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Photosynthesis Biophysical Seminar December 2. Bence Ferdinandy

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Presentation on theme: "Photosynthesis Biophysical Seminar December 2. Bence Ferdinandy"— Presentation transcript:

1 Photosynthesis Biophysical Seminar 2011. December 2. Bence Ferdinandy
and some generally interesting facts about plants and whatnot Bence Ferdinandy Physics MSc II.

2 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Introduction 5 C + CO2 -> 2* 3C Adenozin trifoszfát Nikotin-adenin dinukleotid Bence Ferdinandy – Biophysics Seminar december 2.

3 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Introduction 5 C + CO2 -> 2* 3C Adenozin trifoszfát Nikotin-adenin dinukleotid Light phase binding of energy emission of oxigen Dark phase binding of CO2 sugar synthesis Bence Ferdinandy – Biophysics Seminar december 2.

4 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Outline of the talk The anatomy of Photosynthesis The Light phase The Dark phase Problems: photorespiration The efficiency of photosynthesis 5 C + CO2 -> 2* 3C Adenozin trifoszfát Nikotin-adenin dinukleotid Bence Ferdinandy – Biophysics Seminar december 2.

5 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
The plant cell (EM pic) 5 C + CO2 -> 2* 3C Adenozin trifoszfát Nikotin-adenin dinukleotid Bence Ferdinandy – Biophysics Seminar december 2.

6 The plant cell (cartoon)
Bence Ferdinandy – Biophysics Seminar december 2.

7 Endosymbiothic theory
Our ancestor protista ate bacteria like things: mithochondria and chloroplast Evidence: double membrane own DNA lot of things similar to bacteria they replicate separately (we get our mother’s) We are not alone in our own cells! Shocking piece of information Bence Ferdinandy – Biophysics Seminar december 2.

8 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Chloroplast (EM pic) P M Grana (thylakoid membrane) Lamella (thylakoid membrane) Bence Ferdinandy – Biophysics Seminar december 2. .

9 Chloroplast (cartoon)
Bence Ferdinandy – Biophysics Seminar december 2.

10 Purpose of the light phase: high energy molecules
ATP: Adenosine triphosphate Very important, (almost) everything works with it. Made in mitchondria also. NADPH: Nicotinamide adenine dinucleotide phosphate Bence Ferdinandy – Biophysics Seminar december 2.

11 Light phase I. (the electron transportchain)
Bence Ferdinandy – Biophysics Seminar december 2.

12 Light phase I. (the electron transportchain)
„OUTSIDE” „INSIDE” Bence Ferdinandy – Biophysics Seminar december 2.

13 Light phase I. (the electron transportchain)
Bence Ferdinandy – Biophysics Seminar december 2.

14 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
The heart of it all: the Photosystem What happens here? Bence Ferdinandy – Biophysics Seminar december 2.

15 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Photosystem II Quite a beauty if ya ask me. Bence Ferdinandy – Biophysics Seminar december 2.

16 The light harvesting complex of the Photosystems
The harvesting complex: Energy transfer with FRET Special pair Chlorophyll-A molecule Bence Ferdinandy – Biophysics Seminar december 2.

17 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
One photon excites one electron Bence Ferdinandy – Biophysics Seminar december 2.

18 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
The electron is passed to a plastoquinone One PQ can take two electrons Bence Ferdinandy – Biophysics Seminar december 2.

19 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Plastoquinone takes up two protons from the stroma („outside”) Bence Ferdinandy – Biophysics Seminar december 2.

20 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Plastoquinone gives the two electrons to cytochrome And the two protons to the lumen („inside”) Bence Ferdinandy – Biophysics Seminar december 2.

21 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
PSII lost two electrons: it splits water to get electrons, one H2O = e- Risky! 2 H2O = O2 + 2 p+ -> more protons „inside” Bence Ferdinandy – Biophysics Seminar december 2.

22 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Cytochrome transfers the two electrons to plastocyanin Two more protons are pumped to the lumen („inside”) Bence Ferdinandy – Biophysics Seminar december 2.

23 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Plastocyanin takes the two electrons to PSI The electrons are now ground state: their energy lost in the transfer and proton pumping Bence Ferdinandy – Biophysics Seminar december 2.

24 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Electrons are excited again and transfered to the the Ferredoxin NADP Reductase by ferredoxin Bence Ferdinandy – Biophysics Seminar december 2.

25 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
The FNR puts the energy of the electrons into NADPH Bence Ferdinandy – Biophysics Seminar december 2.

26 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Now there’s a concentration gradient of protons, so the protons go back „outside” through the ATP synthase. Bence Ferdinandy – Biophysics Seminar december 2.

27 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
The energy of the gradient is stored in ATP. ATP synthase is like a turbine and is rotated by the proton flow. Bence Ferdinandy – Biophysics Seminar december 2.

28 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Light phase II. Bence Ferdinandy – Biophysics Seminar december 2.

29 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Light phase III. 2 H2O , 4 photons 2 NADPH , 3 ATP , 1 O2 12 protons pumped Bence Ferdinandy – Biophysics Seminar december 2. .

30 Absortion spectrum of chlorophyll
Bence Ferdinandy – Biophysics Seminar december 2.

31 Excitation levels of chlorophyll
light Bence Ferdinandy – Biophysics Seminar december 2.

32 Excitation levels of chlorophyll
Fast energy loss S2 photosynthesis S1 T1 S0 light Bence Ferdinandy – Biophysics Seminar december 2.

33 Excitation levels of chlorophyll
Fluorescence S3 Fast energy loss Phosphorescence S2 photosynthesis S1 T1 S0 light Bence Ferdinandy – Biophysics Seminar december 2.

34 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Dark phase I: RuBisCO Ribulose-1,5-bisphosphate carboxylase oxygenase: The most abundant protein on Earth. Bence Ferdinandy – Biophysics Seminar december 2.

35 Dark phase II: Calvin-cycle
RuBisCO RuBP (5C) + 3 CO pc. 6C pc. 3PGA (3C) 13 steps, energy consuming process (Calvin cycle) 1 G3P (3C) 3 RuBp 2 G3P glucose (6C) the energy used during this: 12 NADPH 18 ATP Ribulose-1,5-bisphosphate carboxylase oxygenase Foszfoglicerinsav (3pga) Glyiceraldihed 3 foszfát 24 photons Bence Ferdinandy – Biophysics Seminar december 2.

36 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Calvin cycle Bence Ferdinandy – Biophysics Seminar december 2.

37 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Photorespiration RuBisCO can take O2 as substrate, creates useless product (concentration dependent) reversing the product needs energy, process loses C it is done by the photorespiration complex (chloroplast + mitochondrion + peroxisome) types of photosynthesis: C3, C4, CAM C4: Kukorica, cukorrépa Cam: orchidea Bence Ferdinandy – Biophysics Seminar december 2.

38 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
C3 Photosynthesis Typical (85%) Just explained how it works Fixes CO2 into C3 product Inefficient in hot and dry circumstances, because leaves „close” (don’t lose water, can’t take up CO2 Bence Ferdinandy – Biophysics Seminar december 2.

39 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
C4 Photosynthesis Spatial separation Fixes CO2 in outer cell with PEP (another ensym) to C4 product C4 into CO2 in inner cell Calvin cycle in inner cell RuBisCo doesn’t meet high concentration of oxygen Example: sugarcane, corn Bence Ferdinandy – Biophysics Seminar december 2.

40 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
CAM Photosynthesis Temporal separation, 1 cell Fixes CO2 with PEP during night while Calvin cycle is not going Closes cell during day and does Calvin cycle Example: Cactus, pineapple Bence Ferdinandy – Biophysics Seminar december 2.

41 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Efficiency I. Loses of energy during the whole process: ~30% - cross section ~47% - limited absorbtion range ~24% - uses energy of red quanta only ~68% - during the glucose production ~35-45% - photorespiration and such this estimate gives 5-6% efficiency Bence Ferdinandy – Biophysics Seminar december 2.

42 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Efficiency II. Theoretical: 30% (including the energy loss of chemical reactions Laboratory conditions: 25% Natural conditions: in Death Valley (winter evening primrose): 8% sugarcane: 7% (remember, it’s C4) most crops: 1-4 % This 1-7% is also used to upkeeping, growing, reproduction ligetszépe Bence Ferdinandy – Biophysics Seminar december 2.

43 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
Efficiency III. Comparison with solar panels: theoretical: 86% laboratory: > 40 % commercial (cheap/not so cheap): ~6% / 15-20% BUT: the plant is a self-replicating, self-maintaining solar cell, and enviroment friendly (no rare elements needed) ligetszépe Bence Ferdinandy – Biophysics Seminar december 2.

44 Bence Ferdinandy – Biophysics Seminar 2011. december 2.
What we have learned the anatomy of the photosynthetic apparatus: chloroplast light phase: electron transport chain, water splitting, O2 making generates high energy molecules, uses proton gradient dark phase: CO2 fixation with RuBisCO + energy = glucose photorespiration: RuBisCO can fix O2 as well -> C3, C4, CAM paths efficiency: below 10% Bence Ferdinandy – Biophysics Seminar december 2.

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