Photosynthesis

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Photosynthesis
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Photosynthesis

• Sun--source of all energy on earth.
• Autotrophs
• Examples
• Photosynthesis
• Chemosynthesis
• Heterotrophs
• Herbivores
• Carnivores
• Omnivores

• 600 billion tons of carbon dioxide taken in
• 400 billion tons of oxygen released
• Van Helmont

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Photosynthesis

• Eukaryotes
• Chloroplasts
• stroma
• grana
• thylakoids
• thylakoid membranes
• chlorophyll
• antennae pigments
• xanothophyll

• Carotene
• phycobilin
• photosystems
• reaction centers
• Prokaryotes
• cell membrane

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Chlorplasts
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Photosynthesis

• Light dependent or light reactions
• Products
• ATP
• NADPH
• Oxygen gas
• Light Independent Reactions
• Calvin Cycle
• Reduction of Carbon Dioxide

• Light Dependent Reactions
• Electromagnetic Spectrum
• Photons
• wavelength
• frequency
• Chlorophyll
• Magnesium
• Similarity to Hemoglobin

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Photosynthesis

• Why are plants green?
• Absorbance of red and blue light
• Carotenoids
• Absorption spectrum
• Why do leaves change colors in the fall?

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Light Dependent Reactions

• Quantum Theory
• Caused by absorbance of light energy.
• Similarity to a solar panel.
• Electron acceptors.
• Electron carriers
• Electron Transport
• oxidation/reduction
• photolysis
• products

• Must occur first.
• Thylakoids
• photosystems
• reaction center
• Photosystem I
• P700
• Photosystem II
• P680
• Excitement and Displacement of electrons

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Light Dependent Reactions

• Electron Transport System
• water to Photosystem II to Photosystem I to NADP
• NADP--electron acceptor
• NADPH formation
• noncyclic photophosphorylation
• pumping in of hydrogen ions

• Creation of hydrogen ion gradient
• Impermeability of the thylakoid membrane.
• ATP Synthase
• Chemiosmosis
• ATP Synthesis
• Phosphorylation
• Cyclic Photophosphorylation

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Light Dependent Reactions

• Noncyclic Photophosphorylation vs. Cyclic
  photophosphorylation
• Noncyclic found in most plants and
  photosynthesizers.
• Cyclic found in some bacteria
• Products of noncyclic include NADPH, ATP, and
  oxygen gas.
• Products of cyclic include ATP and oxygen gas.

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Light Independent Reactions or the Calvin Cycle

• Solar energy is already converted to chemical
  energy in the form of ATP and NADPH, why is there
  a need for the Calvin Cycle?
• Role of glucose and sucrose
• Reduction of CO2
• 1st step is carbon dioxide fixation

• 3 pathways for doing this
• C3 Plants
• C4 Plants
• CAM plants

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Plant Leaf Anatomy

• Occurs in mesophyll
• CO2 fixed to a five carbon molecule and then
  splits into 2 three carbon PGA molecules.
• These are reduced and energy is added (from ATP
  and NADPH) to form PGAL
• 2 of these combine to form glucose

• Stomates
• Guard Cells
• Mesophyll
• Palisades parenchyma
• Spongy Parenchyma
• Bundle Sheath
• C3 Plants
• RUBP Carboxylase
• Fixation of carbon dioxide.

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C3, C4, and CAM Plants

• Bundle sheath
• RUBP carboxylase
• C4 Examples
• sugar cane, corn, bermuda grass, sorghum
• CAM plants
• advantages
• Examples pineapple, cactus, lillies, orchids
• Why dont C4 CAM push out C3?

• C3 examples
• legumes, wheat, oats, barley, rice
• disadvantages
• dehydration
• photorespiration
• C4
• PEP carboxylase
• advantages

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C4 Plants
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CAM Plants