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Photosynthesis PS Learning Targets 1-8. LT’s 1-3:Energy and Old Dead Dudes LT’s 4 & 5:Light and Structures of PS LT’s 6-8:Reactions and Factors of PS.

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Presentation on theme: "Photosynthesis PS Learning Targets 1-8. LT’s 1-3:Energy and Old Dead Dudes LT’s 4 & 5:Light and Structures of PS LT’s 6-8:Reactions and Factors of PS."— Presentation transcript:

1 Photosynthesis PS Learning Targets 1-8

2 LT’s 1-3:Energy and Old Dead Dudes LT’s 4 & 5:Light and Structures of PS LT’s 6-8:Reactions and Factors of PS

3 All living things need energy to live! – Heterotrophs – Heterotrophs-get their food by eating other organisms and turning them into energy (Ex: herbivores, carnivore, decomposers, etc) – Autotrophsconverting light or chemical energy into sugar, and then converting that into energy – Autotrophs-get their energy by converting light or chemical energy into sugar, and then converting that into energy (Ex: plants, bacteria, and some protists) LT 1

4 The cell will store energy in molecules like sugars and ATP The cell will store energy in molecules like sugars and ATP small stores of ATP – Most cells have small stores of ATP that only last a few seconds, but cannot store energy there long-term. carbohydrates/ – Cells will store it long term in carbohydrates/ sugars sugars – Sugar energy > ATP energy 90x greater

5 ENERGY What are the uses for ATP in biochemical reactions? Active Transport Energy to move cell organelles Making proteins or nucleic acids PHOTOSYNTHESIS!!! PHOTOSYNTHESIS!!! PHOTOSYNTHESIS!!!

6 LT 2

7 CO 2 H 2 OC 6 H 12 O 6 O 2 6 CO 2 + 6 H 2 O light C 6 H 12 O 6 + 6 O 2 From the air From the roots From the sun Made in the dark rxn Made in the light rxn Will be made into ATP later in Cellular Respiration LT 3

8 CO 2 H 2 Olight C 6 H 12 O 6 O 2 6 CO 2 + 6 H 2 O light C 6 H 12 O 6 + 6 O 2 SUNLIGHT Photosynthesis starts with SUNLIGHT! ROYGBIV The light that comes from the sun is WHITE LIGHT or ROYGBIV (R O Y G B I V) The red end is lower The red end is lower energy and longer wavelength The violet end has The violet end has higher energy and smaller wavelength LT 4

9 ? If plants use visible light, are all colors/wavelengths/energies equally valuable to PS? Let’s see… Read the results of the experiment from Thomas Engelmann in 1803

10 GREEN Most plants are GREEN. This means that ROY BIV is absorbed ROY BIV is absorbed and G is reflected. these are the colors of light that power PS This means that if ROY and BIV are absorbed these are the colors of light that power PS Pigment – any substance that absorbs light Chlorophyll a – the main pigment in plants that absorbs the sun’s light to power PS

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12 Light and PigmentsLight and Pigments ACCESSORY PIGMENTS There are also other pigments, beside chlorophyll a, called ACCESSORY PIGMENTS chlorophyll b and carotenoids optimal portion of ROYGBIV for absorption Each pigment has its optimal portion of ROYGBIV for absorption and to fuel PS accessory pigments help chlorophyll a by expanding the portion of ROYGBIV it can use! Chlorophyll a is the main pigment for PS, while the accessory pigments help chlorophyll a by expanding the portion of ROYGBIV it can use!

13 Chlorophyll a best absorption occurs around 425nm AND 660nm Chlorophyll b best absorption occurs around 475nm AND 640nm Carotenoids best absorption occurs around 450nm AND 490nm Therefore, the accessory pigments expand the absorption from about 425nm (V) to 425-490nm (V-B) AND from 660nm (R) to 640-660nm (O-R). More light absorbed = More PSing!!

14 Why do leaves change color in the fall? 1.What are the three kinds of pigments? 2.What two factors cause the color to change? 3.What three factors will give good fall color, especially reds?

15 Remember…leaves get their colors from their pigments Remember…leaves get their colors from their pigments PIGMENTCOLORWHEN ACTIVE ChlorophyllgreenPresent all year Carotenoidsyellow, oranges, and browns Present all year but covered by chlorophyll in summer Anthocyaninsred Only produced in autumn under certain conditions

16 Why do leaves change color in the fall? So how do they know to change color?? 1.Fewer hours of sunlight/days are shorter Trees produce less and less chlorophyll Trees produce less and less chlorophyll Now carotenoids (already in leaf) can show through Now carotenoids (already in leaf) can show through 2.Drop in temperature

17 Why do leaves change color in the fall? But what about the anthocyanins? This is dependent upon… This is dependent upon… Temperature and cloud cover Temperature and cloud cover Warm days and cool nights = good reds Warm days and cool nights = good reds Help plants get all the remaining sugar out of the leaves before they fall off Help plants get all the remaining sugar out of the leaves before they fall off So for good fall leaf color… A warm, wet summer A warm, wet summer A summer that is not too hot or dry A summer that is not too hot or dry A fall with many warm days and cool nights A fall with many warm days and cool nights

18 Cell Membrane A phospholipid bilayer embedded with proteins A phospholipid bilayer embedded with proteins Selectively permeable Selectively permeable Maintains homeostasis for the cell via Maintains homeostasis for the cell via – PASSIVE (diffusion, osmosis, or facilitated diffusion) – ACTIVE TRANSPORT (active transport, endocytosis or exocytosis) NowThe Leaf and Chloroplasts Now…The Leaf and Chloroplasts The structures plants use for PS The structures plants use for PS LT 5

19 The Leaf Cuticle- the waxy outer covering of a leaf that prevents water loss Palisdade Layer-layer of long cells where chloroplasts are found and where most of PS occurs Spongy Mesophyll-random collection of cells with large spaces in between them. Some PS occurs here, but mostly this is where the gases taken in & given off by PS are exchanged between palisade layer and stoma

20 The Leaf (cont.) Stoma- openings on the underside of leaves that allow for gas exchange between the leaf and atmosphere. Guard Cells-the cells on either side of the stoma that open/close them to let gases in or out OR to keep gases in

21 The Chloroplast Organelle responsible for PHOTOSYNTHESIS! Organelle responsible for PHOTOSYNTHESIS! Disc-like in shape Disc-like in shape Green due to the presence of the pigment Chlorophyll a Green due to the presence of the pigment Chlorophyll a Found mostly within the palisade layer, but some are in the mesophyll too. Found mostly within the palisade layer, but some are in the mesophyll too. Internal structures include Internal structures include – Thylakoids – StRoma – Granum (sing.) or Grana (pl.) – Lumen Let’s see this Let’s see this

22 The Chloroplast (cont.) 1 of 2 membranes that surround the organelle Fluid between the thylakoids where the dark rxn occurs Disc where the pigments of PS are Where the light rxn occurs Disc where the pigments of PS are. Where the light rxn occurs

23 ? So what about the rest of the PS equation; like CO 2, Water, Glucose and O 2 ? CO 2 H 2 O light C 6 H 12 O 6 O 2 6 CO 2 + 6 H 2 O light C 6 H 12 O 6 + 6 O 2 PS occurs in 2 parts 1.Light Dependent (or Light Reaction) This part of the rxn requires LIGHT, H 2 O, and gives off O 2 This part of the rxn requires LIGHT, H 2 O, and gives off O 2 2.Light Independent (or Dark Reaction) This part of the rxn requires CO 2 and produces the sugar or glucose This part of the rxn requires CO 2 and produces the sugar or glucose LT’s 6 & 7

24 Reactants Products

25 The Light Reaction “I’m So Excited!” e- electron carriers receive chlorophyll’s electronsthe excited e-’s and pass get very excited from the them along to other sun’s energy molecules. These e-’s carriers molecules are chlorophyll’s electronsthe excited e-’s and pass get very excited from the them along to other sun’s energy molecules. These e-’s carriers molecules are called the ELECTRON TRANSPORT CHAIN ELECTRON TRANSPORT CHAIN LT 6

26 The Light Reaction Examples of a Carrier Molecule: NADP + 2e - ’s from chlorophyll 1H + from water Takes 2e - ’s from chlorophyll and 1H + from water NADPH NADP + + 2e - + 1H + NADPH Takes energy with it to other cell rxns UPS truck, picking up “packages” and dropping them off Think of it like a UPS truck, picking up “packages” and dropping them offATP

27 The Light Reaction: Key Concepts thylakoid membrane Occurs in the thylakoid membrane of the chloroplast Photosystem IIPhotosystem I Includes Photosystem II and Photosystem I LightH 2 O to start Needs Light and H 2 O to start O 2, NADPH and ATP Produces O 2, NADPH and ATP Waste!

28 The Light Reaction: Photosystem II PS II - In the Thylakoid Membrane (TM) 1. e- absorb sun’s energy and get highly energized 1. e- absorb sun’s energy and get highly energized 2. The proteins in the TM split a water (hydrolysis) to make 2. The proteins in the TM split a water (hydrolysis) to make H + ’s, e - ’s, and O 2 H + ’s, e - ’s, and O 2 3. e-’s go to ETC (a series of protein carriers) 3. e-’s go to ETC (a series of protein carriers) 4. Energy from the e - ’s pumps H + ’s into the TM, changing the [H + ] ions (low to high-active transport) 4. Energy from the e - ’s pumps H + ’s into the TM, changing the [H + ] ions (low to high-active transport)

29 The Light Reaction: Photosystem I PS I - In the Thylakoid Membrane (TM) 5. Light is energized again 5. Light is energized again adds them to NADP + to make NADPH 6. e - ’s move to the final e - acceptor which adds them to NADP + to make NADPH 7. High [H + ] (left over from hydrolysis) diffuse through the enzyme protein ATP synthase to make ATP form ADP 7. High [H + ] (left over from hydrolysis) diffuse through the enzyme protein ATP synthase to make ATP form ADP (H + give energy to add a phosphate to ADP) Let’s See This

30 The Light Reaction: The Thylakoid Membrane

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32 A Little Quiz: 1.Put a #1 where there is a higher concentration of H + 2.Draw a squiggly line between PSII and PSI 3.Put a #2 on the thylakoid membrane 4.Put a #3 in the stroma 5.Put a #4 where the e-’s are first energized 6.Put a #5 where the e-’s are re-energized 7.Put a #6 where hydrolysis occurs 8.Put a #7 where active transport is occurring.

33 The Dark Reaction: Key Concepts The second part of PS is called the Dark Reaction,the Calvin Cycle, or the Light Independent Cycle The second part of PS is called the Dark Reaction,the Calvin Cycle, or the Light Independent Cycle It is called the Dark Rxn because this part can take place without light (that is not to say it must be dark, It is called the Dark Rxn because this part can take place without light (that is not to say it must be dark, but if it were, but if it were, this part could this part could still proceed) still proceed) LT 7

34 The Dark Reaction: Key Concepts The two products from the Light Reaction, NADPH and ATP go to the Dark Reaction The two products from the Light Reaction, NADPH and ATP go to the Dark Reaction NADPH and ATP have lots of energy in their bonds but they can only hold it for a few minutes NADPH and ATP have lots of energy in their bonds but they can only hold it for a few minutes If the cell wants to hold the energy long-term, they will have to build high energy molecules that can hold it…like GLUCOSE (savings account!) If the cell wants to hold the energy long-term, they will have to build high energy molecules that can hold it…like GLUCOSE (savings account!) This process takes place in the stRoma (outside of chloroplast) This process takes place in the stRoma (outside of chloroplast)

35 The Dark Reaction 6- ATP 6- NADPH 3 -CO 2 3-RuBP’s 5 C’s 3-5C RuBP’s 3-6C Compound- Unstable! 6-3C PGA’s 6-3C PGAL’s 5 stay in cycle 1 exits and will become GLUCOSE From Light Rxn Calvin Cycle Video Calvin Cycle Video 3- ATP

36 Limiting Factors to PS There are factors that limit the amount of PS 1.H 2 O 1.H 2 O –slow or decrease PS 2.Temperature – Recall that enzymes have particular optimal temperatures – Functions best between 0-35°C – Temperatures above or below these temps slow PS – Very low temps STOP PS 3.Light Intensity- increase intensity = increase PS 4.Color of Light – RO and BV preferred LT 8

37 Two rxns: Light and Dark Two rxns: Light and Dark Reactants: H 2 O, CO 2, and Light Reactants: H 2 O, CO 2, and Light Products: O 2 and Glucose Products: O 2 and Glucose Two Locations: Two Locations: – Light –Thylakoid Membrane – Dark- StRoma LT’s 1-8

38 1. 2. 8. 3. 4. 5. 6. 7. 9. 10. 11. 12. 13. Word Bank Photosynthesis ATP (2) Thylakoid Stroma Light Energy from the sun High energy sugars NADPH (2) Oxygen Light-depentdent reaction Calvin Cycle Chloroplast

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