Unit 3 – Lecture 8

Photosynthesis Photosynthesis: the process used by autotrophs which changes solar energy, water [H 2 O], and carbon dioxide [CO 2 ] into glucose [C 6 H 12 O 6 ] and oxygen [O 2 ] Equation for Photosynthesis: E + H 2 O +CO 2  C 6 H 12 O 6 + O 2

Photosynthesis – cont’d takes place in the chloroplasts of the cell “chloro” – green [pale green] contain green pigment, chlorophyll “phyll / phyllos” = leaf chloroplasts are FILLED with chloroPHYLL

Light Dependent Reactions sunlight transfers a photon of solar energy to chlorophyll in the chloroplast which exites an electron e - gets knocked out of placement

Light Dependent Rxns – cont’d e - travels down the Electron Transport Chain [also called Electron Transport System] as e - travels, it loses E that E splits H2O [called photolysis] into Oxygen [O2] Gas and Hydrogen [H + ] Ions which is released into the atmosphere

Light Dependent Rxns – cont’d … Hydrogen [H + ] Ions… which either bonds with NADP+is pumped into the thylakoid to form NADPH to form a gradient of which goes to the light charge AND independent reactions concentration [called electrochemical gradient]

Light Dependent Rxns – cont’d …ElectroChemical Gradient… which causes the H+ ions to funnel through the ATP Synthase to form a small amount of ATP

Light Dependent Rxns – cont’d …to form a small amount of ATP… which goes on to the Light Independent Reactions

Summing it up… Equation: E + H 2 O +CO 2  C 6 H 12 O 6 + O 2 of the things in our equation…which things are input or formed in the light dependent reactions of photosynthesis? input: energy + water formed: oxygen gas

ATP Synthase Hydrogen Ions are pumped into the thylakoid membrane after water is split… ions form electro- chemical gradient ions funnel through ATP synthase turns “crank” energy from turning makes ADP+P into ATP

Light Independent Reactions aka Dark Reactions or Calvin Cycle can occur in the LIGHT or the dark [light rxns can only occur when there is sunlight]

The Calvin Cycle

Light Indep. Rxns – cont’d What you NEED to know: can occur with or without light present composed of the calvin cycle Carbon dioxide (CO 2 ) is taken in and combined with the H + from NADPH (using ATP) to make Glucose (C 6 H 12 O 6 ). leftovers – ADP and NADP+ go back to light dependent reactions

Summing it up… Equation: E + H 2 O +CO 2  C 6 H 12 O 6 + O 2 of the things in our equation…which things are input or formed in the light INdependent reactions of photosynthesis? input: carbon dioxide [and some water] formed: glucose

Overview - Photosynthesis solar energy [photon] ATP NADPH NADP + ADP H2OH2O a little bit of H 2 O CO 2 O2O2 C 6 H 12 O 6 thylakoids stroma

IMPORTANT!! Be sure to know: what goes in where that came from what goes out where that’s going