ATP Synthesis

Introduction

• ATP (adenosine triphosphate) is the primary energy currency of cells, essential for various cellular processes.
• The synthesis of ATP is a crucial aspect of cellular respiration, where energy is generated from organic molecules.

Respiration Pathway

• Cellular respiration is a metabolic pathway responsible for ATP synthesis.
• It involves the breakdown of organic molecules, with glucose being the primary substrate.

Three Main Stages of Respiration

1. Glycolysis

• Location: Occurs in the cytoplasm.
• Initial stage of respiration.
• Glucose is partially broken down into pyruvate.
• Generates a small amount of ATP and NADH (a molecule that carries high-energy electrons).

2. Citric Acid Cycle (Krebs Cycle)

• Location: Occurs in the matrix of the mitochondria.
• Pyruvate from glycolysis enters the mitochondria.
• Further breakdown of pyruvate occurs.
• Produces NADH and FADH2 (another electron carrier).
• Carbon dioxide is released as a waste product.

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ATP Synthesis

3. Electron Transport Chain (ETC)

• Location: Occurs in the inner membrane of the mitochondria.
• NADH and FADH2 from earlier stages transfer high-energy electrons to the ETC.
• These electrons move through a series of protein complexes.
• As electrons pass through these complexes, protons are pumped across the inner mitochondrial membrane, creating a proton gradient.
• The flow of protons back through ATP synthase enzyme drives ATP synthesis.
• Oxygen is the final electron acceptor, combining with electrons and protons to form water.

ATP Synthesis in ETC

• The flow of protons (H+) back into the mitochondrial matrix through ATP synthase powers the synthesis of ATP.
• ATP synthase acts like a molecular turbine, converting the energy of proton movement into the formation of ATP from ADP and inorganic phosphate (Pi).