Chapter 8 Cellular Energy

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Chapter 8 Cellular Energy

• 8.3 Cellular Respiration

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Cellular Respiration

• Process of breaking down food to produce ATP
• ALL living things do cellular respiration, even
• Plants
• Bacteria
• Eukaryotes in the mitochondria
• Prokaryotes in the cytoplasm

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Cellular Respiration

• Overall reaction
• C6H12O6 O2 CO2 H2O energy

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Cellular Respiration

• Three Stage Process
• Glycolysis anaerobic
• Citric Acid Cycle aerobic
• Electron Transport Chain aerobic

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Cellular Respiration Overview
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Glycolysis

• Happens in the cytoplasm
• Need to use two ATP before can get ATP out of the
  process
• One glucose is split and converted into two
  pyruvate yields four ATP (two net ATP)

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Citric Acid Cycle or Krebs Cycle

• Happens in the mitochondrial matrix
• CO2 produced
• Per turn of the cycle yields
• 1 ATP
• 3 NAPH
• 1FADH2

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Electron Transport Chain
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Electron Transport Chain

• Located within the inner mitochondrial membrane
• Converts NADH and FADH2 into ATP
• Energized electrons are passed along a series of
  proteins
• Some energy is converted directly into ATP
• Other energy causes H ions to be forced out of
  the inner mitochondrial matrix

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Electron Transport Chain cont.

• The force of H ions back into the mitochondrial
  matrix through the enzyme ATP synthase provides
  the energy for ATP synthesis
• Oxygen is the final electron acceptor
• Without oxygen the transport chain would shut
  down like a traffic jam
• Traffic (electrons) would back up and shut down
  the Krebs Cycle as well

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Electron Transport Chain cont.

• For every NADH get 3 ATP
• For every FADH2 get 2 ATP
• Overall get a net of 32 ATP from one molecule of
  glucose
• Balanced equation
• C6H12O6 6O2 6CO2 6H2O 32 ATP

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Fermentation

• Occurs when O2 is not present, no aerobic
  respiration, no Krebs Cycle, no Electron
  Transport Chain
• Allows the continuation of glycolysis by the
  removal of pyruvate
• Some organisms in anaerobic environments produce
  energy by fermentation all the time

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Fermentation Two Types

• Alcoholic
• Yeast
• Produce CO2, ethyl alcohol and 2 ATP from
  pyruvate
• Important in bread and alcoholic beverage
  industries

• Lactic Acid
• Animal muscle cells, some bacteria and some
  plants
• Produce lactic acid and 2 ATP from pyruvate
• Get sore, burning muscles
• Liver converts lactic acid back to pyruvate when
  O2 is present

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Comparing Photosynthesis and Cellular Respiration

• Both use electron transport chains
• Both use cycles of chemical reactions
• Both use electron carrier proteins
• Both use concentration gradient of H ions

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Comparing Photosynthesis and Cellular Respiration

• Photosynthesis
• Food accumulated
• Solar energy stored in glucose
• CO2 taken in, O2 given off
• Occurs only in presence of chlorophyll with
  sunlight

• Cellular Respiration
• Food broken down
• Glucose energy released
• O2 taken in, CO2 given off
• Occurs in all living things all the time