Chapter 9 Cell Respiration

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Chapter 9Cell Respiration
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Cell Respiration

• Food provides living things with the energy
  needed to live and reproduce
• Energy in food is measured in calories
• Energy to raise 1 g water 1C
• Calorie 1000 calories
• The process of releasing energy from glucose
  starts with a pathway called glycolysis.

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Energy Options
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Overview of Cell Respiration

• Cellular respiration is the process that releases
  energy by breaking down glucose and other food
  molecules in the presence of oxygen.
• Chemical equation C6H12O6 6O2 ? 6CO2 6H2O
  energy exact opposite of photosynthesis this
  makes a cycle

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Cell Respiration glycolysis, Krebs cycle,
electron transport chain
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Glycolysis

• Glycolysis is process in which one molecule of
  glucose is broken in half, producing two
  molecules of pyruvic acid, a 3-carbon compound
• - Occurs in cytoplasm of cell
• The energy from glycolysis is stored in 2 ATP
  molecules
• 4 high-energy electrons are accepted by NAD to
  make NADH, which goes to the electron transport
  chain

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Glycolysis
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Energy in Absence of Oxygen

• Fermentation releases energy from food without
  using oxygen known as anaerobic respiration not
  in air
• Fermentation starts with glycolysis and then
  converts NADH to NAD to allow glycolysis to
  continue producing ATP

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• There are 2 main types
• Alcoholic fermentation
• produces ethyl alcohol, carbon dioxide NAD
• Carried out by yeast and other microscopic
  organisms
• Used in bread making

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• Lactic acid fermentation
• Produces lactic acid, NAD
• Occurs in your muscles when there is not enough
  oxygen and unicellular organisms
• Results in cramps because lactic acid builds up
• Used in production of cheese, yogurt, buttermilk,
  sour cream

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The Krebs cycle

• During the Krebs cycle, pyruvic acid from
  glycolysis is used to make carbon dioxide, NADH,
  ATP, and FADH2.

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Electron Transport

• The electron transport chain used high-energy
  electrons from the Krebs cycle to convert ADP to
  ATP.

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Net ATP Production
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Glucose
2 Pyruvic acid
Krebs Cycle
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Energy and Exercise

• A runner has enough stored ATP for about 50
  meters, then the muscles need to use lactic acid
  fermentation to produce ATP in addition to
  cellular respiration last about 90 seconds

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• Your body stores long-term energy in the form of
  the carbohydrate glycogen (15-20 minute store),
  then as fats these are broken down for exercise
  longer than 90 seconds

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Comparing Photosynthesis and Cellular Respiration
Photosynthesis Cellular Respiration
Function Energy capture Energy release
Location Chloroplasts Mitochondria
Reactants CO2 and H2O C6H12O6 and O2
Products C6H12O6 and O2 CO2 and H2O
Equation 6CO2 6H2O energy ? C6H12O6 6O2 6CO2 6H2O energy ? C6H12O6 6O2