Cellular Respiration and Fermentation

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Cellular Respiration and Fermentation

• Chapter 9 (M)

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Living is work

• Cells require energy from outside sources to
  perform work
• Ecosystems?energy enters as sunlight.
• Light energy trapped in organic molecules is
  available to both photosynthetic organisms and
  others that eat them

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Chemical Energy and Food

• Food Stores Chemical Energy
• Carbohydrates, fats, proteins from food do not
  drive work in cells directly
• The chemical energy stored in these must be
  converted into a more usable form
• ATP ? Energy Molecule

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Food as Fuel

• Carbohydrates, fats and proteins are all used to
  generate ATP
• Fats?9 Calories/gm,
• Proteins and Carbs? 4Calories/gm
• 1 Calorie (kilocalorie) 1000 calories
• Basic Calorie need? 2200 for female teens, 2500
  males

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Energy in Food

• Not released at once, if so cant be harnessed
• Broken down in a series of steps and electrons
  are carried? final acceptor is O2

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• High Energy
• Food? Energy Released? Stored in ATP

ATP
ATP
ATP
Low Energy Waste
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Cellular Respiration Breathing

• Respiration Breathing
• Respiration ? exchange of gases
• Organisms? O2 from env.? gives off CO2

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Cellular Respiration Breathing

• To a biologist Respiration? the aerobic
  harvesting of energy from food ? Cellular
  Respiration
• Breathing Cellular Respiration are very closely
  related
• CR ? main function is to harvest energy from food

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• O2? Lungs ?Blood Stream? muscles? mitochondria
  use O2 in CR? energy for muscles to work?CO2?
  blood ?lungs ?out

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General Equation

• C6H12O6 6O2? 6CO2 6H2O ATP
• Energy stored in chemical bonds of ATP

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CR Harvests energy by rearranging electrons

• CR ? rearranges the electrons in the chemical
  bonds in glucose
• Glucose is broken down in a series of steps
• Electrons are removed, energy released is stored
  in ATP
• Electrons lost from glucose end up in the H-atoms
  of H20

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Two main groups of reactions

1. Glycolysis (anaerobic respiration)?energy
   investment
2. Aerobic Respiration? energy payoff

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Glycolysis

• Anaerobic respiration
• takes place in the cytoplasm of the cell
• Glucose is broken down into pyruvic acid

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Aerobic Respiration

• Takes place in the mitochondria of cells in two
  stages
• Krebs Cycle ? matrix of the mitochondria
• Electron transport chain ?membrane of the
  mitochondria

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Figure 9.6 An overview of cellular respiration
(Layer 1)
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Krebs Cycle

• Takes place in the matrix of the mitochondria
• Each pyruvic acid from glycolysis loses1 CO2
  becomes Acetyl CoA
• Acetyl CoA enters the Krebs cycle, joins a 4
  carbon molecule, releases 1ATP 2 CO2 molecules
• Two electron carriers NADH FADH2 trap the
  energy ,the 4 carbon mol. is regenerated

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Krebs Cycle
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Krebs Cycle? Summary
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Figure 9.6 An overview of cellular respiration
(Layer 2)
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Figure 9.6 An overview of cellular respiration
(Layer 3)
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Electron Transport Chain

• Final stage of CR? inner membrane of the
  mitochondria
• Electron carriers NADH FADH2 transfer the
  electrons carrier molecules in the ETC
• As the electrons move from carrier to carrier,
  energy is released
• Energy released is used to pump H ions across the
  membrane
• When these H ions move back through the ATP
  synthase ADP is converted to ATP

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Figure 9.6 An overview of cellular respiration
(Layer 3)
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Electron Transport Chain

• Not substrate level phosphorylation
• NADH dumps electrons into the cristae walls which
  contains an electron transport system
• Members of the ETC? all but one are proteins w/
  cofactor or conenzyme (prosthetic group)
• Each carrier is more electronegative and lower in
  PE than the previous one

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Transfer of Electrons
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Chemiosmosis

• Takes place in the cristae membrane
• Energy in NADH FAD
• Creates a H gradient that becomes a source of PE
  ? used to do cell work

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Chemiosmosis? Couples ETC to ATP Sythesis
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ATP Synthase

• 3 compartments? hydrogen ion pore
• Rotor
• Rod
• Knob
• Energy of fall causes a change in conformation?
  ADP?ATP
• 1NADH3ATP
• 1FADH22ATP

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Total ATP 38

• Glycolysis
• 4 ATP produced, 2 ATP used
• NET 2ATP
• Krebs
• 2 ATP
• ETC
• 34 ATP

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CO2 O2 Cycle
O2
chloroplast
CO2
mitochondria
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CO2 O2 Cycle
O2
CO2
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Fermentation

• Cells in the absence of oxygen ferment sugars and
  other foods
• The products formed depends on the type of cells
• Process in used in the food industry to produce
  cheese, yogurt, bread, alcoholic beverages, soy
  sauce sauerkraut

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Muscle Cells

• Lactic acid is produced when muscle cells lack
  oxygen
• Glucose? 2 pyruvic acid? 2 lactic acid
• Lactic acid causes muscles to ache? stop take
  deep breaths

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Yeast Cells

• Alcohol is produced, CO2 is also released
• Process is used in the beer wine industry
• Also used in bread making
• Glucose? 2 pyruvic acid? ethyl alcohol
  (evaporates while baking), CO2 released makes
  bread rise