Textbook References 3.3 – pg – pg Nelson Biology 12

Textbook References 3.3 – pg

 Z-protein splits H 2 O into: 2 protons (H + ) 2 electrons (e - ) ½O 2.  Where do each of these go? Oxygen _______________ Protons _______________ Electrons ______________ ???

 1 electron goes to PSII Enters ground state  In your textbook it does say 2, but that’s because the whole electron flow occurs twice

 Chlorophyll Molecules Ground State Excitation & Fluorescence Reaction center (chlorophyll a)  P700 in PSI, P680 in PSII Primary Electron Acceptor

Refer to page of your textbook

 Primary electron acceptor (pheophytin) Redox reactions Electron carrier Plastiquinone takes excited electron

 Q cycle Plastiquinone along with a protein b6-f cytochrome complex Pumps 4 protons per 2 electrons  B6-f complex with plastoquinone create a complicated mechanism to introduce 4 protons into the lumen (you’ll learn this in university!)

 Q cycle Plastocyanin takes excited electron Transfer electron to PSI (back in ground state)

 Primary electron acceptor (pheophytin) Redox reactions Electron carrier ferredoxin takes excited electron

 NADPH production Protein NADP Reductase uses 2 electrons to reduce NADP + + H +  NADPH

 ATP production Protons accumulate to create gradient ATPase complex pumps proton out Movement allows ADP + P i  ATP

 NADPH production Protein NADP Reductase uses 2 electrons to reduce NADP + + H +  NADPH  ATP production Protons accumulate to create gradient ATPase complex pumps proton out Movement allows ADP + P i  ATP  The products formed, ATP and NADPH proceed to the Calvin Cycle To review the entire process, review pg of your textbook

 Some cases where PSI does it’s own thing

 Why do you think this would happen? What are its advantages and its disadvantages?

Textbook References 3.4 – pg

 C3 photosynthesis AKA: Calvin Cycle Most plants go through this form Optimal temperature: (15 o C – 25 o C)  Photorespiration O2 bonds to Rubisco instead of CO2 Rubisco + O2  PGA (3 Cs) + glycolate (2 Cs) 2 glycolate  CO2 + G3P (returned to Calvin Cycle) C3 plants continually do this and lose 20-50% of carbon

 C4 photosynthesis AKA: “Hatch-slack pathway” A CO 2 delivery system, More CO 2 to outcompete O 2 for rubisco in interior cells Oxaloacetate and malate are the CO 2 transporters

The upper half is the C4 photosynthesis The lower half is the Calvin Cycle Please refer to Pg of your textbook

C3 PhotosynthesisC4 Photosynthesis Optimal Temperature 15 o C-25 o C Energy Cost Uses up 18 ATP Examples of plants Soybeans, Kentucky bluegrass, sunflowers, etc. 30 o C-47 o C Uses up 30 ATP Tropical plants; Sugar cane, maize, corn

 CAM – Crassulacean Acid Metabolism Stomata open at night to take in CO2 CO2 incorporated into C4 organic acids Organic acids stored in vacuoles until morning Organic acids release CO2 to enter Calvin Cycle Please refer to pg of your textbook

 C4 plants have carbon fixation and Calvin cycle in different compartments Carbon fixation in mesophyll cells Calvin cycle in bundle-sheath cell  CAM plants have processes occur in same compartment but different times Carbon fixation into organic acids at night Calvin Cycle during the day