1. 4.7 Photosynthesis Overview
Unit 4: Cell Energy
4.7 Photosynthesis Overview

2. Photosynthesis
Uses energy from sunlight to convert water and carbon dioxide (reactants) into high energy sugars and oxygen (products)

3. Photosynthesis Sunlight is the ultimate energy for all life on Earth
Plants then use sugars to produce complex carbohydrates and provide energy
Plants store energy from the sun in the chemical bonds of sugars
Chemical energy is released as ATP during cellular respiration BOTH IN PLANT AND ANIMAL CELLS

4. Overall Equation

5. Sunlight
Sunlight is a mixture of different wavelengths our eyes perceive as white
Colors include red, orange, yellow, green, blue, indigo, and violet
The sun’s energy travels to Earth as light

6. Chloroplast
Organelle where photosynthesis occurs

7. Structure Contain an inner and outer membrane
Thylakoid: saclike photosynthetic membranes
Grana: Interconnected stacks of thylakoid
Stroma: Fluid outside the thylakoid

8. Thylakoid Membrane
Thylakoid Space
Granum
Stroma
Outer Membrane
Inner Membrane

9. Pigments
Pigments are light-absorbing molecules that gather the sun’s energy
Pigments are located in the thylakoid membranes

10. Chlorophyll A plant’s principle pigment
Chlorophyll absorbs visible light especially well
Chlorophyll absorbs blue-violet and red wavelengths of light best
Chlorophyll reflects green wavelengths, causing them to appear green

11. Fall Colors
Plants also contain red and orange pigments, such as carotene, that absorb light in other regions of the spectrum.
As temperatures drop later in the year, chlorophyll pigments break sown first, leaving red and orange pigments to be seen

12. Reactions in Photosynthesis
Light Dependent Reactions
Light Independent Reactions
Require direct involvement of light
Use sun’s energy to produce ATP
Takes place in the thylakoids
Water is required as a sources of electrons and hydrogen ions
Oxygen is released
No Light is required
ATP and NADPH are used to make sugars
Takes place in the stroma
Carbon dioxide is required

13. Questions In which organisms does photosynthesis occur?
In which organisms does cellular respiration occur?
Why do leaves change colors in the fall?
What does photosynthesis produce?