1. Introduction to
PHOTOSYNTHESIS

2. Cell Energy & Photosynthesis (Chapter 8)
All living things require energy to function.
Heterotrophs (animals/consumers) get their energy by consuming other living things.
Autotrophs (plants) are capable of producing their own food, with the help of chloroplasts and chlorophyll.
In all cells, energy from food is stored in the chemical bonds of a molecule called ATP (adenosine triphosphate)
Energy is stored in phosphate bonds.
Adenosine P

3. Cell Energy & Photosynthesis
When ATP releases a phosphate group, energy is released and ATP becomes ADP (adenosine diphosphate)
ADP can reform ATP by bonding with another phosphate group.
Adenosine P + P P

4. Photosynthesis
Photosynthesis: the process plants use to trap the sun’s energy and make glucose to store energy.
Photosynthesis occurs in 2 phases:
1) Light Dependent Reactions
2) Light Independent Reactions (Calvin Cycle)

5. PHOTOSYNTHESIS 6CO2 + 6H2O ----Sun Light---> C6H12O6 + 6O2
Occurs in the chloroplast
Chlorophyll is the main pigment absorbing the light energy
Thylakoid– disklike structure in the chloroplast (think frisbee)
Grana- stack of thylakoids (think stack of frisbees)
Stroma- open area inside the chloroplast

7. LIGHT-Dependent REACTIONS
6CO2 + 6H2O ----Sun Light---> C6H12O6 + 6O2
Occurs in the THYLAKOID MEMBRANE of the chloroplast (in the “frisbee”)
Water is turned into Oxygen:
Photo System II splits water molecules which releases OXYGEN (O2)
Light energy is STORED in ATP and NADPH molecules
ATP and NADPH go to the stroma (open space of chloroplast) to finish the photosynthesis reaction

8. CALVIN CYCLE (Light-Independent Reactions)
6CO2 + 6H2O ----Sun Light---> C6H12O6 + 6O2
Occurs in the STROMA (chloroplast’s open space)
Carbon Dioxide (CO2) is turned into Glucose (C6H12O6)
CO2 combines with other carbon molecules and Rubisco to eventually form GLUCOSE
The energy needed to transform the CO2 is released from ATP and NADPH, changing them into ADP+ and NADP+
NO SUNLIGHT IS NEEDED FOR THIS PART!

11. STROMA
GRANUM
THYLAKOID
C6H12O6 (sugar)

12. CELLULAR RESPIRATION: the process that releases energy from food using oxygen

13. CELLULAR RESPIRATION C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY
EXACT OPPOSITE of photosynthesis!
3 stages:
GLYCOLYSIS (Stage 1)
KREB’S CYCLE (Stage 2)
ELECTRON TRANSPORT CHAIN (Stage 3)
Occurs in MITOCHONDRIA

14. Mitochondria Structure

15. Step 1: Glycolysis GLYCOLYSIS: “Glucose Splitting”
Occurs without oxygen (anaerobic)
In the CYTOPLASM of the cell
Glucose is broken down into PYRUVATE molecules
2 ATP are produced

16. Step 2: Kreb’s (Citric Acid) Cycle
KREB’S CYCLE (Citric Acid Cycle)
Requires oxygen to function (aerobic)
Occurs in the MITOCHONDRIAL MATRIX
Pyruvate is broken down into CO2 molecules
2 more ATP are produced

17. Step 3: Electron Transport Chain
Requires oxygen to function
Occurs on the inner MITOCHONDRIAL MEMBRANE
Electron transport chain pumps H+ ions across membrane to make ATP
6 H2O and 32 ATP produced

18. _____________
Most Organisms
______________
Yeast

19. 32 ATP H2O O2 CO2 Glycolysis Glucose 2 ATP Electron Transport Chain
_____________
Most Organisms
Glucose O2
2 ATP
Glycolysis
Electron
Transport Chain
Pyruvate
Krebs Cycle
32 ATP
______________
Yeast
2 ATP
H2O
CO2

20. So… what happens when Oxygen is not available?
Start with Glycolysis, and then…
Fermentation

21. Fermentation
Anaerobic process used after glycolysis to make more ATP when oxygen is not available
Lactic Acid Fermentation (Most organisms)
Enzymes convert pyruvate into LACTIC ACID
Sore muscles = lactic acid build up
Used to produce dairy products
Alcohol Fermentation (Microorganisms & Yeast)
Enzymes convert pyruvate into ETHYL ALCOHOL and CO2
Occurs in yeast and some bacteria

22. 32 ATP H2O O2 CO2 Glycolysis Glucose 2 ATP Electron Transport Chain
_____________
Most Organisms
Glucose O2
2 ATP
Glycolysis
Electron
Transport Chain
Pyruvate
Krebs Cycle
32 ATP
______________
Yeast
2 ATP
H2O
CO2

23. 32 ATP H2O O2 CO2 Glycolysis Fermentation Glucose 2 ATP Electron
_____________
Most Organisms
Glucose O2
2 ATP
Glycolysis
Electron
Transport Chain
Pyruvate
Krebs Cycle
Fermentation
32 ATP
2 ATP
Lactic Acid
______________
Yeast
Alcoholic
H2O
CO2

24. Big Picture
Photosynthesis removes carbon dioxide from the atmosphere, and respiration puts it back.
Photosynthesis puts oxygen into the atmosphere, and respiration uses oxygen to release energy from food.