1. Picture Guide to Chapter 8
Photosynthesis

2. 8-1 Energy and Life

3. Objectives
Explain where plants get the energy they need to produce food
Describe the role of ATP in cellular activities

4. Q: Where does energy come from?
A: Our food, but originally the energy in food comes from the sun

5. Autotrophs
Make their own food

6. Heterotrophs
Cannot make their own food

7. Chemical Energy and ATP
The principal chemical compounds that cells use to store and release energy is called ATP adenosine triphosphate

8. Storing Energy ATP stores energy in the third phosphate
ATP is like a fully charged battery

9. Releasing Energy Q: How is the energy in ATP released?
A: Break bond between the second and 3rd phosphates 2
ADP

11. ATP Formation - Using Biomechanical Energy
Active Transport
Movement of organelles throughout cell
Synthesis of proteins and nucleic acids
Produce light
Blink of firefly caused by an enzyme powered by ATP

12. ATP Availability
Most cells only have enough ATP for a few seconds of activity
Why?
Not good at storing energy over the long term
Glucose stores 90 times the chemical energy of ATP
Cells generate ATP from ADP as needed by using the energy in foods like glucose

13. Photosynthesis
The process in which plants use the energy of sunlight to convert water and carbon dioxide into high energy carbohydrates – sugars and starches – and oxygen as a waste product

14. Photosynthesis

15. The Photosynthesis Equation
light
CO2 +
H2O
C6H12O6 + O2
(Carbon Dioxide)
(Water)
(Sun)
(Glucose)
(Oxygen)

16. Chlorophyll
The plants principal pigment, absorbs light energy in the blue-violet and red spectrum of visible light

17. Chlorophyll a and Chlorophyll b Absorption of Light by V B G Y O R

18. Because light is a form of energy…
Anything that absorbs light also absorbs the energy from that light
When chlorophyll absorbs light, much of the energy is transferred to electrons in the chlorophyll molecule, raising the energy level of these electrons
These high-energy electrons make photosynthesis work

19. 8-3 The Reactions of Photosynthesis

21. Thylakoids
Sac-like photosynthetic membranes arranged in stacks

22. Grana
Stacks of thylakoids

23. Stroma
The region outside the thylakoid

24. Scientists describe the reactions of photosynthesis in two parts
Light – dependent reactions (takes place in the thylakoid membranes)
Light – independent reactions (takes place in stroma)

26. Carrier Molecule
Compound that can accept a pair of high energy electrons and transfer them along with most of their energy to another molecule
Ex.) NADP+

28. Q: What does this do? NADP+ NADPH
A: this traps sunlight in chemical form

29. Light Dependent Reactions
Uses energy from light to produce
Oxygen gas
ATP
NADPH

30. Fig. 8-10

31. The Calvin Cycle
The ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes.
The Calvin cycle uses ATP and NADPH from light – dependent reactions to produce high energy sugars

32. The Calvin Cycle
These reactions don’t require light, therefore these reactions are called
Light – independent reactions

33. Fig 8.11

34. Factors Affecting Photosynthesis
Not enough water
Temperature
Light intensity