1 9/19/2015 ph to synthesis Photosynthesis

2 9/19/2015 Flag

3 9/19/2015 Green Maple Leaf

4 9/19/2015 Green shores

5 9/19/2015 Chlorenchyma cells Stoma Chloroplast Site of Photosynthesis in Plants

6 9/19/2015 Photosynthesis n Light reactions (require light) –Photochemistry n Dark reactions (light not required) –Carbon fixation

7 9/19/2015 Overview of Photosyntheis

8 9/19/2015 Conjugated double bonds Chlorophyll

9 9/19/2015 Light reaction chl = chlorophyll A = electron acceptor chl chl * (excited form) chl * + A chl + + A - Light

10 9/19/2015 Light harvesting in a photosystem Primary electron acceptor Photon Light harvesting centre (antenna) Reaction centre e-e-

11 9/19/2015 Light reactions n Electrons are ejected from chlorophyll in reaction center n Energy from excited electrons is used –to pump protons (H + ) across a membrane – to reduce NADP + n Proton motor force (PMF) across membrane drives ATP synthesis

12 9/19/2015 Stroma Lumen of thylakoid Reaction center e donor e acceptor When we turn on the lights... Light Reactions

13 9/19/2015 Stroma Lumen of thylakoid Reaction center e donor e - acceptor + e- separation charge +++ Photons

14 9/19/ Stroma high pH lumen low pH H + H + H + H + H + H + H + Proton pump ADP ATP PMF ATP'ase

15 9/19/2015 Two modes of photosynthetic electron transport n Cyclic (purple bacteria- old) n Non-cyclic (the more recent mode) 1 = reaction centre 2 = quinones (e - transport) 3 = proton pump (cytochromes) 4 = cytochrome 5 = ATP’ase or CF 0 CF 1 complex

16 9/19/ Cytosol Exterior H + H + H + H + H + H + Light ATP ? H Cyclic electron transport (in purple bacteria)

17 9/19/2015 Non-cyclic electron transport uses TWO photosystems n The old one, PS I (p700nm) and n A more recent one, PS II (p680 nm)

18 9/19/ H + H + H + H + H + H + Light ATP ? H + PS II PS I e e H2O 2H+1/2 O2 NADP + + H + + 2e - NADPH Non Cyclic Electron Transport

19 9/19/2015 z Non-cyclic e - flow

20 9/19/2015 Cyclic electron Flow cyclic e - flow

21 9/19/2015 Logistics of chemiosmosis (mito) (chloroplast) (mitochondrion)

22 9/19/2015 Thylakoid Membrane Thylakoid space Stroma

23 9/19/2015 n Calvin & colleagues n Applied radioisotopically labelled carbon ( 14 C) to algae (in light) n Killed them n Separated the labelled products by chromatography n Determined the pathway of carbon in photosynthesis Dark Reactions of Photosynthesis

24 9/19/2015 Calvin Cycle

25 9/19/2015 Efficient Saves water too! C4 photosynthesis n Uses compartmentation of leaf n Two C-fixation steps (one is temporary) n Shuttles CO 2 to inner compartment n Fixes CO 2 by conventional C3 photosynthesis

26 9/19/ Bundle sheath 1. Mesophyll CO 2 C3+ CO 2 C4 CO 2 C3 ATP ADP (low conc.) (high conc.) C4 Anatomy

27 9/19/2015 C4 Pathway C 4 -photosynthesis

28 9/19/2015 C4 vs CAM Pathway C4C4 CAM Separation in space Separation in time

29 9/19/2015 Outer membrane Inner membrane Inter-membrane space 1. Stroma 2. Thylakoid space 3. Thylak. membrane What happens at 1,2 & 3? Question??

30 9/19/2015 Photosynthesis: Overview

31 9/19/2015 Like life, our atmosphere is e vol vi n g n Atmosphere....the dynamic gaseous boundary layer between our planet and space The Atmosphere was (and is being) created by photosynthesis... oxygen, ozone (derived from oxygen), CO 2 fixation are all regulated by photosynthesis.

32 9/19/2015 The End