1. Photosynthesis and Cellular Respiration

2. Trapping the Sun’s Energy
The process by which plants capture energy from the sun to build carbohydrates through chemical pathways is called photosynthesis
Solar energy converts water and carbon dioxide into chemical energy stored in simple sugars
The simple sugar that photosynthesis produces is glucose which the plant uses to store energy.
The equation that represents photosynthesis is:
6CO2 + 6H2O  C6H12O6 + 6O2
Solar energy

3. Phases of Photosynthesis
Photosynthesis requires energy from the sun, but the sun is not available 24 hours a day.
Photosynthesis must occur in two phases
Light-dependent Reactions (light reactions)
Convert light energy into chemical energy (ATP and NADPH)
Light-independent Reactions (dark reactions)
Uses the ATP and NADPH from the light-dependent reactions to build glucose
6CO2 + 6H2O  C6H12O6 + 6O2
Solar energy

4. The Role of Chloroplasts and Pigments
Photosynthesis takes place in the chloroplasts
Light-dependent reactions take place in the membranes of the thylakoid disks (contain chlorophyll)
Light-independent reactions take place in the stroma (thick fluid that forms the framework of a chloroplast)

5. The Role of Chloroplasts and Pigments
The thylakoid membranes contain the pigments that can absorb certain wavelengths of sunlight.
The most common pigment in the chloroplasts is chlorophyll.
Chlorophyll a and b absorb most wavelengths of light except for green. Green is reflected making the plants appear green.
In the fall, plants reabsorb chlorophyll leaving other pigments that reflect other wavelengths of light – making the leaves appear red, yellow, or orange.
2nd Hour left off here 9/5/2012

6. Light-dependent Reactions
Sunlight strikes the chlorophyll molecules in the thylakoid membrane.
Light energy is transferred to electrons
The electrons become highly energized and are passed down an Electron Transport Chain

7. Light-dependent Reactions
The Electron Transport Chain is a series of proteins in the thylakoid membrane
As the electrons are transferred from one protein to another, some energy is released which
helps join ADP and Phosphate to form ATP
Pump hydrogen ions into the center of the thylakoid disk to join H+ and NADP+ forming NADPH (electron carrier)
ATP and NADPH will be used during the light-independent reactions

8. Light-dependent Reactions
The electrons excited by the light energy that passed down the electron transport chain and left with NADPH need to be replaced so the reaction can happen again.
To replace those electrons, a water molecule is split (photolysis), sending electrons back to the chlorophyll and releasing Oxygen and Hydrogen ions into the atmosphere – this supplies the oxygen that we breathe
Photolysis 

9. Light-dependent Reactions
Solar Energy absorbed by chloroplasts
Oxygen released
ATP Released
Products of Light Reactions (ATP and NADPH) fuel the dark reactions
NADPH released

10. Light-independent Reactions
The second phase of photosynthesis does not require light and is called the Calvin Cycle.
The Calvin Cycle occurs in the stroma of the chloroplast.
The Calvin Cycle uses the ATP and NADPH that was built during the light-dependent reactions

11. The Calvin Cycle Uses Carbon Dioxide from the air
Uses ATP and NADPH from light reactions
Uses another ATP to replenish RuBP
Builds a glucose molecule

12. Photosynthesis Equation
Light Energy
6CO2 + 6H2O C6H12O6 + 6O2
chlorophyll
Carbon Dioxide from the air – Used in the Calvin Cycle during the Dark Reactions
Glucose Made in the Calvin Cycle during the Dark Reactions
1st Hour Left off Here – 9/7/11
Oxygen Released during Photolysis in the Light Reactions
Water Split during Photolysis in the Light Reactions
Plants can use this glucose molecule for energy during Cellular Respiration. Plants can also convert this glucose molecule into other organic compounds such as proteins and fats/lipids or other carbohydrates like starch and cellulose

13. 3 Factors that Affect Photosynthesis
Carbon Dioxide (CO2)
Without CO2, the plant would not have one of the raw materials needed in the photosynthesis equation
CO2 is used in the first step of the Calvin Cycle
Temperature
The temperature must be in the appropriate range for the plant in order for photosynthesis to properly occur

14. 3 Factors that Affect Photosynthesis
Intensity of Light
If the intensity of light is lower, the available energy for photosynthesis is lower.
In a greenhouse, if the light source is further away, intensity is lower and less photosynthesis can occur
If light is not available at all, the light-dependent reactions cannot occur (nor can they provide the materials used in the light-independent reactions)

15. IMPORTANT!!!!
Why are photosynthesis and cellular respiration often described as being complementary reactions?
Photosynthesis
Carbon Dioxide + Water are taken into the plant
Glucose + Oxygen are produced
Cellular Respiration
Glucose + Oxygen are used for cellular respiration
Cellular respiration releases Carbon Dioxide + Water
Therefore, products of photosynthesis are the reactants for cellular respiration AND the products of cellular respiration are the reactants for photosynthesis

16. Nutrients + oxygen  water + ATP + CO2
Cellular Respiration
Cellular Respiration: Process by which mitochondria break down food molecules to produce ATP in plants and animals
Nutrients + oxygen  water + ATP + CO2
Changes organic chemical energy (glucose) into inorganic chemical energy (ATP)
There are three stages of Cellular Respiration
Glycolysis
Anaerobic – does not require oxygen
Citric Acid (Krebs) Cycle
Aerobic – does require oxygen
Electron Transport Chain
2nd Hour Left off here 9/7

17. Glycolysis
Glycolysis: Breaks down glucose into two molecules of pyruvic acid (a colorless acid formed as an important intermediate in metabolism or fermentation)
This reaction uses enzymes and takes place in the cytoplasm of the cell (anaerobic reaction)
Produces
2 pyruvic acid molecules (used in the next step of Cellular Respiration)
2 ATP molecules (energy the cell can use)
2 NADH (electron carrier)

18. Into the Mitochondria…
Before the next step of Cellular Respiration can occur, the pyruvic acid molecules must go into the mitochondria
The two oxygen-dependent (aerobic) reactions are the Citric Acid Cycle (or Krebs Cycle) and the electron transport chain
Pyruvic acid  CO2 + water + ATP

19. Citric Acid/Krebs Cycle (see page 138 in your book)
CO2 is released
Pyruvate from Glycolysis fuels the cycle
CO2 is released
NADH and FADH2 is released
ATP is released

20. Electron Transport Chain
Electron Transport Chain uses the electron carriers (NADH and FADH2) to pass electrons down the protein chain and slowly release energy that is used to form ATP and water molecules
Electron Transport Chain transfers the most energy

21. Electron Transport Chain
Cellular Respiration
ATP
Glycolysis
Glucose
Pyruvic Acid
CO2
Citric Acid Cycle
Pyruvic Acid
ATP
NADH and FADH
Water
NADH and FADH
Electron Transport Chain
Oxygen
ATP

22. Cellular Respiration Equation
C6H12O6 + 6O CO2 + 6H2O + energy
Carbon Dioxide – waste product of the Citric Acid Cycle
Water – released from Electron Transport Chain
Glucose made in photosynthesis by plants or consumed by animals
Used in Glycolysis
ATP released from Glycolysis, Citric Acid Cycle, and Electron Transport Chain
Oxygen from the atmosphere Used in Electron Transport Chain
Between ATP can be made with this process. This ATP can be used by the cells for cellular metabolism.

23. Fermentation
When oxygen is not available anaerobic respiration, fermentation, can follow glycolysis in order to continue to produce energy.
This is not as efficient as aerobic respiration and produces far fewer ATP’s
Two types of fermentation:
Lactic acid Fermentation
Alcoholic Fermentation

24. Lactic acid Fermentation
Lactic acid fermentation occurs in muscle cells during strenuous exercise when a lot of energy is required and oxygen is scarce (oxygen debt).
Glucose  pyruvic acid  lactic acid + ATP
The lactic acid is transferred from the muscle cells to the liver where it will be converted back into pyruvic acid
The build up of lactic acid in the muscles is what causes them to be fatigued and sore.

25. Alcoholic Fermentation
Yeast and some bacteria cells are capable of alcoholic fermentation during which glucose is broken down to release CO2 and ethyl alcohol
Glucose  pyruvic acid  alcohol + CO2 + ATP
The bubbles formed by the CO2 make bread rise
The alcohol released turns grape juice into wine

26. Photosynthesis vs. Cellular Respiration
Stores Energy as glucose
Releases Energy in glucose
Occurs in Living Cells
Uses an Electron Transport Chain
Occurs in Plant Cells
Occurs in Animal Cells
Releases Oxygen
Releases Carbon Dioxide
Creates Energy           
Neither!

27. Aerobic Respiration
Process by which cells use oxygen to break down organic molecules, with the release of energy that can be used for biological work
A sequence of 30+ chemical reactions;
Breaks down fuel molecules – most common, glucose
Ultimately, it releases energy, carbon dioxide, and water