Photosynthesis

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Photosynthesis
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Autotrophs

• Auto self
• Troph eating
• Organisms that can produce their own food
  (energy) from inorganic materials (sunlight)

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Heterotroph

• Hetero other
• Troph eating
• Organisms that cannot make its own food. Requires
  organic compounds (other organisms) for its
  principle source of food.

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Chemical Energy and ATP

• All cells use chemical energy carried by
  ATP-Adenosine triphosphate.
• Cells use ATP for functions such as building
  molecules and moving material through active
  transport.

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ATP

• The energy carried by ATP is released when a
  phosphate group is removed from the molecule.
• ATP become ADP (Adenosine diphosphate)
• ADP can become ATP again through a series of
  chemical reactions.

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ATP

• ATP is produced during the breakdown of
  carbon-based molecules.
• Different foods provide different amounts of ATP.
• Carbohydrates (glucose) can make 36 molecules
  of ATP
• Lipids can make 146 molecules

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Special Creatures

• Some organisms do not need sunlight and
  photosynthesis as a source of energy.
• Some organisms live near cracks in the ocean and
  never see sunlight
• Chemosynthesis
• Process by which some organisms use chemical
  energy instead of light energy to make
  energy-storing carbon-based molecules

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Photosynthetic Organisms are Producers.

• Producers
• Produce the chemical energy for themselves and
  for other organisms.
• Photosynthesis
• A process that captures energy from sunlight to
  make sugars that store chemical energy.
• Chlorophyll
• A molecule in chloroplasts that absorb some of
  the energy in visible light

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Photosynthesis in Chloroplasts

• Chloroplasts are in leaf cells
• Grana are stacks of coin-shaped membrane-enclosed
  compartments called thylakoids.
• The membranes of thylakoids contain chlorophyll
  and protein
• Stroma is the fluid that surrounds the grana
  inside the chloroplast.

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Photosynthesis in Chloroplasts

• Light-dependent reactions
• 1. chlorophyll absorbs light.
• 2. energy is transferred to molecules that carry
  energy (ATP).
• Light-independent reactions
• 3. CO2 is added to build larger molecules. Energy
  from the light-dependent reactions is used.
• 4. A molecule of simple sugar is formed. C6H12O6
  (glucose)

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First Stage Light-Dependent Reaction

• Capture and transfer energy.
• There are two photosystems involved photosystem
  II and photosystem I

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Light-Dependent Reaction

• Chlorophyll and other light-absorbing molecules
  capture energy from sunlight.
• Water molecules are broken down into hydrogen
  ions, electrons, and oxygen gas (waste)
• Sugars are NOT MADE during this part of
  photosynthesis

Day 1
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Light Dependent Reaction Photosystem II and
Electron Transport

• Chlorophyll and other light absorbing molecules
  absorb energy from sunlight and that energy is
  transferred into chloropyll.
• The energy is then transferred to electrons.
• 1. Energy is absorbed in sunlight
• High energy electrons leave the chorophyll and
  enter the electron transport chain (a series of
  proteins in the thylakoid)
• 2. Water molecules split
• 3. Hydrogen ions transported

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Light Dependent Reaction Photosystem I and
Energy-Carrying Molecules

• Chlorophyll and other light-absorbing molecules
  absorb sunlight and add it to the electrons from
  photosystem II
• 4. Energy is absorbed from sunlight. Electrons
  are energized.
• 5. NADPH produced.
• In photosynthesis NADPH functions like ATP.
• The molecules of NADPH go to light-independent
  reactions.

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ATP Production

• Final part of the light-reaction.
• 6. Hydrogen ion diffusion
• H ions flow through the thylakoid.
• 7. ATP produced
• ATP synthase take the ions as they flow and makes
  ATP by adding phosphate groups to ADP.

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Light Dependent Reaction Photosystem II and
Photosystem I
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Summary of Light-Dependent Reactions

• PRODUCTS ARE
• NADPH
• Used later to make sugar.
• ATP
• Used later to make sugar.
• Oxygen
• Given off as a waste.

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2nd Stage Light Independent Reaction

• Uses energy from the first stage to make sugar.
• Light-independent reactions take place ANY time
  that energy is available (it doesnt need
  sunlight).
• Light-independent reactions use the NADPH and ATP
  made during the light-dependent reactions to make
  sugar.

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The Calvin Cycle

• Uses the NADPH and ATP from the light-dependent
  reaction, and CO2 from the atmosphere to make
  simple sugars.

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The Calvin Cycle

• 1. Carbon dioxide added.
• CO2 molecules are added to five-carbon molecules
  already in the Calvin Cycle.
• Six-carbon molecules are formed.
• 2. Three-carbon molecules formed.
• ATP and NADPH is used to split the six-carbon
  molecules into two three-carbon molecules.

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The Calvin Cycle

• 3. Three-carbon molecules exit.
• Most of the three-carbon molecules will stay IN
  the Calvin Cycle.
• ONE high energy three-carbon molecule will leave
  the cycle.
• When TWO three-carbon molecules leave the cycle,
  they will bond together to build a six-carbon
  sugar molecule.
• Glucose (C6H12O6)

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The Calvin Cycle

• 4. Three-carbon molecules recycled.
• Energy from ATP is used to change the
  three-carbon molecules that stayed in the cycle
  to five-carbon molecules.
• These five-carbon molecules stay in the Calvin
  Cycle.
• They are added to new CO2 molecules that enter
  the cycle.

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The Calvin Cycle
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Summary of Light-Independent Reactions

• PRODUCTS ARE
• Glucose
• Used to store energy.
• NADP
• Return to the light-dependent reaction.
• Will be changed into NADPH there.
• ADP
• Return to the light-dependent reaction.
• Will be changed into ATP there.

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Functions of Photosynthesis

• Provides material for plant growth and
  development.
• Simple sugars are bonded together to form complex
  sugars like cellulose and starch.
• Starches store energy for the plant.
• Cellulose is a major component of the cell wall.
• Helps regulate the Earths environment.
• Removes CO2 from the atmosphere.

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Photosynthetic Equation

• 6CO2 6H2O C6H12O6 6O2
• Light Dependent Reactions
• Includes Photosystem II
• Electron Transport Chain
• Photosystem I
• Light Independent Reactions
• Includes the Calvin Cycle

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Photosynthetic Equation