzyme-catalyzed reactions.

What is the Difference Between Embden Meyerhof Pathway and Entner Doudoroff Pathway?

Glycolysis or Embden  Meyerhof Pathway is the first step of energy production in which glucose is converted to pyruvate. On the other hand, the Entner Doudoroff Pathway is an alternative pathway of glycolysis in which glucose is catabolized into pyruvate by a few bacterial types. Therefore, this is the key difference between Embden Meyerhof Pathway and Entner Doudoroff Pathway. Embden Meyerhof Pathway has a net yield of 2 ATP while the Entner Doudoroff Pathway has a net yield of 1 ATP. This is another difference between Embden Meyerhof Pathway and Entner Doudoroff Pathway. Moreover, the Embden Meyerhof Pathway produces 2 NADH while Entner Doudoroff Pathway produces 1 NADH.

The below infographic summarizes the difference between Embden Meyerhof Pathway and Entner Doudoroff Pathway.

Summary – Embden Meyerhof Pathway vs Entner Doudoroff Pathway

Embden Meyerhof Pathway and Entner Doudoroff Pathway are two pathways which act as the initial step of energy production. Embden Meyerhof Pathway is the classic glycolysis while Entner Doudoroff Pathway is an alternative pathway of it. Both pathways produce pyruvate from glucose. But the enzymes involved are different in two pathways. The net ATP and NADH production is also different among the two pathways. Embden Meyerhof Pathway yields 2ATP and 2NADH while Entner Doudoroff Pathway yields 1ATP and 1NADH. In many living organisms, the Embden Meyerhof Pathway takes place while only in few prokaryotes, Entner Doudoroff Pathway can be seen. So, this is the summary of the difference between Embden Meyerhof Pathway and Entner Doudoroff Pathway.

Reference:

1. “Alternatives to Glycolysis.” Lumen, Available here.
2. “Glycolysis.” Wikipedia, Wikimedia Foundation, 30 Dec. 2019, Available here.

Image Courtesy:

1. “Glycolysis metabolic pathway 3 annotated” By Thomas Shafee – Own work (CC BY 4.0) via Commons Wikimedia
2. “Entner–Doudoroff pathway” By Yikrazuul – Own work; MetaCyt part I (Public Domain) via Commons Wikimedia

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