Photosynthesis

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Photosynthesis
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The basics

• Photosynthesis is the process by which autotrophs
  convert sunlight to a useable form of energy.
• CO2 H2O light ? C6H12O6 H2O O2

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Why are plants green?

• What makes plants green?
• Pigments Molecules that absorb certain
  wavelengths and reflect others.
• Typically in the visible spectrum of 400-700nm
• 400 nm is purple/blue
• 700 nm is red
• Chlorophyll is the main photosynthetic pigment in
  plants but not the only one.

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Other pigments

• Chlorophyll has 3 forms
• Chlorophyll a is the only type that performs
  photosynthesis
• Chlorophyll b is an accessory pigment that can be
  converted to an a type
• Chlorophyll c can replace chlorophyll b.
• Carotenoids prevent damage to chlorophyll by
  acting as antioxidents
• Beta-Carotene has an orange color and becomes
  Vitamin A.

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Where do you find chlorophyll?

• Chlorophyll is contained in the plant organelle
  the chloroplast.
• A single cell can have as few as one chloroplast
  to thousands of chloroplasts.
• Within a chloroplast are grana, large stacks of
  discs called thylakoids.

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Photosynthesis

• Has 2 main stages
• Light Dependent
• Aka Energy-transduction reaction
• Light converts ADP?ATP
• Light Independent
• Aka Carbon-fixation reaction
• ATP links CO2 into organic molecule chains
• While glucose is considered the main product, it
  is not the major output of plants. Sucrose, a
  disaccharide version is more common.

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Inside the chloroplasts

• Light is absorbed by Photosystem II
• Photosystem II is linked to Photosystem I by an
  electron transport chain.
• Energy leaves Photosystem I to enter the Calvin
  Cycle.
• Calvin Cycle is also known as the C3 pathway.

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C3, C4, CAM

• C3 plants have low energy costs for
  photosynthesis but are limited by oxygen they
  produce.
• C4 plants require more energy but trap CO2 in the
  layers of the plant for continual use
• CAM plants release less water and survive better
  in dry, hot climates

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Examples

• C3 grasses wheat, rye, oats, rice
• C4 grasses maize, sugarcane
• CAM plants cacti, pineapples