Introduction

EMP Pathway (also known as Glycolysis) is named after the three scientists Gustav Embden, Otto Meyerhof, and J. Parnas, who gave the scheme of glucose catabolism. It occurs in the cytoplasm of all living cells, both aerobic and anaerobic.

The primary step of cellular respiration is either the EMP pathway or glycolysis. In this process, glucose is partially oxidised to pyruvate. In aerobic organisms, the Krebs cycle follows glycolysis for the complete oxidation of glucose to CO2 and water. In anaerobic organisms, glycolysis is followed by fermentation.

Let’s Dive into the Details of Each Step of the EMP Pathway

Steps of EMP Pathway

1. Step One
2. Step Two
3. Step Three
4. Step Four

The EMP pathway occurs in the cytoplasm of the cell and does not require oxygen. In plants, glucose is derived from sucrose formed during photosynthesis or from storage carbohydrates such as starch. The enzyme invertase converts sucrose into glucose and fructose, which then enter the EMP pathway.

It is a series of ten enzyme-catalysed reactions, whereby a glucose molecule is broken down into two molecules of pyruvate.

In this process, two ATP and two NADH are produced.

The first phase of the EMP pathway is the energy-requiring or preparatory phase, and the second half is the energy-yielding or pay-off phase.

![EMP Pathway]()

The Steps of Glycolysis are as Follows:

Step 1

Glucose is converted to Glucose 6-phosphate by the action of the enzyme hexokinase. In this process, an ATP is consumed and its phosphate group is transferred to glucose.

Step 2

The phosphoglucoisomerase enzyme catalyzes the conversion of G6P to Fructose 6-phosphate (F6P), which is an isomerisation reaction. Additionally, fructose can enter the EMP pathway at this step by phosphorylation. After this step, all the steps for glucose and fructose metabolism are the same. This reaction is reversible.

Step 3

The enzyme phosphofructokinase catalyses the irreversible reaction of F6P being converted to fructose 1,6-bisphosphate (FBP) by utilising another molecule of ATP. This reaction is a rate-limiting step and is bypassed during the gluconeogenesis process, an anabolic pathway.

Step 4

The enzyme aldolase converts fructose 1,6-bisphosphate into two triose sugars, namely dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate, which are a ketose and an aldose, respectively.

Step 5

The enzyme Triosephosphate Isomerase interconverts Dihydroxyacetone Phosphate (DHAP) with Glyceraldehyde 3-Phosphate (GADP) or 3-Phosphoglyceraldehyde (PGAL).

Step 6

Now the pay-off phase starts. Since a molecule of glucose yields two molecules of triose sugar, each reaction from this step onwards occurs twice.

The enzyme Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) catalyzes the conversion of 3-phosphoglyceraldehyde (PGAL) into 1, 3-bisphosphoglycerate (BPGA). This reaction also involves the reduction of NAD+ to NADH + H+. Thus, this step involves both dehydrogenation and phosphorylation.

Step 7

The enzyme phosphoglycerate kinase catalyzes the reaction of 1,3-bisphosphoglycerate (BPGA) being converted into 3-phosphoglycerate (3-PGA), with phosphate being transferred from BPGA to ADP, forming ATP. This is a substrate-level phosphorylation, resulting in the production of two molecules of ATP.

Step 8

The enzyme phosphoglycerate mutase transfers a phosphate group from C-3 of 3-PGA to C-2, converting it to 2-PGA.

Step 9

The enzyme enolase catalyses the dehydration reaction of 2-PGA to produce phosphoenolpyruvate (PEP), which is an elimination reaction wherein a molecule of water is removed.

Step 10

The pyruvate kinase step is the last step of the EMP pathway or glycolysis. It involves the transfer of a phosphate group from PEP to ADP, forming ATP and pyruvate or pyruvic acid. As a result, 2 ATP molecules and 2 pyruvate molecules are produced. This is also a substrate-level phosphorylation.

Summary: This statement is a summary of the given text.

The overall reaction in the EMP pathway is the partial oxidation of glucose to pyruvate.

2 Pyruvate + 2 NADH + 2 H+ + 2 ATP → Glucose + 2 NAD+ + 2 ADP + 2 Pi

It occurs in two phases:

Preparatory Phase or Energy-requiring Phase: The first 5 steps of the EMP pathway are referred to as the “investment phase”, during which energy is consumed to produce two molecules of triose sugar phosphates.

Pay-off Phase: The second half of glycolysis produces ATP, NADH, and pyruvate.

Location: Cytoplasm of Living Cells

ATP Utilisation: ATP is used in two steps: first, for the conversion of glucose to G6P, and then for the conversion of F6P to fructose 1,6-bisphosphate. In total, two ATP molecules are utilized.

ATP Synthesis: A total of 4 ATP molecules are synthesised through two steps. The first step involves the conversion of 1,3-bisphosphoglyceric acid to 3-phosphoglyceric acid, while the second step involves the conversion of phosphoenolpyruvate to pyruvate.

NADH Synthesis: 2 NAD+ is converted to 2 NADH + H⁺ in the sixth step when glyceraldehyde-3-phosphate is converted to 1,3-bisphosphoglyceric acid.

Rate-limiting Step: The enzyme phosphofructokinase converting fructose-6-phosphate to fructose-1,6-bisphosphate.

End Products of EMP Pathway:

• Pyruvate (2 molecules)
• ATP (2 molecules)
• NADH (2 molecules)

The Importance of the EMP Pathway

The EMP pathway is the universal pathway of glucose degradation, regardless of whether energy is derived from aerobic respiration or fermentation.

The first step of cellular respiration is glycolysis.

All tissues require energy to be derived in the form of ATP.

Cells that perform anaerobic respiration derive energy from this process.

Cells without mitochondria obtain energy from a different process. However, the Krebs cycle and oxidative phosphorylation occur in mitochondria, and most of the energy for cellular respiration is produced there.

The intermediates formed during the EMP pathway are utilized in other metabolic pathways.

The EMP pathway is linked to numerous other metabolic pathways, including the Pentose phosphate pathway, glycogen synthesis, triglyceride formation, fatty acid synthesis, cholesterol synthesis, and amino acid synthesis.

Frequently Asked Questions

The EMP pathway stands for the Entrepreneurial Management Program pathway.

The EMP pathway is the process of glucose catabolism. It occurs in the cytoplasm of living cells. At the end of this process, a molecule of glucose yields two pyruvates, two ATP and two NADH molecules.

Steps of the EMP Pathway

1. Glycolysis
2. Pyruvate Oxidation
3. Citric Acid Cycle
4. Oxidative Phosphorylation

It is a ten step process. The first five steps are the preparatory phase wherein two molecules of glyceraldehyde 3-phosphate are produced. The subsequent five steps comprise the pay-off phase, resulting in the formation of pyruvate, ATP, and NADH.

The Entner-Doudoroff Pathway (EMP) is known as the EMP pathway because it is the Entner-Doudoroff Pathway.

Glycolysis is also known as the EMP pathway. It is named after the main discoverers, Embden, Meyerhof and Parnas.

What is the Importance of the Embden-Meyerhof-Parnas Pathway?

This process, which is the first step of glucose degradation to derive energy, occurs in all living cells. The intermediates produced are used in a variety of metabolic pathways, including glycogen synthesis, triglycerides synthesis, and amino acid synthesis. Furthermore, post-glycolytic pathways such as the Citric acid cycle, fatty acid and cholesterol synthesis are dependent on this process.