Glycolysis Important Points

Introduction

The need for an immediate supply of energy is the most essential necessity for all cells in the body. Because some cells, such as brain cells, have severely restricted glucose or ATP storage capabilities, the blood must provide a relatively consistent supply of glucose.

Glucose is delivered into cells as needed, and the energy-producing chain of reactions begins once within the cells. The three principal carbohydrate energy-producing reactions are glycolysis, the citric acid cycle, and the electron transport chain.

Table of Contents

• In Brief: Glycolysis
• An Overview of Glycolysis Pathway
• Importance of Glycolysis
• Frequently Asked Questions (FAQs)

In Brief: Glycolysis

Glycolysis is the first of cellular respiration’s key metabolic routes to generate energy in the form of ATP. The six-carbon ring of glucose is broken into two three-carbon sugars of pyruvate in two different phases through a series of enzyme reactions. The initial phase of glycolysis consumes energy, whereas the second phase accomplishes the conversion to pyruvate and provides ATP and NADH for usage by the cell.

Overall, glycolysis provides the cell with two pyruvate molecules, two ATP molecules, and two NADH molecules for energy. The glycolytic pathway is connected to the Krebs Cycle after the conversion of glucose to pyruvate, where more ATP is produced for the cell’s energy requirements. In the cytoplasm, the entire reaction of glycolysis is depicted simply as:

C₆H₁₂O₆ + 2NAD⁺ + 2ADP + 2Pi → 2 pyruvic acid, (CH₃(C=O)COOH + 2ATP + 2NADH + 2H⁺

An Overview of Glycolysis Pathway

Glycolysis can take place with or without oxygen. It is the initial stage of cellular respiration in the presence of oxygen. In the absence of oxygen, glycolysis permits cells to produce limited amounts of ATP by fermentation.

Step 1

Hexokinase phosphorylates or adds a phosphate group to glucose in the cytoplasm of a cell. The process involves transferring a phosphate group from ATP to glucose, resulting in glucose 6-phosphate, or G6P. During this phase, one molecule of ATP is used.

Step 2

Phosphoglucomutase is the enzyme that converts G6P to its isomer fructose 6-phosphate or F6P.

Step 3

To produce fructose 1,6-bisphosphate or FBP, the enzyme phosphofructokinase transfers a phosphate group to F6P using another ATP molecule. So far, two ATP molecules have been used.

Step 4

Fructose 1,6-bisphosphate is broken into a ketone and an aldehyde molecule by the enzyme aldolase. Glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) are isomers of each other.

Step 5

DHAP is readily converted to GAP by the enzyme triose-phosphate isomerase (these isomers can interconvert). The next phase of glycolysis requires GAP as a substrate.

Step 6

The enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) performs two main functions. GAP is first dehydrogenated by transferring one of its hydrogen (H+) molecules to the oxidising agent nicotinamide adenine dinucleotide (NAD+), resulting in NADH + H⁺.

GAPDH then joins the oxidised GAP with phosphate from the cytosol to generate 1,3-bisphosphoglycerate (BPG). This process of dehydrogenation and phosphorylation is carried out on both molecules of GAP generated in the previous step.

Step 7

Phosphoglycerokinase is an enzyme that moves a phosphate from BPG to a molecule of ADP to generate ATP. This happens to each and every BPG molecule. Two 3-phosphoglycerate (3 PGA) molecules and two ATP molecules are produced in this process.

Step 8

The enzyme phosphoglyceromutase moves the phosphate group from the third to the second carbon of two 3-PGA molecules, resulting in two 2-phosphoglycerate (2 PGA) molecules.

Step 9

To make phosphoenolpyruvate (PEP), the enzyme enolase extracts a molecule of water from 2-phosphoglycerate. This occurs for each of the 2 PGA molecules generated in Step 8.

Step 10

Pyruvate kinase is the enzyme that transfers a phosphate group from PEP to ADP to produce pyruvate and ATP. This occurs for each PEP molecule. This process generates two pyruvate molecules and two ATP molecules.

Importance of Glycolysis

• Glycolysis is a process that occurs in almost all living things.
• Cells get almost all of their energy from glucose.
• Glycolysis leads to the production of two pyruvate molecules, two ATP molecules, and two NADH molecules.
• It is found in both prokaryotes and eukaryotes, and it is used in aerobic and anaerobic respiration.
• Because glycolysis takes place in the cytosol, it is a key source of energy for species that lack mitochondria.
• Lactate and ethanol fermentation, transamination to generate alanine, glycogen metabolism, the pentose phosphate pathway, and other activities are interconnected via glycolysis.
• When muscles have a high energy demand and a lack of oxygen, the anaerobic glycolysis pathway is utilised to produce energy.
• Pyruvate, the end product of glycolysis, is an intermediate in several other processes, including gluconeogenesis, fermentation, fatty acid production, etc.
• Even glycolysis intermediates are employed in other metabolic pathways; for example, DHAP (dihydroxyacetone phosphate) is converted to glycerol 3-phosphate, used in triglyceride synthesis.

Read Also:

• Significance of Glycolysis
• Glycolysis: An Introduction To Glycolytic Pathway
• What Are the Two Phases of Glycolysis Called?
• What Is the Starting Material for Glycolysis?
• What Is The Purpose Of Glycolysis And Cellular Respiration?
• How Are Glycolysis and the TCA Cycle Linked?