1. How plants (and some algae and bacteria) make their own food video
Photosynthesis
How plants (and some algae and bacteria) make their own food
video

2. Recall:
Plants use the energy of sunlight and the green pigment chlorophyll to convert carbon dioxide and water into the sugar glucose.

3. The Equation
What are the reactants or ingredients necessary to carry out photosynthesis?
Carbon Dioxide (CO2)
Water (H2O)
Solar energy (sun)
What are the products?
Glucose (C6H12O6)
Oxygen (O6)
So the formula is:
CO H2O + sun → C6H12O O2 6 6 6
How can we balance this equation?

4. Heterotrophs vs. Autotrophs
Create their own food from sun or inorganic chemicals
Photoautotrophs
obtain energy from sunlight
Chemoautotrophs
obtains its nourishment through the oxidation of inorganic chemical compounds as opposed to photosynthesis
Heterotrophs
They need to consume plants– or other animals that have consumed plants– in order to obtain products such as glucose

5. Photosynthesis is vital to life on Earth
Animals are not able to create their own food from inorganic compounds.
Animals EAT food, which is then broken down through cellular respiration (the breakdown of glucose to provide energy), which all living cells need to perform.
Cellular respiration produces carbon dioxide and water, which can be used for photosynthesis.

6. Anatomy of a Leaf

7. LIGHT DEPENDENT REACTION
The goal:
Pass the electrons of water to chlorophyll, and down the photosystems I and II to make Energy (ATP and NADPH)
Scene:
These reactions occur in the thylakoid membrane stacks (The Grana)
Animation

8. The Players:
Photosystems (PS) II (most reactive at a wavelength of 680nm) & Photosystem I (most reactive at a wavelength of 700nm) –
located in the thylakoid membranes (grana) inside the chloroplast;
each photosystem contains a few hundred chlorophyll molecules.
Chlorophyll-
a green pigment, absorbs the red and blue wavelengths of sunlight and becomes photoexcited to start photosynthesis.

9. Electrons-
When photoexcited by sunlight, they leave a chlorophyll molecule in PS II and travel through a series of proteins (called an electron transport chain) to PS I and its electron transport chain.
Water-
is split into oxygen, hydrogen, and electrons in a process called photolysis to replace the electrons lost from PS II.
This is where the oxygen we breathe comes from (a by-product of photosynthesis!)
water is the ultimate source of electrons for photosynthesis!
animation

10. Electron Transport Chain (ETC)
A group of compounds that pass electrons from one to another via redox reactions coupled with the transfer of protons across a membrane to create a proton gradient that drives ATP synthesis
Sort of like a bucket brigade
ATP–
Finally, the hydrogen ions (H+) inside the thylakoid form a proton gradient.
When there are more protons in the inner thylakoid space, they pass back to the stroma through ATP Synthase (an enzyme) which supplies the energy to produce ATP from ADP (this is called chemiosmosis).

11. Animation- another overview of the process
ATP Synthase-
an enzyme that can synthesize ATP from ADP and inorganic phosphate by using a concentration gradient
NADPH—
Ferredoxin, the last electron acceptor in the second ETS, "hands" the electrons from PS I to NADP which then adds a H+ from the stroma to form NADPH.
Animation- another overview of the process

12. Light Dependent Reaction Summed Up
Another animation