Recording-2025-03-10T18:28:13.532Z

Test Preparation

• Scheduled test to take place during lecture.

• Equation sheets were distributed previously; students needing one can get it.

Course Structure

• Discussion of upcoming tests and labs:

  • Tests will take place soon.

  • Three labs remaining before the course concludes.

  • The lab test will be scheduled for April.

Metabolic Pathways Overview

• Introduction to metabolic pathways, with emphasis on understanding:

  • Reactants

  • Enzymes

  • Products

• Importance of knowing cycles for exam success.

Anaerobic ATP Production Pathways

• Location: Anaerobic ATP production pathway occurs in the sarcoplasm of the cell.

• Discussion of intermediates:

  • Intermediates refer to any reactant or product in a metabolic pathway.

  • Not to be confused with enzymes.

Key Steps in Anaerobic ATP Production

• ATP Breakdown:

  • Initial breakdown of ATP occurs via myosin ATPase.

  • Products:

    • ADP (adenosine diphosphate)

    • Inorganic phosphate

    • Energy produced from ATP breakdown.

  • Second step:

    • Involves phosphocreatine (PC) and ADP, acted upon by creatine kinase (CK), leading to ATP production.

• Emphasis on: Understanding the three enzymatic reactions for maintaining high-intensity exercise.

Anaerobic Glycolysis

• Process: Anaerobic Glycolysis

  • Takes place in the sarcoplasm and produces ATP under anaerobic conditions.

  • End product is lactate, relevant in the accumulation hypothesis related to fatigue during exercise.

  • Primarily responsible for ATP production during activities like 400m or 800m sprints.

Glucose Utilization

• Sources of glucose for glycolysis include:

  • Blood glucose from circulation

  • Glycogen stores in the liver and muscle fibers.

• Phosphorylation of glucose to glucose six phosphate (G6P):

  • Enzyme: Hexokinase (HK)

  • Each phosphorylation consumes 1 ATP, resulting in a net energy cost.

  • Once phosphorylated, glucose is committed to that muscle fiber (not shareable).

Glycolysis Steps

• Key steps and ATP accounting:

  • From any glucose entering, one ATP is used in the HK step, and again in the phosphofructokinase (PFK) step, totaling -2 ATP net.

  • Gross ATP production remains at zero until later steps of glycolysis.

• Aldolase Reaction:

  • Six-carbon fructose-1,6-bisphosphate splits into two three-carbon molecules (DHAP and glyceraldehyde).

Oxidation-Reduction Reactions in Glycolysis

• Importance of coupled reactions in glycolysis:

  • When one substance is reduced (by gaining hydrogen), another substance is oxidized.

• Hydrolysis and oxidation reductions are crucial metabolic processes in ATP production.

Summary and Preparation Tips

• Students are encouraged to bring relevant metabolic pathways resources to class for visualization.

• Familiarity with glucolytic pathways and associated costs is essential for exam success.

• Ensure understanding of all enzymatic steps and intermediates throughout glycolysis.