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 CO H 2 O + sunlight  Glucose + 6 O 2

The Chloroplast- Where Photosynthesis Happens The insides of leaf cells can contain a half million chloroplasts per square mm of leaf surface STROMAGRANA THYLAKOID THYLAKOIDPIGMENTS

Photosynthesis has: “Light Reactions” take place in the GRANA where electrons (e-) are excited by the sun’s energy and through the splitting of H 2 O “Dark Reactions” take place in the STROMA and are where the glucose is made.

The Light Reactions light energy converted to chemical energy (ATP and NADPH) Location: Thylakoid membranes of grana inside chloroplast Reactants- Sunlight + water Products- ATP, O 2, H NO SUGAR IS PRODUCED

The The Light Reactions GRANA CHLOROPLAST

The Light Reactions: Photolysis Sunlight excites an electron and water is split. O 2 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

 Produces complex carbs ( glucose, startch, cellulose) Happens in stroma Reactants: CO 2 (from atmosphere) ATP (from light reactions) Hydrogen (from NADPH) Product: Glucose! Sugar! FOOD!

Dark Reactions (Inside chloroplast not in grana)  CO 2 enters the cell from the air.  CO 2 combines with Hydrogen from the light reactions to form carbohydrates (like sugar and starch)

The Calvin Cycle

Photosynthesis Essay Have 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.