Cellular Respiration and Fermentation

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Chapter 9

• Cellular Respiration and Fermentation

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Chemical energy and food

• How much energy is in food?
• When 1 gram of glucose (C6H12O6) is burned in the
  presence of oxygen, 3811 calories are released.
• What is a calorie? A calorie is the amount of
  energy needed to raise the temperature of 1 gram
  of water 1 degree Celsius.

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Chemical energy and food

• On a food label Calories (with a capital C)
  represent kilocalories. 1 kilocalorie 1000
  calories.
• Cells use the energy in glucose by slowly
  releasing it.

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Chemical energy and food

• How many calories are in 2 crackers?
• How many calories are in 6 crackers?

60,000
180,000
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• This SLOW release of energy from glucose is
  called CELLULAR RESPIRATION

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• We think of respiration as breathing
• think of breathing as gas exchange (O2 in and CO2
  out) to help you do cellular respiration
• gas exchange occurs at the cellular level to
  drive cellular respiration
• O2 is a reactant of cellular respiration
• CO2 is a waste product of cellular respiration
• Breathing is just the way you get these gases
  into and out of your body.

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• Cellular Respiration and Fermentation are methods
  by which organisms break down food molecules to
  release energy for life functions.

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• Both processes begin with glycolysis (sugar,
  loosen), breaking down glucose into two molecules
  of pyruvate.
• From here, whether oxygen is present or not
  determines the process that happens next.

Glycoysis
O2
no O2
Fermentation
Krebs Cycle
Electron Transport Chain
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• All organisms must perform some sort of
  respiration or fermentation in order to obtain
  energy from storage molecules (food).

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Overview of Cellular Respiration

• Cellular respiration is the process that releases
  energy by breaking down glucose and other food
  molecules in the presence of oxygen.
• Oxygen glucose ? carbon dioxide water
  energy
• O2 C6H12O6 ? CO2 H2O ATP

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Overview of Cellular Respiration

• What is the balanced chemical equation for
  cellular respiration?
• 6O2 C6H12O6 ? 6CO2 6H2O 36 ATP

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• Mitochondria - Energy
• Inner membrane is highly folded to increase
  surface area

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Glycolysis (part 1)

• Glycolysis is the process by which one molecule
  of glucose is broken in half to produce two
  molecules 3-carbon of pyruvate (sometimes called
  pyruvic acid). It occurs in the cytoplasm.

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Glycolysis

• 10 enzymatic reactions occur during glycolysis.
• The first half of glycolysis requires 2 ATPs and
  the second half forms 4 ATPs and 2 NADHs.
• NET- there are 2 ATPs and 2 NADH formed.

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Fermentation (part 2 option 1)

• Fermentation occurs when no oxygen is present.
• It is termed anaerobic respiration (meaning
  without oxygen).
• It turns NADH back into NAD so that it can be
  recycled and glycolysis can continue.
• There are two types.

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There are two types of fermentation

• a. Alcoholic fermentation- yeast and other
  microorganisms perform this
• pyruvic acid NADH ? alcohol CO2 NAD

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• We can use this to help us make things such as
  bread and wine

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There are two types of fermentation

• b. Lactic Acid fermentation- in a shortage of
  oxygen in your muscle cells, it regenerates NAD
  so glycolysis can continue.
• Lactic acid builds up in your muscles which
  causes pain and soreness.
• pyruvic acid NADH ? lactic acid NAD

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• Lactic acid is also used by bacteria that are
  used to produce yogurt and other foods.
• Also used to make sourdough breads, sauerkraut,
  pickles and olives

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Aerobic Cellular Respiration(part 2 option 2)

• The remaining 90 of the energy from the glucose
  molecule that was not used in glycolysis is used
  in the part of cellular respiration that requires
  oxygen (aerobic).
• Cell Respiration occurs when oxygen IS present-
  termed aerobic respiration. It happens in the
  mitochondria. There are two parts after
  glycolysis the Krebs Cycle and the Electron
  Transport Chain.

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The Krebs Cycle

• Krebs Cycle (Citric Acid Cycle)- Pyruvate is
  broken down into carbon dioxide molecules in a
  series of steps that also form ATP, NADH, and
  FADH2 for use in the Electron Transport Chain.
• Happens in the matrix

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In the Electron Transport Chain,

• Electron Transport Chain- Uses high energy
  electrons from NADH and FADH2 from Krebs cycle to
  build up H ions in the Intermembrane space
  making it positive and the matrix negative.

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In the Electron Transport Chain,

• The H ions will then move through the ATP
  synthase to the negative side causing the ATP
  synthase to turn. Each turn brings ADP and a
  phosphate (Pi) together to form high energy ATP.

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• The Krebs Cycle and Electron Transport Chain
  occur in the mitochondria.

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The Totals

• Cellular respiration produces 36 ATP molecules.
• More ATP is produced with oxygen than without.
  Cellular respiration is more efficient using
  oxygen.

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Energy and Exercise Quick Energy

• Running a short race, you use ATP in your
  muscles, and produce new ATP by lactic acid
  fermentation and cellular respiration.
• When sprinting, you produce most of your ATP
  using lactic acid fermentation because you have
  run out of oxygen for the Krebs cycle.
• You breathe heavily after you finish a race to
  rebuild your ATP supply.

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Energy and Exercise Long-term Energy

• When running a long race, you use carbohydrate
  energy stored as glycogen from your muscles and
  other tissues. This will give you enough energy
  for up to 20 minutes of activity.
• After using up glycogen, your body will use up
  fats for energy.
• Aerobic exercises like running and swimming are
  beneficial for weight control.

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Comparing Photosynthesis and Cellular Respiration

• If storing energy is compared to money in a
  savings account, photosynthesis deposits the
  energy and cellular respiration withdraws the
  money.
• Cellular Respiration is the reverse reaction of
  photosynthesis.

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• What is the formula for photosynthesis?
• 6CO2 6H2O light ? 6O2 C6H12O6
• What is the formula for cellular respiration
  (think about the opposite)?
• 6O2 C6H12O6 ? 6CO2 6H2O ATP

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• Photosynthesis uses CO2 in the atmosphere, but
  cellular respiration puts it back
• Photosynthesis releases O2 into the atmosphere
  but cellular respiration using O2 to release
  energy from the food
• Cellular respiration occurs in all eukaryotes and
  some prokaryotes
• Photosynthesis occurs only in plants, algae, and
  some bacteria. Other organisms (heterotrophs) get
  their food by consuming other organisms.