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Glycolysis

Glycolysis

A fundamental metabolic pathway that breaks down glucose into pyruvate while generating ATP and NADH.

Glycolysis

Glycolysis (from Greek: "glyco-" meaning sweet, and "-lysis" meaning splitting) is a universal and ancient metabolic pathway that converts one molecule of glucose into two molecules of pyruvate, while generating energy in the form of ATP and reducing power as NADH.

Process Overview

The pathway consists of ten enzymatic steps, divided into two major phases:

  1. Investment Phase (Steps 1-5)

    • Consumes 2 ATP molecules
    • Converts glucose to fructose-1,6-bisphosphate
    • Creates unstable high-energy intermediates

  2. Payoff Phase (Steps 6-10)

    • Generates 4 ATP molecules
    • Produces 2 NADH molecules
    • Forms 2 pyruvate molecules

Key Features

  • Net Energy Production

    • Net gain of 2 ATP molecules
    • Generation of 2 NADH molecules
    • Creation of metabolic intermediates for other pathways

  • Universal Nature

Regulation

Glycolysis is tightly regulated through several mechanisms:

  1. Allosteric Regulation

  2. Hormonal Control

Clinical Significance

Disruptions in glycolysis are associated with several pathological conditions:

  • cancer cells often show increased glycolytic activity (Warburg effect)
  • genetic disorders affecting glycolytic enzymes
  • diabetes impacts glucose utilization

Evolutionary Significance

Glycolysis likely evolved before oxygen became abundant on Earth, making it one of the oldest known metabolic pathways. Its universal presence across life forms suggests its emergence in the last universal common ancestor.

Industrial Applications

The pathway has significant applications in:

Interconnections

Glycolysis serves as a central hub in cellular metabolism, connecting to: