Cell Energy

Why do cells need energy?

How can cells store energy? A molecule called adenosine

triphosphate ATP

Energy is stored in ________________Chemical Bonds

Cell Energy

Why does ATP have so much stored energy?

ATP can be recycled.

Why worry about Photosynthesis?

Food chains begin with the SUN! Autotrophs are the

first level of the food pyramid.

Heterotrophs eat autotrophs

Carbon sinks

atmosphere

What is Photosynthesis? Process used by autotrophs to

change the sun’s energy into chemical energy stored in organic molecules.

Trapping energy from sunlight and using it to build food (complex carbohydrates)

Plants, protists (algae), bacteria

Pigments and Wavelength of Light

Equation for Photosynthesis

6 CO2 + 6 H2O + sunlight

Glucose + 6 O2

The Chloroplast- Where Photosynthesis

HappensThe insides of leaf cells can contain a half million

chloroplasts per square mm of leaf surface

STROMASTROMA

GRANAGRANA THYLAKOIDTHYLAKOID

PIGMENTSPIGMENTS

Photosynthesis has:

•“Light Reactions”

•take place in the GRANA where electrons (e-) are excited by the sun’s energy and through the splitting of H2O

•“Dark Reactions”

•take place in the STROMA and are where the glucose is made.

The Light Reactionslight energy converted to chemical energy

(ATP and NADPH)Location: Thylakoid membranes of grana inside chloroplastReactants- Sunlight + waterProducts- ATP, O2 , H

NO SUGAR IS PRODUCED

The

The Light Reactions

GRANA

CHLOROPLAST

The Light Reactions: Photolysis Sunlight excites an electron and water

is split. O2 is released into atmosphere

ATP is made as electron falls down the Electron Transport Chain

Excited electron produces NADPH.

Both ATP and NADPH will take go to the DARK SIDE.

The Light Reactions

Welcome…to the DARK side

Calvin Cycle

Calvin Cycle• Produces complex carbs ( glucose, startch, cellulose)•Happens in stroma•Reactants:

•CO2 (from atmosphere)

•ATP (from light reactions)• Hydrogen (from NADPH)

•Product: Glucose! Sugar! FOOD!

Dark Reactions(Inside chloroplast not in grana)

CO2 enters the cell from the air.

CO2 combines with Hydrogen from the light reactions to form carbohydrates (like sugar and starch)

The Calvin Cycle

Photosynthesis EssayHave you ever heard that the chloroplasts

produce glucose? This is how they work. It starts with sunlight hitting the chloroplast. The energy of the sunlight is captured by chlorophyll. This energy is used to split water into hydrogen and oxygen. The oxygen is released. This process is called the light reaction.

The hydrogen is used in the dark reactions. Carbon dioxide combines with the hydrogen through a series of reactions called the Calvin Cycle which makes glucose. This process is photosynthesis.