PHOTOSYNTHESIS

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PHOTOSYNTHESIS

• HONORS BIOLOGY

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BIG PICTURE
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PHOTOSYNTHESIS

• Process by which plants use sunlight to produce
  carbohydrates (a way of converting the energy of
  sunlight into chemical energy)
• Plants use PIGMENTS to capture suns energy

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PIGMENT

• A pigment is a colored substance that reflects or
  absorbs light.
• The main pigment in plants is chlorophyll

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ACTUAL PIGMENT MOLECULE
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VISIBLE LIGHT
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PLANT PIGMENTS ABSORB ONLY CERTAIN WAVELENGTHS OF
LIGHT
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CHLOROPHYLL A B
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CHLOROPHYLL A B

• Chlorophyll absorbs blue and red regions of the
  spectrum
• Reflects the green region so we see green

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CAROTENOIDS
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PHOTOSYNTHESIS

• Energy storage process in autotrophic plants
• Within cell organelle called chloroplast
• Necessary pigments concentrated in the inner
  membrane of the chloroplast

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LEAF STRUCTURE
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LEAF STRUCTURE
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LEAF CELL
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CHLOROPLAST
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CHLOROPLAST STRUCTURE
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INNER MEMBRANE
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CHLOROPLAST STRUCTURE
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CHLOROPLAST STRUCTURE
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PHOTOSYNTHESIS REACTIONS

• LIGHT REACTION (Light Dependent)
• Requires light energy
• Produces NADPH (electron carrier), ATP, and
  oxygen
• Happens inside the photosynthetic membranes of
  chloroplast (Thylakoids)
• Chlorophyll molecules are arranged in a specific
  pattern called a photosystem

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PHOTOSYSTEM LOCATION
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What does a photosystem look like?
Surface of Thylakoid
Chlorophyll molecules
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PHOTOSYSTEMS

• PHOTOSYSTEM II
• ATP is produced
• Water is split (source of electrons)
• Oxygen is released (important source of oxygen on
  earth)
• Electrons are then passed on to photosystem I

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PHOTOSYSTEM I

• Accepts electrons from photosystem II
• NADP is coverted to NADPH

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PHOTOSYSTEMS WORK TOGETHER TO MAKE PRODUCTS TO BE
USED IN THE DARK REACTION
NADPH made here
Oxygen released
ATP made here
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LIGHT REACTION

• The ATP NADPH produced in the light reaction
  are used as power in the dark reaction to make
  glucose.

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DARK REACTION

• Dark reaction (light independent)
• Do not require sunlight
• Can occur in day or night
• CO2 enters leaves through pores called stomata
• CO2 is used in the Calvin cycle to produce glucose

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PRODUCTS OF LIGHT REACTION ARE USED IN THE DARK
REACTION
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CALVIN CYCLE

• Also known as carbon fixation
• Cycle because starts and stops with the same
  compound
• Carbon dioxide enters the cycle

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CALVIN CYCLE
It takes 6 CO2 or 6 turns of the Calvin cycle to
produce one molecule of glucose.