+

Photosynthesis: Converting sunlight into chemical energy

Students who demonstrate understanding can:HS-LS1-5: Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.

+Where does the oxygen (O2) we

breathe come from?

O2 is produced by different kinds of bacteria, algae, and plants (including trees) during photosynthesis.

About 25% of O2 comes

from land plants.

Most of Earth’s O2 comes from the ocean. Released from tiny ocean

plants called, phytoplankton.

+Autotrophs and Photosynthesis

Called “self feeders” or ”producers”.

Organisms that can produce their own food using light, water, carbon dioxide, or other chemicals.

Examples of autotrophs: green plants, some algae, few bacteria.

Most autotrophs use photosynthesis to make their food.

+Overview of Photosynthesis

Light energy gets converted into chemical energy.

Chemical energy is stored in the form of glucose (sugar).

Carbon dioxide, water, and sunlight are used to produce carbohydrates and oxygen.

Occurs in two stages: Light Dependent Reactions Light Independent Reactions

NASA: Seeing Photosynthesis From Space

+Where Does Photosynthesis Take

Place in the Cell?

+Chloroplast Anatomy:

+Closer Look at Chloroplast

Structures Chlorophyll:

Allows plants to absorb energy from light

Gives leaves their green color

Membrane Envelope: Inner and outer membranes Protects and keep chloroplast

structures enclosed.

Thylakoid membrane: Internal membrane system Flattened sac-like membrane

structures called thylakoids Serve as the sites of

conversion of light energy to chemical energy.

Granum Dense layered stacks of

thylakoid sacs Sites of conversion of light

energy to chemical energy.

Stroma Dense fluid within the

chloroplast Lies inside the envelope but

outside the thylakoid membrane

Site of conversion of carbon dioxide to carbohydrates

+

Two Processes of Photosynthesis

Location: Thylakoid Membrane

Reactants: Sunlight and water (H2O)

End Products: ATP, NADPH, and O2

Also called “Calvin Cycle” or Dark Reactions

Location: Stroma

Reactants: ATP, NADPH, and O2

End Products: Glucose

Light Dependent Reactions Light Independent Reactions

Remember: Cells use ATP for energy NADPH is a cofactor in reactions that acts as a reducing agent

+How Does It All Work?

+Photosynthetic Equation

Photosynthesis can be represented using a balanced chemical equation:

+Why is photosynthesis essential to

life on Earth?

Well..

Life can be sustained in plants.

Plants provide oxygen for humans.

We BREATHE oxygen!

Without oxygen we cannot survive!