Cellular Respiration

• Cellular Respiration


  The breakdown of glucose in many small steps to make ATP

  
• Cellular Respiration


  • Breakdown of a "large sugar" molecules into smaller ones
  • Breaking bonds and moving electrons from one molecule to another
  • Electrons "carry energy"
  • Energy is used to make ATP

  
• Cellular Respiration: Glucose + Oxygen -> Carbon dioxide + Water + Energy

  
• Oxidation


  The loss of electrons by a molecule, atom, or ion
• Reduction


  The gain of electrons by a molecule, atom, or ion
• In a redox reaction, glucose is oxidised and oxygen is reduced

  
• Electron carriers


  Molecules that are particularly effective in accepting or donating high energy electrons
• NAD+


  Nicotinamide Adenine dinucleotide, an oxidised coenzyme that can accept two electrons and two hydrogen atoms to be reduced to NADH

  
• FAD


  Flavin Adenine dinucleotide, an oxidised cofactor that can accept two hydrogen atoms and two electrons to be reduced to FADH2
• NADH and FADH2 contain high energy electrons that can be used to make ATP in the electron transport chain
• ATP


  Adenosine Tri-Phosphate, the universal currency of free energy in biological systems
• Hydrolysis of ATP


  1. ADP + Pi

  2. Releases energy
• ATP hydrolysis is favourable as the reactant has more energy than the product, free energy is released, and the product is more stable
• ATP is structurally unstable due to the repulsion between ionised oxygen atoms</b>
• ATP is hydrolysed by the enzyme ATPase
• Stages of cellular respiration

  • Glycolysis
  • Pyruvate processing
  • Citric Acid Cycle (Krebs Cycle)
  • Electron transport chain

  
• Glycolysis


  • Uses glucose as a starting material
  • Converts glucose to pyruvate
  • Involves 10 chemical reactions controlled by enzymes

  
• The final product of glycolysis is passed on to the next stage of respiration
• ATPADPAMP


  Abbreviation for Anatomy, Physiology, Pharmacology And Microbiology
• PHA112


  Course code
• Cellular Respiration


  1. Glycolysis

  2. Pyruvate processing

  3. Citric Acid Cycle (Krebs Cycle)

  4. Electron transport chain

  
• Glycolysis uses GLUCOSE from our diet as a starting material

  
• Glucose is converted to a chemical called PYRUVATE

  
• Glycolysis has 10 chemical reactions all controlled by enzymes
• Preparatory/investment phase


  Stage 1 of glycolysis, uses ATP
• Payoff phase


  Stage 2 of glycolysis, makes ATP and NADH
• Stage 1 of Glycolysis

  Isomers
• Second Phase Of Glycolysis

  1. DHAP converted to G3P hence 2xG3P

  2. Substrate level phosphorylation: Make ATP by transferring phosphate from a substrate
• PEP converted to pyruvate, phosphate group returned back to ADP to make ATP
• Glycolysis


  • Converts glucose to pyruvate
  • 2 NADH are produced by reduction of NAD+
  • NET production of 2 ATP molecules by substrate level phosphorylation
  • 2 molecules of pyruvate are produced
  • Occurs in the cytoplasm

  
• Sugars that can be bound together

  • Glycogen
  • Starch

  
• Feeder Pathway For Glycolysis

  Entry of glycogen, starch, disaccharide's into the preparatory stage of glycolysis

  
• Lactose intolerance


  Lack or lower level of the enzyme "lactase" means lactose remains undigested, leading to gas, bloating, pain and diarrhoea as gut bacteria ferment the undigested lactose

  
• NAD+ Regeneration


  For glycolysis to continue NADH must be recycled back to NAD+
• Types of respiration


  • Aerobic respiration
  • Anaerobic respiration (or fermentation)
• In The Absence Of Oxygen - Anaerobic Respiration Occurs


  1. Pyruvate is reduced to form Lactic acid / Lactate

  2. Transferred electrons oxidise NADH back to NAD+

  3. Reaction catalysed by Lactate dehydrogenase (LDH)

  4. Lactic acid converted back into glucose in the liver via the Cori cycle

  
• Cori Cycle (Lactic Acid Cycle)

  Lactate produced during anaerobic glycolysis is transported to the liver and converted to glucose, which is then supplied back to the muscle

  
• The Heart and Brain cannot be starved of fuel, so pyruvate can be converted back to glucose via a process called Gluconeogenesis, which occurs in the liver
• Oxidation of Pyruvate


  In the presence of oxygen, pyruvate is oxidised to acetyl CoA in the mitochondria
• Acetyl CoA Then Enters - The Citric Acid Cycle

  1. Glycolysis produces Pyruvate

  2. Pyruvate is converted to Acetyl CoA

  3. Acetyl CoA now progresses to the Citric Acid Cycle