Photosynthesis

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Photosynthesis

• The Rodney Dangerfield process of Biology

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The Process that Feeds the Biosphere
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Q Where does photosynthesis occur?

• Photosynthetic ORGANISMS include..

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plants, algae, protists, cyanobacteria
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Where does photosynthesis occur?

• (Assume plants)The ORGAN of photosynthesis is.

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Leaf ORGAN of photosynthesis

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Leaf ORGAN of photosynthesis

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Lets take a closer look at a chlorenchyma
(mesophyll) cell

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Introducing the Organelle of Photosynthesis
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The Chloroplast
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Remember this?
Human Organism Redbud
Organ
Tissue
Cell
Organelle
Molecule
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Possible Answers
Human Organism Redbud
Brain Organ
Nervous Tissue
Neuron Cell
Nucleus Organelle
DNA Molecule
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Levels of Organization
Human Organism Redbud
Brain Organ Leaf
Nervous Tissue Chlorenchyma
Neuron Cell Chlorenchyma
Nucleus Organelle Chloroplast
DNA Molecule Chlorophyll
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Equations of Photosynthesis

Complete6 CO2 12 H2O Light energy ? C6H12O6
6 O2 6 H2 O
Net6 CO2 6 H2O Light energy ? C6H12O6 6
O2
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Photosynthesis Cellular Respiration

• Photosynthesis

6 CO2 6 H2O Light energy ? C6H12O6 6 O2
Cellular Respiration C6H12O6 6O2 ? 6CO2
6H2O ATP Energy
RememberFirst Law of ThermodynamicsRedox
Reactions
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Purpose of Photosynthesis?

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Parts of Photosynthesis

• Photosynthesis consists of two processes
• The Light reactions
• The Calvin cycle

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Parts of Photosynthesis

• The Light reactions
• Purpose To trap photons of light energy and
  temporarily store in in molecules of ATP and
  NADPH
• Location surface of the Thylakoid disks

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Note Thyllakoid Disk
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Parts of Photosynthesis

• 2. The Calvin cycle (aka) dark reactions
• Purpose To remove the trapped energy from
  temporary storage, combine with carbon dioxide,
  to make sugar!
• Location Stroma of chloroplast

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Note stroma
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Chlorophyll Key molecule (pigment) of
photosynthesis

The above image is from http//www.nyu.edu80/page
s/mathmol/library/photo.
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Key Vocabulary

• Pigment -
• Photosystem
• photon

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Nature of Light
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(No Transcript)
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Steps of Light Reactions

• See handout ( remember purpose)
• Note reaction center

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What happens when chlorophyll absorbs light?
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Light Reactions!
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Understanding check(Light Reactions)

• Where is energy of photons of light?
• Why do plants need water (during
  photosynthesis)?
• How has oxygen been produced?
• Has carbon dioxide been used?

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Calvin Cycle
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Understanding Check(Calvin Cycle)

• Which products of the light reactions are
  necessary to drive the Calvin cycle?
• What is the most abundant protein on Earth? What
  does it do?(Aside What is the most abundant
  carbohydrate on Earth?)

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Understanding Check(General)

• Do plants use oxygen? Why or why not?
• Do plants produce both oxygen carbon dioxide?

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Big picture 1

• Indicate light or Calvin for each reactant
  and product
• CO2 H2O Light E ? C6H12O6 O2
• (dark) (light) (light) (dark)
  (light)

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Big picture 2

• Indicate how each enters or leaves the plant
• CO2 H2O Light E ? C6H12O6 O2

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Big Picture 3

• Importance of Photosynthesis(3 ways to view
  photosynthesis..)
• 1) Traps energy for plant and for entire
  ecosystem(Remember Plants are
  autotrophs/producers
• 2) C-fixation for plant and for entire
  ecosystem(Remember Plants are
  autotrophs/producers)

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Big Picture 3

• Importance of Photosynthesis
• 3) Produces oxygen for entire planet!
• Note This is an accident!in purple
  bacteriaCO2 H2S Light E ? C6H12O6 S
• Question What organisms USE oxygen?
• For what purpose?

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Evolutionary Perspective

• Earth formed about 4.5 bya
• Original atmosphere was anaerobic (no oxygen)
• Cyanobacteria (first photosynthesizers) released
  oxygen
• Build-up of oxygen allowed eukaryotes and
  multi-cellular organisms to flourish!

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Evolutionary Perspective (cont)

• Oxygen build-up in atmosphere also allowed for
  the formation of OZONE!
• 3 02 ? 2 03
• Why is ozone important?

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Big Picture 4

• Can you list SIX similarities and SIX
  differences/opposites between cellular
  respiration and photosynthesis?

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Big Picture 4 (cont)

• Similarities between mitochondria chloroplast
• Both have internal and external membrane
• Both believed to have originated from once
  free-living bacteria cells(Endosymbiotic Theory)
• Both use chemiosmosis to generate ATP

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Chloroplasts and Mitochondria

• Generate ATP by the same basic mechanism
  Chemiosmosis
• Compare/Contrast
• 2. Movement of H (between what spaces, what
  direction?)

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