1. Part 1: Photosynthesis Section 4.2 & 4.3
Cell Energy
Part 1: Photosynthesis
Section 4.2 & 4.3

2. Important molecules in cellular energy:
CO2 = carbon dioxide gas
H2O = water
C6H12O6 = glucose (sugar)
O2 = oxygen gas

3. Important molecules in cellular energy:
ATP = chemical energy
NADPH = energy molecule that receives and gives away e- (electrons) to drive chemical reactions

4. ATP gets recycled AdenosineTriphosphate
Loses a P to use energy
Gains a P to make energy
ADP
ADP = AdenosineDIphosphate – It’s ATP that is missing 1 P!

5. NADPH gets recycled, too Nicotinamide Adenine Dinucleotide Phosphate(+ Hydrogen)
It cycles from NADPH to NADP+ back to NADPH, etc.
It carries electrons (held by H) and gives them away during the second stage of photosynthesis – the Calvin Cycle.
NADPH
NADP+

6. Photosynthesis
Photosynthesis: the process for the conversion of light energy into chemical energy (ATP) stored in organic compounds (glucose)

7. Photosynthesis Equation
Carbon dioxide
Water
Glucose
Oxygen gas
PHOTOSYNTHESIS

8. Photosynthesis happens in 2 parts:
Step 1: Light Dependent- light is absorbed to make energy for light independent.
Happens in the thylakoid membrane of a chloroplast
Step 2: Light Independent (Calvin Cycle)– uses energy from the light reactions to make sugar.
Happens in the stroma of a chloroplast

9. Sketch this chloroplast!

10. Chloroplasts

11. Overview of Photosynthesis
CO2
Chloroplast
Light
NADP+
ADP + P
LIGHT REACTIONS (in grana)
CALVIN CYCLE (in stroma)
ATP
Electrons
NADPH O2
Sugar

12. Light Reactions – Detailed steps:
Light is absorbed by chlorophyll
H2O molecules are split to provide e- and H+ that will enter an electron transport chain to produce:
ATP
NADPH
Oxygen from the splitting of H2O is released as waste
Will be used in the Calvin Cycle
2 H2O  e- + 4 H+ + O2

13. http://youtu.be/sQK3Yr4Sc_k (2:42)
Time for video clips!
(2:42)

14. Check for Understanding
1. What happens to the oxygen created during the light reactions of photosynthesis?
a. It is used in the next step of photosynthesis
b. It is discarded as a waste product
c. It is used to make water
d. It becomes a part of glucose

15. Check for Understanding
2. What is the general purpose of the light reactions of photosynthesis?
a. To make oxygen
b. To convert chemical energy into light energy
c. To convert light energy into chemical energy
d. To make glucose.

16. The Calvin Cycle

17. The Calvin Cycle (sometimes called “the Dark Reactions”)
Calvin Cycle: Creates glucose using ATP and NADPH from the light reactions as well as CO2 from the air
Happens in the liquid stroma of a chloroplast
Carbon Fixation: the incorporation (adding) of CO2 into organic compounds
Happens in Calvin Cycle

18. Plant Food
The plant stores the excess sugar as starch in the roots, seeds, and fruit of the plant.

19. Check for Understanding
2. What is the general purpose of the light independent reactions (Calvin cycle) of photosynthesis?
a. To make oxygen
b. To convert chemical energy into light energy
c. To convert light energy into chemical energy
d. To make glucose.

20. Energy overview ATP Photosynthesis Cellular Respiration sun CO2 O2 H2O
plants
H2O
CO2
glucose O2
animals, plants
Cellular Respiration
The Great Circle of Life,Mufasa!
ATP