Cell Metabolism: Glycolysis and the TCA Cycle

Why is Metabolism Important?

1. Energy is required for:

• Motion (muscle contraction)

• Transport (of ions/molecules across membranes)

• Biosynthesis of essential metabolites

• Thermoregulation

2. Timing of these processes does not necessarily coincide with feeding times so storage forms of food are required

What is ATP?

•ATP (adenosine triphosphate) provides most of the energy required

•ATP is the energy currency of the cell

What is the Structure of ATP?

What is Metabolism?

Metabolism: integrated set of enzymatic reactions comprising both anabolic and catabolic reactions

What is Anabolism?

Anabolism: synthesis of complex molecules from simpler ones (necessary energy usually derived from ATP)

What is Catabolism?

1. Catabolism: breakdown of energy- rich molecules to simpler ones (CO₂  H₂O  and  NH₃)

2. (energy released is ‘captured’ as ATP and stored for later use in anabolic reactions

What is the Structure of Mitochondria?

Cellular Energy Metabolism

Cofactors, Coenzymes and Prosthetic Groups

The Redox Coenzymes/Prosthetic Groups

Re-oxidation of Redox Coenzymes

1. Re-oxidation (recycling) of NADH and FADH₂ is via the respiratory chain in the mitochondria

2. This is coupled to ATP synthesis - process of oxidative phosphorylation

3. ~ 2.5 molecules of ATP synthesised for each NADH re-oxidised 

4. ~ 1.5  molecules of ATP synthesised for each FADH₂ re-oxidised 

Glycolysis- Priming Stages

Glycolysis- Payoff Reactions

Summary of Glycolysis

What are the Products of Glycolysis?

How do Electrons from NADH enter Mitochondria?

What is the Glycerol-3-Phosphate Shuttle?

What is the Malate-Aspartate Shuttle

What is the Role of Pyruvate in Metabolism?

What are the Possible Fates of Pyruvate?

What happens to Pyruvate under Aerobic Conditions?

How is Pyruvate Transported into the Mitochondria?

What is the Tricarboxylic Acid Cycle (TCA)?

8 Intermediates of the TCA Cycle

9 Enzymatic Steps in the TCA Cycle

What are the Regulatory Points of the TCA Cycle?

What are the Products of the TCA Cycle?

Components of the TCA cycle are important biosynthetic intermediates

Summary

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