Cell Respiration

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Cell Respiration
Chapter 9
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Why Respire?

• Living cells require energy transfusions to
  perform most of their tasks
• From external sources
• Assembling polymers
• (what is the general reaction called?)
• Pumping substances across their gradient
• (what is the generic reference for this process?
  Where did we see this in Lab 1?)
• Moving

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Notes on Previous Slide

• Energy flows into an ecosystem as sunlight
• Leaves as heat
• Why cant energy just be created?
• Which Law of Thermodynamics helps explain this
  flow?
• Essential chemical elements of life are recycled
• Photosynthesis (plants) make Oxygen and Sugars
• Cellular respiration take oxygen and sugars, make
  CO2 and H2O energy
• The products of respiration (CO2 and H2O) are the
  raw materials of photosynthesis

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Cellular Respiration

• Cellular respiration is catabolic
• Catabolic processes are exergonic
• Energy release from glucose is used to
  phosphorylate ADP ? ATP
• So cellular respiration burns fuels and uses the
  energy to regenerate ATP
• Life processes constantly consume ATP

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Respiration Overall

• Food ? Glucose ? NADH ? ATP
• Glycolysis ? Pyruvate Oxidation ? Krebs
  Cycle ? Oxidative Phosphorylation
• Cytoplasm ? Mitochondrion ? Matrix ? Inner
  Mitochondrial Membrane

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2 Respiration Pathways

• Cell Respiration
• Called Aerobic Respiration
• Requires Oxygen
• Generates 36 or 38 ATP per glucose
• Fermentation
• Called Anaerobic Respiration
• Oxygen NOT needed
• Ethanol or Lactic Acid forms
• Generates 2 ATP per glucose

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3 Stages of Respiration

• Glycolysis
• Decomposes glucose
• 6-Carbon to 2 (3-Carbon molecules)
• Occurs in cytosol
• Citric Acid Cycle
• Continues decomposing 2-Carbon into CO2
• Mitochondrial matrix
• Oxidative Phosphorylation
• ETC Chemiosmosis
• Powered by redox rxns
• Method of ATP synthesis
• Across inner mitochondrial membrane

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Cellular Respiration
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Questions

• Is respiration exergonic or endergonic? Why?
• Is fermentation exergonic or endergonic? Why?
• Does respiration require enzymes?
• What are the 2 catabolic pathways?
• How do they differ?

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Questions (Page 2)

• What are the 4 parts of cellular respiration?
• Which of the parts produce ATP?
• Which of the parts produce NADH?
• Which part(s) of cellular respiration require
  oxygen?

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Glycolysis

• Splitting of glucose
• Cytosol (cytoplasm)
• 6-Carbon molecule ? 2 (3-Carbon molecules)
• 2 Phases
• Energy Investment (Consumes 2 ATP)
• Energy Payoff (Produces 4 ATP)

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Pyruvate Oxidation

• Pyruvate ? Acetyl CoA
• 3-Carbon ? 2-Carbon
• Needs to get into the mitochondrion
• Transport protein
• Produces
• NADH or FADH2
• CO2

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Citric Acid Cycle

• Called Krebs Cycle OR TricarboxylicAcic Cycle
  (TCA)
• Mitochondria
• Produces
• CO2
• NADH
• FADH2
• ATP (Actually GTP ? ATP)

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Questions

• What is Glycolysis?
• What is produced in Glycolysis?
• Where does Glycolysis occur in a eukaryotic cell?
• Where does it occur in a prokaryotic cell?

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Oxidative Phosphorylation

• 2 Parts
• Electron Transport Chain
• Chemiosmosis
• Electron Transport Chain
• Embedded in inner mitochondrial membrane
• Pumps Protons out of the matrix into the
  intermembrane space
• Establishes electrochemical gradient
• Chemiosmosis
• ATP Synthase makes ATP

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A Different Perspective

• Glycolysis Citric Acid Cycle
• Redox rxns
• Decompose glucose into CO2
• Transfers electrons from Glucose to NAD (NADH is
  formed)
• Oxidative Phosphorylation
• Accepts electrons from NADH and uses them to
  drive ATP synthesis
• Series of steps
• O2 is the final electron acceptor, forms H2O

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Questions

• What are the 4 Parts of Cellular Respiration?
• What is the purpose of Pyruvate Oxidation?
• What is produced in Pyruvate Oxidation?
• For each glucose, how many pyruvate oxidations
  occur?

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Questions (Page 2)

• Where does the TCA cycle occur in a eukaryotic
  cell?
• Where does it occur in a prokaryotic cell?
• What are the 2 alternate names for the TCA cycle?

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Questions (Page 3)

• For each glucose, how many turns of the TCA cycle
  occur?
• Each turn of the TCA cycle produces how much
• CO2?
• ATP?
• NADH?
• FADH2?

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Fermentation

• 2 Forms
• Lactic Acid fermentation (2 ATP)
• Alcoholic fermentation (2 ATP 2 CO2)
• Glycolysis 1 extra step (Recycles NAD)
• Does NOT require oxygen

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Fermentation

• Lactic Acid Fermentation
• 3-Carbon ? 3-Carbon
• 3-carbon Lactate or Lactic acid (What
  functional group?)
• Muscles
• Alcoholic Fermentation
• 3-Carbon ? 2-Carbon
• 2-Carbon Ethanol (What functional group?)
• CO2
• Beer or wine

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