Photosynthesis and Cellular Respiration

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Photosynthesis and Cellular Respiration
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How do cells obtain organic compounds for energy?

• Heterotrophs Cannot make their own food
• Autotrophs Can make their own food
• Photoautotrophs Use energy from the sun
  (photosynthesis) to produce organic compounds
  (glucose)
• Plants, algae and some bacteria
• Chemoautotrophs Use energy stored in inorganic
  compounds (chemosynthesis) to produce organic
  compounds
• Some bacteria found at the hydrothermal vents of
  the seafloor

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Photosynthesis

• Method of converting light energy from the sun
  into chemical energy that cells can use
• Divided into the light-dependent and
  light-independent reactions
• Photosynthesis takes place in chloroplasts
• The parts of a chloroplast are as follows
• Thylakoids- disk-shaped structures that contain
  the pigment chlorophyll (absorbs the sunlight)
• Grana- A stack of thylakoids
• Stroma- Liquid between grana

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Draw a Chloroplast
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Overall Photosynthesis Reaction

• 6CO2 6 H2O light energy ? C6H12O6 6O2
• On the left of the arrow are the reactants (the
  components that react together).
• On the right of the arrow are the products.
• Identify how a plant obtains the reactants.

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Light-dependent Reactions

• Chlorophyll (in thylakoids) absorbs the light
  energy
• Plants have 2 types Chlorophyll A and
  Chlorophyll B
• Water molecules are split apart producing H and
  O2
• Electrons flow throughout the thylakoid membrane
  (electron transport chain)
• Energy compounds ATP and NADPH are produced

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Light-independent Reactions (Dark Reactions)

• Occur in the stroma
• ATP and NADPH from the light reactions are used
  to fuel the break down of CO2 and the
  reassembling of the atoms to produce glucose.
• This reassembling is called carbon fixation.
• Carbon fixation occurs in a series of reactions
  called the Calvin Cycle.

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Photosynthesis Practice

• You and a partner need
• 6 orange circles C
• 12 blue triangles H
• 18 pink squares O
• 1 large green oval thylakoid
• 1 small green rectangle ATP
• 1 small green rectangle NADPH
• 1 yellow circle sun ?

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Getting energy out of food

• Plants and animals both use glucose from
  photosynthesis for cell fuel.
• Glucose (or other carbs), proteins, and fats are
  not a form of energy that our cells can use.
• Cellular respiration converts glucose into a
  usable energy form (ATP) for cells.

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Cellular Respiration Overview

• The reactions of cellular respiration occur the
  same way in plants and animals.
• Overall Reaction
• C6H12O6 6O2 ? 6CO2 6H2O
• How is this compared to the photosynthesis
  equation?

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Glycolysis

• Glycolysis is the first process of cellular
  respiration.
• It occurs in the cytosol.
• Glucose (C6H12O6) is partially broken down to
  produce 2 pyruvate (C3H3O3) compounds
• This process yields 2 ATP and 2 NADH for every
  glucose molecule.

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Aerobic Cellular Respiration

• Oxygen requiredaerobic
• Aerobic respiration follows glycolysis.
• It occurs in the mitochondria.
• There are 2 main parts to aerobic respiration
• Krebs Cycle
• Electron Transport Chain

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Krebs Cycle

• Completes the breakdown of glucose
• Takes the 2 pyruvate (C3H3O3) and completely
  breaks them down.
• The carbon and oxygen atoms of pyruvates end up
  in CO2 and H2O
• This is where the CO2 that we exhale is produced!
• 3 NADH and 1 FADH2 and 2 ATP get produced

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Electron Transport Chain

• Here is where most of the energy is produced!
• Electron flow ultimately produces 32 ATP!
• The oxygen that we inhale is the electron
  acceptor at the end of the ETC. This acceptance
  of electrons is what produces the ATP.

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Photosynthesis
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Cellular Respiration
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Cellular Respiration Practice

• You and a partner need
• 5 NADH (green)
• 4 ATP (red)
• 1 FADH2 (green)
• 1 mitochondria (blue)

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Anaerobic Cellular Respiration

• Some organisms (some bacteria) thrive in
  environments with little or no oxygen
• No oxygen used anaerobic
• Anaerobic organisms experience anaerobic cellular
  respiration after glycolysis.
• This produces NO ATP!
• Depending on the type of cell, the end products
  of this are alcohol or lactic acid.

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Energy Tally

• Anaerobic organisms cant be too energetic but
  are important for global recycling of carbon

  Aerobic Anaerobic
Glycolysis    
Krebs Cycle    
Electron Transport Chain    
Total ATP per glucose    
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