1. Cell Energy: Photosynthesis
Academic: Chapter 8
Honors: Chapter 7

2. Energy- Ability to do work No energy = no life Laws of thermodynamics
Energy and life
Energy- Ability to do work
No energy = no life
Laws of thermodynamics
First law- energy can be converted from one form to another, but it cannot be created nor destroyed.
Second law- energy cannot be converted without the loss of useable energy (thermal energy/heat)
Example : Food chains

4. Forms of Energy
Energy comes in many forms:
Light
Heat
Electricity
. . . Energy can also be stored in the bonds of chemical compounds.

5. Autotrophs and heterotrophs
Autotrophs- organisms that make their own food from energy from the sun or other sources
Known as producers
Heterotrophs- organisms that need to ingest or consume food to obtain energy
Known as consumers
ALL organisms have to release the energy in sugars and other compounds to live.

7. Metabolism- all of the chemical reactions in a cell
Photosynthesis- light energy from the sun is converted into chemical energy for use by the cell
Cellular respiration- Organic molecules are broken down to release energy for use by the cell.

8. Chemical Energy and atp
ATP- Adenosine Triphosphate- Energy for the cell
Made of adenosine, ribose and three phosphates
ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate
ADP + P

9. CHEMICAL ENERGY AND ATP (Not in notes)
Storing energy- when bonds are formed, energy is stored
ADP- Adenosine diphosphate is similar to ATP, but with two phosphates instead of three
Energy is stored when another phosphate is added to ADP

11. Energy is released when bonds are broken
Releasing energy
Energy is released when bonds are broken
When a phosphate is removed from ATP, energy is released
As many as two phosphates can be removed from ATP
Remove one phosphate = ADP
Remove two phosphates = AMP (Adenosine Monophosphate)

12. Using biochemical energy
1. Cells use ATP for active transport, to move organelles in the cell, and to synthesize proteins and nucleic acids
2. Cells do not keep large amounts of ATP in the cell. The cell can regenerate ATP from glucose as needed
Cellular Respiration
3. ATP is great for transferring energy, but not for storing it.

13. Where do trees get their mass from? Veritasium Video
Video from:

14. Photosynthesis overview
Photosynthesis- The process by which plants use sunlight to convert water and carbon dioxide into sugar
The photosynthesis equation:
6 CO2 + 6 H20  C6H12O6 + 6 O2
Carbon dioxide and water  sugar and oxygen
What are the products and the reactants?

15. photosynthesis requires light
Light is a mixture of wavelengths – ROY G BIV
Pigments- light absorbing molecules- there are different types of pigments
Chlorophyll- principal pigment that absorbs light in the blue-violet and red regions, but not the green
There are accessory pigments: like carotenoids (think carrot)
Chlorophyll is found in the chloroplasts of leaves
This is why chloroplasts look green

16. Chlorophyll a & b Blue and red
Chlorophyll is best at absorbing ____________
Does not absorb ______________________
Green and yellow

17. Blackest Substance

18. Photosynthesis Reactions
Photosynthesis occurs within the chloroplasts of specialized cells within the leaves of plants.

19. Parts of the Chloroplast
Stroma –
Liquid inside the chloroplast. Surrounds the thylakoid membranes.
Grana – (granum plural)
Stacks of thylakoid membranes
Thylakoid –
Membranes containing photosystems
Photosystems –
Light capturing systems
Parts of the Chloroplast

20. Draw this in your notes

21. Two Processes of Photosynthesis
1. Light Dependent Reaction 2. Calvin Cycle (Light Independent Reaction)

22. The light reaction
Takes place in the membrane of the thylakoids

24. Steps to the light reaction: Thylakoid membrane
1. Photons of light strike photosystem II in the thylakoid membrane
Light dependent
2. This causes water to split H2O  H+ AND O
The hydrogen's are now positive (protons) because the e- (electron) that they had are now “excited” and move to the Electron Transport Chain- ETC
ETC- think of a frying pan to move hot coal……
As the e- travels through the ETC, the energy is used to pump more H+ into the thylakoid space

26. The oxygen leaves out the stomata (pores in the leaf)
The H+ remain in the inside of the thylakoid
3. The e- travels through the ETC until it reaches photosystem I where it is re-excited with another photon of light
4. The re-excited electron is used to convert NADP+ into NADPH
NADP+ is an electron carrier that will take the electrons into the second phase of photosynthesis

28. 5. The H+ (protons) that are now in a HIGH concentration in the thylakoid space are now used to create ATP from ADP.
As they flow through to the stroma they pass through a protein that adds a phosphate to ADP (ADP + P = ATP)
6. The ATP and the NADPH now head to the Calvin Cycle to act as the energy to drive the reaction
Summary: Reactants- H20 and Light
Products – O2 ( as waste), ATP and NADPH

31. The Calvin Cycle
Takes place in the stroma (empty space)

32. Steps to the Calvin cycle: stroma
The ATP and NADPH from the light reaction are used to “fuel “ the Calvin Cycle
1. (6) CO2 enter through the stomata (pores in the leaf)
2. CO2 combines with a (6) 5-carbon sugar Ribulose (1+5=6)
(6) 6-carbon sugars!
3.The 6 carbon sugars are then broken down into 12 3-carbon sugars
Because they were unstable
4. The 2 3-carbon sugars leave to make Glucose
5. The remaining 3-carbon sugars continue in the cycle for the next round

34. What it really looks like

35. Summary of the Calvin cycle
Reactants- ATP, NADPH , and CO2 Products: Glucose

37. Summary of photosynthesis
Two step process
1. Light Dependent Reaction in the Thylakoid membrane
2. Light Independent Reaction (Calvin Cycle) in the Stroma
The reactants : CO2 and H2O
The products: C6H12O6 AND O2

38. What effects the rate of photosynthesis?
Temperature
CO2
Light
Water