Understanding Glycolysis Process and Steps

Aug 6, 2024

Glycolysis Overview

Definition

  • Glycolysis: Derived from two words:
    • Glyco: Means glucose
    • Lysis: Means breakdown
  • Purpose: Metabolic pathway for systematic breakdown of glucose to produce energy.

Location

  • Takes place in the cytosol of the cells.

Process Overview

  • One molecule of glucose (6 carbon compound) is broken down into two molecules of pyruvate (3 carbon compound).
  • Energy is released in the form of ATP and NADH.
  • Pyruvate is utilized in various energy-producing pathways.

Phases of Glycolysis

  1. First Phase: Energy Utilization
    • Glucose is converted into two molecules of glyceraldehyde 3-phosphate (G3P).
    • This phase uses energy instead of producing it.
  2. Second Phase: Energy Production
    • G3P is converted into pyruvate and energy is produced.

Reactions Involved in Glycolysis

  1. Conversion of Glucose to Glucose 6-Phosphate

    • Enzyme: Hexokinase
    • ATP → ADP (utilizes 1 ATP)

  2. Conversion of Glucose 6-Phosphate to Fructose 6-Phosphate

    • Enzyme: Isomerase
    • Simple rearrangement.

  3. Conversion of Fructose 6-Phosphate to Fructose 1,6-Bisphosphate

    • Enzyme: Phosphofructokinase
    • ATP → ADP (utilizes 1 ATP)

  4. Splitting of Fructose 1,6-Bisphosphate

    • Enzyme: Aldolase
    • Produces: G3P and dihydroxyacetone phosphate (DHAP)

  5. Conversion of G3P to 1,3-Bisphosphoglycerate

    • Enzyme: Glyceraldehyde 3-Phosphate Dehydrogenase
    • NAD+ → NADH (reduction) and utilizes inorganic phosphate.

  6. Conversion of 1,3-Bisphosphoglycerate to 3-Phosphoglycerate

    • Enzyme: Phosphoglycerate Kinase
    • Transfers phosphate to ADP, generating ATP.

  7. Conversion of 3-Phosphoglycerate to 2-Phosphoglycerate

    • Enzyme: Phosphoglycerate Mutase

  8. Conversion of 2-Phosphoglycerate to Phosphoenolpyruvate

    • Enzyme: Enolase
    • Requires magnesium ions.

  9. Conversion of Phosphoenolpyruvate to Pyruvate

    • Enzyme: Pyruvate Kinase
    • Transfers phosphate to ADP, generating ATP.

Summary of ATP Utilization and Production

  • Net Reaction of Glycolysis:
    • 1 molecule of glucose (6 carbons) splits into 2 molecules of pyruvate (3 carbons each).
  • ATP Summary:
    • 2 ATP used in the first phase.
    • 4 ATP generated in the second phase.
    • Net Gain: 2 ATP (due to 2 ATP used).
  • NADH Production: 2 molecules of NADH produced.

Conclusion

  • Glycolysis is an essential metabolic pathway for energy production from glucose.
  • Watch for more detailed videos and flashcards on related topics.