Photosynthesis Lecture for Lesson 1
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Transcript of Photosynthesis Lecture for Lesson 1
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Photosynthesis: Converting sunlight into chemical energy
Students who demonstrate understanding can:HS-LS1-5: Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.
+Where does the oxygen (O2) we
breathe come from?
O2 is produced by different kinds of bacteria, algae, and plants (including trees) during photosynthesis.
About 25% of O2 comes
from land plants.
Most of Earth’s O2 comes from the ocean. Released from tiny ocean
plants called, phytoplankton.
+Autotrophs and Photosynthesis
Called “self feeders” or ”producers”.
Organisms that can produce their own food using light, water, carbon dioxide, or other chemicals.
Examples of autotrophs: green plants, some algae, few bacteria.
Most autotrophs use photosynthesis to make their food.
+Overview of Photosynthesis
Light energy gets converted into chemical energy.
Chemical energy is stored in the form of glucose (sugar).
Carbon dioxide, water, and sunlight are used to produce carbohydrates and oxygen.
Occurs in two stages: Light Dependent Reactions Light Independent Reactions
NASA: Seeing Photosynthesis From Space
+Closer Look at Chloroplast
Structures Chlorophyll:
Allows plants to absorb energy from light
Gives leaves their green color
Membrane Envelope: Inner and outer membranes Protects and keep chloroplast
structures enclosed.
Thylakoid membrane: Internal membrane system Flattened sac-like membrane
structures called thylakoids Serve as the sites of
conversion of light energy to chemical energy.
Granum Dense layered stacks of
thylakoid sacs Sites of conversion of light
energy to chemical energy.
Stroma Dense fluid within the
chloroplast Lies inside the envelope but
outside the thylakoid membrane
Site of conversion of carbon dioxide to carbohydrates
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Two Processes of Photosynthesis
Location: Thylakoid Membrane
Reactants: Sunlight and water (H2O)
End Products: ATP, NADPH, and O2
Also called “Calvin Cycle” or Dark Reactions
Location: Stroma
Reactants: ATP, NADPH, and O2
End Products: Glucose
Light Dependent Reactions Light Independent Reactions
Remember: Cells use ATP for energy NADPH is a cofactor in reactions that acts as a reducing agent