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Understanding Cellular Respiration: Processes, Stages, and Efficiency

Cellular respiration is a catabolic process that consumes oxygen and sugars to produce carbon dioxide, water, and ATP. It involves oxidation and reduction reactions, resulting in a change in free energy of -686 kcal/mol. The main stages include glycolysis (occurring in the cytosol), the citric acid cycle (in the mitochondrial matrix), and oxidative phosphorylation (in the inner mitochondrial membrane). These processes enable the efficient breakdown of glucose and the synthesis of ATP, effectively using energy while minimizing losses.

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Understanding Cellular Respiration: Processes, Stages, and Efficiency

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  1. Cell Respiration

  2. Cell Respiration • Cell Respiration: catabolic process • Consume Oxygen and Sugars • Creates Carbon Dioxide, Water, and ATP • Change in G(Free energy)= -686 kcal/mol • Combination of oxidation and reduction reactions • Oxidations: Loss of electrons • Reduction: Addition of electrons (reduce or make more negative charge)

  3. Cell Respiration

  4. Cell Respiration

  5. Cell Respiration • Sugars are good fuel because their electrons want to move • Oxidation and reduction happens easily • Little activation energy required • BUT Sugars need to be broken down part by part • This is more energy efficient • Hydrogens are moved to Oxygen after being passed to a coenzyme NAD+ (Oxidizing agent.) • H + NAD+ NADH (Neutral)

  6. Cell Respiration

  7. Cell Respiration • Electron Transport Chain: breaks the fall of electrons to oxygen into several steps. • Controls energy release • Reduces lost energy in the process • Occurs in INNER MEMBRANE of mitochondria • Movement of electrons in Cell Respiration • Food  NADH  Electron Transport Chain  Oxygen

  8. Cell Respiration • Stages of cell respiration • Glycolysis • Citric Acid • Oxidative Phosphorylation

  9. Cell Respiration • Glycolysis • Occurs in Cytosol/Cytoplasm outside of Mitchondria • Breaks down glucose into pyruvate • Citric Acid Cycle • Occurs in mitochondrial matrix • Oxidizing broken down pyruvate to Carbon Dioxide • Both involve reduction with NAD+ • Oxidative Phosphorylation • Inner Membrane of Mitochondria • ATP Synthesis • Through reduction/oxidation reactions

  10. Cell Respiration • Glycolysis: “Splitting of sugar” • Glucose  2 Pyruvate + 2H2O • + 4 ATP, - 2 ATP • 2 NAD+ + 4 e- + 4 H+  2 NADH + 2 H+ • Breaks the ring glucose into 2 straight sugars • Each straight sugar is transformed by enzymes to be pyruvate • Release 25% of the energy in glucose

  11. Cell Respiration

  12. Cell Respiration • Citric Acid Cycle: • Pyruvate enters mitochondria through ACTIVE TRANSPORT • NAD+ NADH • Pyruvate converted to Acetyl CoA • Process supported by an enzyme at each step • Overall • 3NAD+ NADH • FAD+  FADH2 • 2C2O • 1 ATP (Through GTP)

  13. Cell Respiration

  14. Cell Respiration • Oxidative Phosphorylation • Combines the electron transport chain with chemiosmosis • Example of ENERGY COUPLING AND CO TRANSPORT • Electrons are added to electron transport chain from • NADH • FADH2 • Cytochromes • ELECTRON TRANSPORT CHAIN MAKES NO ATP DIRECTLY • BUT HELPS IT INDIRECTLY

  15. Cell Respiration • Chemiosmosis: Creating a membrane potential by removing H+ out of the Mitochondria ACTIVELY and then using its return to drive the synthesis of ATP • Mitochondria pumps Hydrogen Ions out with Electron Transport Chain • Electron transport chain is a series of integral proteins in the INNER MEMBRANE of the mitochondria • Once hydrogen ions are pumped out, membrane potential is created so the hydrogen ions want to diffuse back inside the Mitochondria. • The Hydrogen moves through another integral protein ATP SYNTHASE • ATP Synthase makes ATP as Hydrogen moves through it.

  16. Cell Respiration

  17. Cell Respiration • Overall Cell Respiration: • Change in G = -686 kcal/mol • 36-38 ATP Created • 7.3 kcal/mole to make ATP • 7.3 x 38/686 =0.4 • 40% efficiency for transferring energy • The rest is lost in heat

  18. Cell Respiration

  19. Cell Respiration • Aerobic: Respiration with oxygen • Anaerobic: Respiration without oxygen • Fermentation: Glycolysis which transfers electrons to Pyruvate so that they can be used again for another cycle glycolysis • Two Types of Fermentation: • Alcohol: Pyruvate converted to ethanol • Bacteria/yeast both do this • Creates beer • Lactic Acid: pyruvate converted to lactate • No CO2 created

  20. Cell Respiration

  21. Cell Respiration

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