PHOTOSYNTHESIS:

Photosynthesis overview:• Performed by PLANTS ONLY!• All photosynthesis occurs in the chloroplast!

• Making sunlight into energy and oxygen• 6 CO2 + 6H2O + Light energy C6H12O6 (glucose)+ 6O2

• Occurs in 2 Steps Light dependent & Light Independent:• Light dependent uses sunlight to make energy!• Occurs in the Thylakoid membrane

• Light Independent uses the Calvin Cycle to make glucose!• Occurs in the Stroma

Where does Photosynthesis occur?:• Photosynthesis occurs in the chloroplasts!• Thylakoid = Membranous sacs that hold chlorophyll• Stroma = Dense fluid that fills the chloroplast

Photosynthesis occurs in 2 Steps:• 1.) Light-dependent reactions 2.) Light-independent reactions

Step 1: Light- dependent Reactions• Sunlight drives light-dependent reactions (rxns)• Take place in the Thylakoid of the chloroplast

• 2 Phases of Light-dependent rxns:

Light-dependent Reactions:

•As sunlight enters, it’s energy is transferred to electrons by splitting water molecules.

•Light-dependent reactions have 2 phases:Occurs 1st: In photosystem II electron energy is used to attach phosphates (to make ATP)

Occurs 2nd: In photosystem I electron energy bonds Hydrogen atoms NADP+ (to make NADPH)

• Both of these are produced in the Thylakoid membrane!!

• O2 is released as a byproduct (This is the air we breathe!!!)

Photosystems I & II:

Excreted as WASTE

Photosystem II (PSII):

• Lumen = Filling inside the thylakoid membrane• H+ pumped in by protein• H+ diffuses out of cell

through ATP synthase• Makes energy to create ATP

Diffusion out “turns wheel”

Lumen

Photosystem I (PSI):• Occurs in the Thylakoid Membrane• Electron is excited and used to power special molecule• This special molecule attaches H+ to NADP+ to form NADPH.

Photosystems I & II:

Excreted as WASTE

Light Independent Reactions:

• 1.) Light Dependent 2.) Light Independent

The Calvin Cycle:

• ATP and NADPH used (NO LIGHT USED)

• Takes place in stroma