Chapter 8: Photosynthesis

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Chapter 8 Photosynthesis

• 8-1 Energy and Life
• 8-2 Photosynthesis An Overview
• 8-3 The Reactions of Photosynthesis

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Chapter 8 Concept Map p. 200-214
Cell Energy
Life Without Light
ATP
ADP
Chemosynthesis
Joseph Priestleys Experiment
Photosynthesis
Light Independent Reaction
Chloroplast
Equation
Light Dependent Reaction
Thylakoid Membrane
Calvin Cycle
Photolysis
Electron Transport Chain
Chlorophyll
NADP
NADPH
Pigment
Photo System
Grana
Stroma
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ATP as a Molecule

• What processes in a cell need energy?
• Active Transport, Cell Division, Movement of
  Cilia and Flagella, Movement of Muscles.
• ATP Adenosine Triphosphate
• An adenosine molecule with 3 phosphate groups
  attached.
• Bonding phosphates to adenosine takes a lot of
  energy
• Therefore, when ATP is broken down, a lot of
  energy is released.

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Formation of ATP

• Adensosine (the backbone of the ATP molecule) is
  the combination of adenine and ribose.
• Adenine is a nitrogen base molecule also found in
  DNA, and ribose is a sugar also found in DNA.
• The phosphate groups bind to the ribose.

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Formation of ATP

• Phosphate molecules act as magnets with a north
  and south pole.
• As they are arranged on the adenosine molecule,
  they repel each other as would a magnet.
• One phosphate group-AMP
• Two phosphate group-ADP
• Three phosphate group-ATP

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Breaking Down ATP

• A Renewable Cycle!
• A phosphate is released from ATP to form ADP.
• Along with this phosphate group, necessary energy
  is released.
• A free phosphate is then readily reattached to
  the ADP to once again produce ATP.
• Energy is stored in the cell by bonding this
  third phosphate group to an ADP
• As long as the cell has free phosphate groups and
  adenosine, the cell can recycle this energy.

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How a Cell Uses ATP

• ATP is not immediately useful to the cell.
• It must bind with a protein for its phosphate
  group to be released, along with its energy.
• The protein accepts the ATP, helps it release its
  phosphate group, and then releases the leftover
  ADP molecule.
• The protein is now ready to accept a new ATP
  molecule.

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Photosynthesis

• Photosynthesis The process that plants use to
  trap the light energy of the sun and then build
  and store glucose.
• Broken into two different parts
• Light-Dependent Reactions Where light energy is
  converted into chemical energy (ATP).
• Light-Independent Reactions Where chemical
  energy (ATP) is converted into glucose. No light
  required.
• Equation for Photosynthesis
• 6CO2 6H2O ? C6H12O6 6O2

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Photosynthesis Where?

• In the leaves of the plant in the chloroplasts.
  See p.596 Fig. 23.18
• More specifically in the palisade mesophyll of
  the leaf.
• The palisade mesophyll makes up only part of the
  leafs tissue.
• The palisade mesophyll has tons of chloroplasts
  throughout its cells.
• Where-more specifically within the
  chloroplast-does photosynthesis take place?

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Chloroplast Structure
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Photosynthesis - Where?

• Light-dependent rxns. take place in the thylakoid
  membranes.
• The thylakoids use their pigments (chlorophyll)
  to trap the sunlight.
• Review What are the stacks of thylakoids
  called?
• Chlorophyll a and b exist. Between them they
  trap and absorb all wavelengths of visible light
  except green (green is reflected).

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Light-Dependent Reactions

• Sunlight excites electrons in chlorophyll
• Energized electrons are passed through two
  different electron transport chains or strings of
  proteins embedded in the thylakoid membranes that
  are constantly accepting and casting off
  electrons. See p. 211, Fig. 8.10
• An electron transport chain can be located
  anywhere in the cell, usually in the membrane!
• The electron loses energy with each pass.
• Lost energy can be used to make ATP.
• Extra electrons are important later in
  preparation for the light-independent rxns.

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Photolysis add this to notes

• Photolysis The process of water being split by
  the suns energy. See p. 211 Fig. 8.10
• Products of photolysis are
• Oxygen we breathe
• Two electrons
• Two hydrogen ions

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Light Dependent Reactions
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Light-Independent Reactions

• Commonly called The Calvin Cycle- simple sugars
  are produced from CO2 and Hydrogen!!!
• Named after Melvin Calvin
• The main reactant is CO2
• Takes place in the stroma of the chloroplast.
• The stroma is the fluid surrounding the grana in
  a chloroplast.
• See pg. 212

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Where does the glucose go?

• Plants have a vascular system just like we do!
• Instead of blood, their veins carry water and
  food, or in this case glucose.
• Phloem carries glucose from the leaves to the
  rest of the plant
• Xylem cells carry water from the roots in the
  ground to the plants leaves.
• Xylem and phloem cells form tubes through which
  water and sugars can travel.

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Aerobic vs. Anaerobic Double Bubble Map
Electron transport (O2)
Does not require oxygen
Types of respiration
Requires oxygen
Produces 2 ATP
Citric Acid Cycle (CO2)
Anaerobic
Aerobic
Occurs in cytoplasm
Produces 36 ATP
Fermentation LacticAlcohol
Occurs in cell
Glycolysis
Occurs in mitochondria
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Photosynthesis vs. Respiration Double Bubble Map
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Fermentation Tree Map
Fermentation
Alcoholic Ethyl alcoholCarbon dioxideYeastBacte
riaReleases 2 ATP
Lactic Acid Affects musclesReleases 2 ATP
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Photosynthesis Tree Map
Photosynthesis
Dark Reactions Synthesis phaseOccurs in
stromaRequires carbon dioxide and ATPCalvin
CycleProduces glucose (C6H12O6)
Light Reactions Photo phaseOccurs in the
thylakoid membraneRequires sunlight, water, and
chlorophyllPhotolysisProduces oxygen
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Plant Processes Flow Chart