1. The Working Cell: Energy from Sunlight
Chapter 8
The Working Cell:
Energy from Sunlight

2. 8.1 Photosynthesis uses light
chloroplast: organelle where photosynthesis takes place
chlorophyll: chemical compound that gives green color
Green parts of plants
Chloroplasts concentrated in mesophyll cells
mesophyll: inner layer of tissue of a leaf
stomata: pores found on surface of leaf that allows gas and liquid exchange
CO2 enters; O2 exits
Veins carry water to leaves

3. Chloroplast Similar to mitochondria
Inner and outer membranes
stroma: thick fluid in inner membrane
thylakoids: many disk-shaped sacs
Each has a membrane surrounding an interior space
grana:stacks of thylakoids

4. 2 Stages of Photosynthesis
Light Reaction
Convert energy in sunlight to chemical energy
Calvin Cycle
“Light-independent”
Makes sugar from CO2

5. 8.2 Light Reactions
electromagnetic energy: travels in waves that can be compared to ocean waves onto a beach
Sunlight
wavelength: distance between 2 adjacent waves
Different in each form
Longest=radio (weakest)
Shortest= gamma rays

6. Electromagnetic Spectrum
electromagnetic spectrum: range of types of EM energy
Visible light between 400nm(violet) and 700nm(red)
UV has enough energy to damage cells
Specifically proteins and nucleic acids

7. Pigments pigments: a substances color due to chemical compounds
Light can be absorbed, transmitted or reflected
A chloroplast’s pigments absorb blue-violet and red-orange very well
Does not absorb green
Reflected or transmitted

8. Paper Chromatography Used to observe pigments in a green leaf
chlorophyll a: absorbs mainly blue-violet and red-orange and reflects mostly green
Major role in photosynthesis
chlorophyll b: “helper” absorbs mainly blue and orange and reflects yellow-green.
carotenoids: “helper”- absorbs mainly blue-green and reflects yellow-orange
Ex. carotein

9. Stages of Photosynthesis

10. The Light Reactions Convert energy in sunlight to chemical energy
1. Chlorophyll molecules(membrane of thylakoid) capture light energy
2. Captured energy used to remove electrons from water which splits into oxygen and hydrogen
3. Water’s electrons and H+ ions are used to make NADPH
4. Captured energy used to make ATP

11. Photosystems
photosystems: clusters of chlorophyll and other molecules in the thylakoid
Each contain a few hundred pigment molecules
Acts like a solar panel

12. The Calvin Cycle “Light- independent reactions”
Makes sugar from CO2 and H+ and electrons carried by NADPH
Enzymes located in stroma
ATP from light reactions provides energy
Requires ATP and NADPH