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Energy Harvesting and Usage Photosynthesis and Cellular Respiration.

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Presentation on theme: "Energy Harvesting and Usage Photosynthesis and Cellular Respiration."— Presentation transcript:

1 Energy Harvesting and Usage Photosynthesis and Cellular Respiration

2 What you must know Photosynthesis Products and reactants for each stage Light Dependent Photosystem II Photosystem I Light Independent (Calvin Cycle) Where each stage occurs CAM versus C4 strategies for plants Chlorophyll a, b, and carotenoids Respiration Products, reactants, location, and order of processes Glycolysis Kreb (Citric Acid) Cycle Electron Transport Chain Fermentation Number of ATP produced

3 Must Knows – cont. Proteins and Molecules Rubisco RuBP ATP Synthase Co-enzyme A ATP, ADP, AMP NADH FADH2 NADPH Equations Overall Photosynthesis Overall Respiration

4 Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf A typical mesophyll cell has 30–40 chloroplasts The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast); thylakoids may be stacked in columns called grana Chloroplasts also contain stroma, a dense fluid Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

5 Fig. 10-3b 1 µm Thylakoid space Chloroplast Granum Intermembrane space Inner membrane Outer membrane Stroma Thylakoid

6 Tracking Atoms Through Photosynthesis: Scientific Inquiry Photosynthesis can be summarized as the following equation: 6 CO H 2 O + Light energy  C 6 H 12 O O H 2 O Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7 The Two Stages of Photosynthesis: A Preview Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part) The light reactions (in the thylakoids): Split H 2 O Release O 2 Reduce NADP + to NADPH Generate ATP from ADP by photophosphorylation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

8 The Calvin cycle (in the stroma) forms sugar from CO 2, using ATP and NADPH The Calvin cycle begins with carbon fixation, incorporating CO 2 into organic molecules Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9 Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i +

10 Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2

11 Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2 Calvin Cycle CO 2

12 Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2 Calvin Cycle CO 2 [CH 2 O] (sugar)

13 Fig Light Reactions: Photosystem II Electron transport chain Photosystem I Electron transport chain CO 2 NADP + ADP P i + RuBP 3-Phosphoglycerate Calvin Cycle G3P ATP NADPH Starch (storage) Sucrose (export) Chloroplast Light H2OH2O O2O2

14 Chlorophyll a is the main photosynthetic pigment Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15 Fig Wavelength of light (nm) (b) Action spectrum (a) Absorption spectra (c) Engelmann’s experiment Aerobic bacteria RESULTS Rate of photosynthesis (measured by O 2 release) Absorption of light by chloroplast pigments Filament of alga Chloro- phyll a Chlorophyll b Carotenoids

16 There are two types of photosystems in the thylakoid membrane Photosystem II (PS II) functions first (the numbers reflect order of discovery) and is best at absorbing a wavelength of 680 nm The reaction-center chlorophyll a of PS II is called P680 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

17 Photosystem I (PS I) is best at absorbing a wavelength of 700 nm The reaction-center chlorophyll a of PS I is called P700 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

18 P680 + (P680 that is missing an electron) is a very strong oxidizing agent H 2 O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680 +, thus reducing it to P680 O 2 is released as a by-product of this reaction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

19 Calvin Cycle Regenerates starting material Builds sugar from smaller molecules using ATP and NADPH 3 Phases Carbon fixation (uses rubisco) Reduction Regneration of the CO2 acceptor (RuBP)

20 CAM plants Photosynthetic adaptation to arid conditions Plants open stomata during the night and close during the day (reverse of other plants)

21 C4 Plants Plants that have an additional step before the Calvin cycle Incorporate CO2 in four-carbon compounds in mesophyll cells

22 Glycolysis Occurs in the cytoplasm Anaerobic reaction Requires 2 ATP Produces 4 ATP, 2 NADH, and 2 Pyruvate

23 Kreb Cycle (aka citric acid cycle) Aerobic process Occurs in mitochondria (matrix) Each turn of the cycle generates 1 ATP 3 NADH 1 FADH2 For each glucose molecule, there are 2 turns (total of 2 ATP, 6 NADH, and 2 FADH2)

24 Electron Transport Chain NADH and FADH2 are electron carriers which donate electrons to the chain which causes the formation of ATP Aerobic Process Cristae of mitochondria and intermembrane space Creates H2O Creates about 32 ATP Uses H+ gradient to drive ATP synthesis

25 Fig. 10-UN5

26 Fig INTERMEMBRANE SPACE Rotor H+H+ Stator Internal rod Cata- lytic knob ADP + P ATP i MITOCHONDRIAL MATRIX

27 Fermentation Glycolysis plus regeneration of NAD+ (for reuse in glycolysis) Occurs in Cytoplasm Anaerobic respiration Two types Alcohol Lactic acid Does not generate any ATP just electron carrier proteins


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