Photosynthesis

What is Photosynthesis? The process where plants use energy from

the sun to rearrange water molecules and carbon dioxide molecules to form sugars (mainly glucose) and oxygen molecules

Plants DO NOT change sunlight into energy!!

The Chemistry of Photosynthesis

6CO2 + 6H2O ------------ > C6H12O6 + 6O2

CO2 is carbon dioxide

H2O is waterC6H12O6 is glucose

O2 is oxygen

Chlorophyll

Sunlight

The Chemistry of Photosynthesis

6CO2 + 6H2O ------------ > C6H12O6 + 6O2

CO2 is carbon dioxide

H2O is waterC6H12O6 is glucose

O2 is oxygen

Chlorophyll

Sunlight

The Role of Sunlight in Photosynthesis

Sunlight is made of different energies (colors) of light

Remember ROYGBIV from elementary school?

Chlorophyll absorbs the red, blue and violet parts of sunlight and stores the energy of those wavelengths.

The Role of Chlorophyll Chlorophyll is a chemical pigment (color)

that absorbs certain wavelengths of sunlight (especially red, blue and indigo)

The energy that is absorbed is given to the electrons of the chlorophyll molecule

These high energy electrons supply the starting energy for photosynthesis

Inside the Chloroplast Sac-like photosynthetic membranes called

thylakoids Sacs are stacked into structures called

grana Space between grana called stroma Proteins in thylakoids arrange chlorophyll

and other pigments into groups called photosystems

Inside the Chloroplast

Overview of Photosynthesis

Photosynthesis Has Two Steps Light dependent reaction that requires

sunlight Light independent reaction that does not

require sunlight; can occur during daytime as well as at night

Light Dependent Reaction dependent reaction that requires sunlight Water is split into hydrogen ions, oxygen

gas, and electrons Hydrogen ions are actively transported to

interior of thylakoid membrane Electrons are energized, stored in NADPH Oxygen gas diffuses out of the leaf

Dark Reaction Uses ATP and NADPH to produce high

energy sugars Uses 6 carbon dioxide molecules Results in sugars and other molecules Costs ATP and NADPH molecules

1. What are the reactants in photosynthesis? What are the products?

2. What wavelengths of light are absorbed by chlorophyll?

3. Why do green plants look green?

4. What part of the chlorophyll molecule actually absorbs the energy from the sun?

5. Define the following terms: thylakoid, grana, stroma, photosystem

6. What are the products of the light reaction phase of photosynthesis?

7. What are the products of the dark reaction phase of photosynthesis?