AP Biology Day 21. Friday, October 7, 2016

Transcription

1 AP Biology Day 21 Friday, October 7, 2016

2 Do-Now Group Discussion In your groups, discuss the 2014 FRQ prompt Discuss possible answers for each part Jot down your ideas as a group to help plan a response Revise your explanations until you have the BEST possible answer

3 Announcements Clear missing assignments! Study for Ch. 10 quiz & Ch test J Quarter 1 ends 10/14 à Retakes/missing work by Tuesday

4 CW/HW Assignments 7. Ch. 9 Practice FRQ 8. Ch. 10 Lecture Notes 9. Ch. 10 VCN PLANNER 1. Labs and logs MUST be turned in 2. Ch. 10 Video CN (1 video) 3. Study Ch Lab next Friday

5 EssenJal knowledge standards 2.A.1: All living systems require constant input of free energy 2.A.2: Organisms capture and store free energy for use in biological processes

6 FLT I will be able to: describe the structure of a chloroplast describe the the role of ATP and NADPH in the Calvin Cycle compare and contrast oxidative phosphorylation and photophosphorylation in chloroplasts By completing Ch. 10 Lecture Notes

7 Ch. 10: Photosynthesis

8 Energy = Life All living organisms must obtain energy in order to live Autotrophs = Produce their own energy via photosynthesis or chemosynthesis Heterotrophs = consume other organisms Ø They capture free energy present in carbon compounds produced by other organisms

9 Energy = Life Autotrophs make their own food and sustain themselves without eajng anything derived from other organisms Autotrophs are the producers of the biosphere, producing organic molecules (such as glucose) from CO 2 and other inorganic molecules Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules from water and carbon dioxide 9

10 Autotrophs = Producers (a) Plants (c) Unicellular protist 10 µm (e) Purple sulfur bacteria 1.5 µm (b) Multicellular alga (d) Cyanobacteria 40 µm

11 Review Living cells require energy from outside sources Energy flows into an ecosystem as sunlight and leaves as heat Photosynthesis generates O 2 and organic CHO molecules (used in cellular respirajon)

12 Energy Flow and Chemical Recycling in Ecosystems IN: Light Energy ECOSYSTEM CO 2 + H 2 O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic Molecules + O 2 OUT: Heat energy ATP ATP powers most cellular work

13 Chloroplasts Photosynthesis typically occurs in leaves Chlorophyll, a pigment found in chloroplasts, gives them their green appearance Chlorophyll absorbs visible light E, which is used to synthesize organic molecules such as glucose CO2 enters and O2 exits the leaf through microscopic pores called stomata 13

14 Chloroplast Structure

15 Chloroplast Structure Intermembrane space b/t inner and outer membranes 15

16 Chloroplast Structure Thylakoid= flaZened, membranous sacs Grana = stacks of thylakoids 16

17 Chloroplast Structure Stroma = dense fluid in the chloroplast 17

18 Chloroplast Structure

19 Chloroplast Chloroplasts probably evolved from cyanobacteria (photosynthedc bacteria) 19

20 Chloroplast Chloroplasts are found mainly in cells of the mesophyll (interior Dssue of the leaf) 20

21 Chloroplast A typical mesophyll cell has chloroplasts 21

22 Leaf cross section Vein Zooming in on the location of photosynthesi s in a plant Mesophyll Stomata CO 2 O 2 Chloroplast Mesophyll cell 5 µm

23 Pair-Share-Respond 1. What are photoautotrophs? 2. Describe the main structures of the chloroplast 3. What is the significance of a stomata? 4. What are cyanobacteria?

24 Recall: RespiraJon Review 6O 2 + C 6 H 12 O 6 à 6CO 2 + 6H 2 O + Energy This occurs in three main steps: Glycolysis Krebs/CA Cycle ETC Where does the glucose come from?? 24

25 Photosynthesis Overview Photosynthesis = energy transfer process that converts solar energy into stored chemical energy Photosynthesis provides the Earth with food and atmospheric oxygen 25

26 Photosynthesis Overview Photosynthesis can be summarized with the following equation 6CO 2 + 6H 2 O + Light E è C 6 H 12 O 6 + 6O 2 26

27 27 Recall

28 Photosynthesis Overview Photosynthesis is a redox reacjon: H 2 O is oxidized to O 2 CO 2 is reduced to C 6 H 12 O 6 28

29 Stages of Photosynthesis 1. The light dependent reacjons 2. The light independent reacjons (Calvin Cycle) 29

30 Stages 1. The light dependent reactions Occur within and across the thylakoid membrane H 2 O is split into hydrogen and oxygen (photolysis) The e - s hold the free energy from the light Through an ETC, light E is transformed into ATP and NADPH Generate ATP by photophosphorylation 30

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32 Stages 2. The light independent reactions (Calvin Cycle) Takes place in the stroma Forms C 6 H 12 O 6 from CO 2 using ATP and NADPH The Calvin Cycle begins with carbon fixation, which incorporates CO 2 into organic molecules and then reduction produces sugar 32

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34 Fig H 2 O Light NADP + ADP + P i Light Reactions Chloroplast

35 Light Reactions H 2 O Light NADP + ADP + P i Light Reactions ATP NADPH Chloroplast O 2

36 H 2 O CO 2 Light Light Reactions NADP + ADP + P ATP i Calvin Cycle NADPH Chloroplast O 2

37 Photosynthesi s H 2 O CO 2 Light Light Reactions NADP + ADP + P ATP i Calvin Cycle NADPH Chloroplast O 2 [CH 2 O] (sugar)

38 Pair-Share-Respond 1. Define photosynthesis 2. Why is photosynthesis considered to be a redox reacdon? Be specific 3. What are the two stages of photosynthesis and where do they take place? 4. IdenDfy two things that occur in the first stage.

39 The Nature of Sunlight Light is a form of electromagnejc energy, also called electromagnejc radiajon Like other electromagnejc energy, light travels in rhythmic waves Wavelength is the distance between crests of waves Wavelength determines the type of electromagnejc energy 39

40 The Nature of Sunlight The electromagnedc spectrum = the endre range of electromagnedc energy, or radiadon Visible light consists of wavelengths (including those that drive photosynthesis) that produce colors we can see Light also behaves as though it consists of discrete energy parjcles, called photons 40

41 Electromagnetic Spectrum 10 5 nm 10 3 nm 1 nm 10 3 nm 10 6 nm 1 m (10 9 nm) 10 3 m Gamma rays X-rays UV Infrared Microwaves Radio waves Visible light nm Shorter wavelength Higher energy Longer wavelength Lower energy

42 PhotosyntheJc Pigments: Light Receptors Pigments = substances that absorb visible light Different pigments absorb different wavelengths Wavelengths that are not absorbed are reflected or transmized Leaves appear green because chlorophyll reflects green light. We see reflected light. 42

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44 Why leaves are green: interaction of light with chloroplasts Chloroplast Light Reflected light Absorbed light Granum Transmitted light

45 Spectrophotometer Spectrophotometer = measures a pigment s ability to absorb various wavelengths This machine sends light through pigments and measures the fracjon of light transmized at each wavelength TransmiZed light is light that is not absorbed 45

46 TECHNIQUE White light 1 Refracting prism Determining an absorption spectrum Chlorophyll solution 2 3 Photoelectric tube 4 Galvanometer Slit moves to pass light of selected wavelength Green light The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light. Blue light The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue light.

47 AbsorpJon Spectrum Absorption spectrum = a graph plotting a pigment s light absorption vs. wavelength Spectrum of chlorophyll a shows that violet-blue and red light work best for photosynthesis An action spectrum profiles the relative effectiveness of different wavelengths of radiation in driving a process such as photosynthesis 47

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49 RESULTS Absorption of light by chloroplast pigments Chlorophyll a Chlorophyll b Carotenoids Absorption spectra Wavelength of light (nm) Action spectrum Rate of photosynthesis (measured by O 2 release) Aerobic bacteria Filament of alga Engelmann s experiment

50 Chlorophyll a is the main photosynthedc pigment It absorbs the light energy Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll 50

51 Chlorophyll CH 3 in chlorophyll a CHO in chlorophyll b Porphyrin ring: light-absorbing head of molecule; note magnesium atom at center Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown

52 Chlorophyll Energy from photons may be absorbed by electrons When a pigment absorbs light, it goes from a group state to an excited state, which is unstable When excited e - s return to the ground state, photons are given off, an auerglow called fluorescence If illuminated, an isolated solujon of chlorophyll will fluoresce, giving off light and heat 52

53 Chlorophyll CH 3 in chlorophyll a CHO in chlorophyll b Porphyrin ring: light-absorbing head of molecule; note magnesium atom at center Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown

54 Excitation of isolated chlorophyll by light e Excited state Energy of electron Photon Chlorophyll molecule Ground state Heat Photon (fluorescence) (a) Excitation of isolated chlorophyll molecule (b) Fluorescence

55 55 CW