1. Photosynthesis and Respiration
CELL ENERGY
Photosynthesis and Respiration

2. What are the green organelles inside the leaf cells?.
What is the function (job) of the chloroplast?

3. Chemical Energy and ATP
Energy = ability to do work
Energy comes in different forms (light, heat, electricity)
Cells need energy to do work
Cell energy comes from ATP (adenosine triphosphate)
Consists of adenine, a 5-carbon sugar and THREE phosphates
Phosphates are the key to ATP’s ability to store and release energy

4. Examples of ATP in action
Active transport
Protein pumps in cell membrane need ATP
Movement
Muscle contractions
Protein synthesis

5. Storing and Releasing Energy
Cells release energy from ATP when the bond between the second and third phosphate groups is broken
Phosphate released = energy released
ATP minus a phosphate group = ADP

6. Storing and Releasing Energy
ADP (adenosine diphosphate) can be recharged by adding another phosphate group to become ATP again
Phosphate gained = energy stored
Cells regenerate ATP from ADP by using energy in food like glucose

7. Quick Check Where is the energy stored in the molecule of ATP?
How would you change the figure to show a molecule of ADP?

8. What is the connection between the food you eat and ATP?
Cells do not keep a lot of ATP
Food is digested and converted into ATP
Different foods give different amounts of ATP
Carbohydrate = 36 ATP
Lipid = 146 ATP
Proteins = broken down to make other proteins, not energy!!!!
Plants use photosynthesis to produce the carbs so their cells can get ATP

9. LIGHT Energy Mixture of different wavelengths (color)
Can be absorbed, transmitted or reflected
Absorbed energy can be used for photosynthesis
Reflected light is not used for photosynthesis
Absorbed by pigments (chlorophyll) in plant cell chloroplasts

11. Quick Check…look at the light absorption spectrum on the previous slide
What color light is least absorbed?
What color(s) of light are most absorbed?
What color of light can be used for photosynthesis?
How would a plant grow if only given green/yellow light?

12. CHLOROPLASTS

13. CHLOROPLASTS
Thylakoids = photosynthetic membranes (contain chlorophyll)
Arranged in stacks called grana
Stroma = space around the thylakoids

15. High-Energy Electron Carriers
Chlorophyll absorbs light
Absorption of light produces high-energy electrons
Electrons picked up by NADP+ to become NADPH
NADPH carries the high-energy electrons to chemical reactions elsewhere in the cell

16. Photosynthesis – BIG PICTURE
Multi-step process
Energy from the sun is used to convert water and carbon dioxide (reactants) into high energy sugars and oxygen (products
Plants then use the sugars to make ATP (cell respiration…stay tuned)

17. Photosynthesis - Details
Light dependent reactions
INPUT= sunlight, water, chlorophyll
OUTPUT = oxygen (waste), ATP, energy carriers (NADPH)
LOCATION = thylakoid

18. Photosynthesis - Details
Light Independent reactions (a.k.a. Calvin Cycle)
INPUT– carbon dioxide, energy carriers from light reactions
OUTPUTS – sugar (carbohydrate) and water
LOCATION - stroma