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CHAPTER 8: PHOTOSYNTHESIS. 8-1 Energy of Life  Energy=  Living organisms depend on energy.  Living things get energy from _______.  The ultimate source.

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Presentation on theme: "CHAPTER 8: PHOTOSYNTHESIS. 8-1 Energy of Life  Energy=  Living organisms depend on energy.  Living things get energy from _______.  The ultimate source."— Presentation transcript:


2 8-1 Energy of Life  Energy=  Living organisms depend on energy.  Living things get energy from _______.  The ultimate source of energy is the _____. The ability to do work food sun

3 A.Autotrophs and Heterotrophs  Autotrophs= o Example: plants use sunlight to make food  Heterotrophs= o Example: ___________- eat plants ___________- eat animals that have stored energy from plants they eat ___________- eat decomposing organisms Organisms that make their own food Organisms that need to consume food for energy herbivores carnivores detritovores

4 AdenineRibose3 Phosphate groups Section 8-1 ATP B. Chemical Energy and ATP Forms of energy: light, heat, electricity, and _____ (Adenosine Triphosphate)= Chemical energy (stored in bonds) ATP The basic energy source (chemical energy) of all cells

5 1.Storing Energy ADP (Adenosine Diphospate) contains ____ phosphates instead of 3. If a cell has extra energy, 2. Releasing Energy To release energy stored in ATP, 2 Small amounts can be stored by adding a phosphate group to ADP molecules to produce ATP. The cell can break the high energy bond between the 2 nd and 3 rd phosphate group

6 ADPATP Energy Adenosine diphosphate (ADP) + PhosphateAdenosine triphosphate (ATP) Partially charged battery Fully charged battery Section 8-1 Figure 8-3 Comparison of ADP and ATP to a Battery

7 C.Using Biochemical Energy  How ATP is used in the cell - - aids in -  Cells contain a small amount of ATP. Only enough to provide a few seconds of activity.  ATP is great at ________________ but not good at  Glucose stores ___ times more energy than ATP.  The energy stored in Glucose can be used to Carry out active transport moving organelles throughout the cell Protein synthesis Producing light (ex. fireflys) transferring energy Storing large amounts of energy 90 regenerate ATP when the cell needs it.

8 8-2 Photosynthesis: An Overview  Photosynthesis=  Plants convert ______________ into ______________ through a series of oxidation/reduction reactions.  Process where plants use energy of sunlight to convert water and carbon dioxide into high-energy Carbohydrates-sugars-starches- and oxygen, a waste product. Sunlight energy Chemical energy 6 CO 2 + 6H 2 O + SUNLIGHT → C 6 H 12 O 6 (SUGAR) + 6O 2

9 sunlight O2O2 CO 2 H2OH2O C 6 H 12 O 6

10 Reduction: Gain electrons Oxidation: Lose electrons REDOX REACTIONS LEO: Lose Electrons Oxidation goes GER: Gain Electrons Reduction

11 Light Energy Chloroplast (Chlorophyll) CO 2 + H 2 O Sugars + O 2 Section 8-2 Photosynthesis: Reactants and Products

12 A. Investigating Photosynthesis  Investigations into photosynthesis began with the following question: “When a tiny seedling grows into a tall tree with a mass of several tons, where does the tree’s increase in mass come from?”

13 1.______________ Experiment (1643)  Put soil in pot and took mass  Took a seedling and took mass  Put seed in soil...watered...waited five years... the seedling became a tree.  He concluded that  He determined the Van Helmont’s the mass came from water “hydrate” in the carbohydrate portion of photosynthesis

14 Von Helmont Willow Tree Experiment 2.3 kg. (5 lb.) plant 90.8 kg (200 lbs). soil 76.8 kg (169 lbs. 3 oz.) Soil 57 g less 5 years

15 2.___________ Experiment (1771)  Put a lit candle in a bell jar-  Placed a mint plant in the jar with the candle-  Concluded  He determined Priestly’s The flame died out. Flame lasted longer plants release a substance needed for candle burning. plants release oxygen

16 Alternate Priestly Experiment Credit: The National Science Teachers Association

17 3.________________Experiment (1779)  Put aquatic plants in light...  Put aquatic plants in dark...  He determined: 4._______________ (1948)  He determines  Known as the Jan Ingenhousz produced oxygen No oxygen Light is needed to produce oxygen Melvin Calvin carbon’s path to make glucose Calvin’s cycle


19 B. Light and Pigments  Photosynthesis requires ______ (soil), ____________ (air), and ____ (sun), and ________ (a molecule in chloroplasts).  Energy from the sun is in the form of _____.  Sunlight= perceived as white light=  The wavelengths you can see are part of the _______________.  Plants capture light with light absorbing molecules called ________.  The main pigment is chlorophyll (2 kinds) 1. 2. waterCarbon dioxide light chlorophyll light A mixture of different wavelengths Visible Spectrum pigments Chlorophyll a Chlorophyll b

20 Absorption of Light by Chlorophyll a and Chlorophyll b VBGYOR Chlorophyll b Chlorophyll a Section 8-2 Figure 8-5 Chlorophyll Light Absorption  Chlorophyll absorbs light in the __________ and ___ wavelengths Gamma rays X-raysUVInfrared Micro- waves Radio waves Visible light Wavelength (nm) Blue-violet red RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET

21  Chlorophyll reflects ______ wavelengths (that’s why plants appear green)  The energy absorbed by chlorophyll is transferred to _________ (in chloroplasts) which makes photosynthesis work. green electrons QUESTION: So why do plants leaves change color in the fall? Colorful leaves signal the changes of autumn. As nights grow longer and cooler, the leaves no longer produce chlorophyll, the pigment that makes leaves green and enables the process of photosynthesis. As the green pigment wanes, other pigments take over, producing the brilliant reds, oranges, and yellows of fall foliage.

22 The location and structure of chloroplasts Figure 7.2 LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum StromaGrana

23 Light Chloroplast Reflected light Absorbed light Transmitted light 8-3 The Reactions of Photosynthesis A. Inside a Chloroplast Site of Photosynthesis= The chloroplasts

24  Photosynthesis is a two part process: 1. -aka: 2. -aka: Chloroplast Light O 2 Sugars CO 2 Light- Dependent Reactions Calvin Cycle NADPH ATP ADP + P NADP + Chloroplast Section 8-3 Figure 8-7 Photosynthesis: An Overview Light-dependent reactions (located in thylakoid membranes) Light Reaction Light-independent reactions (located in stroma) Dark reaction Calvin Cycle Carbon fixation H20H20

25 An overview of photosynthesis Figure 7.5 Light Chloroplast LIGHT REACTIONS (in grana) CALVIN CYCLE (in stroma) Electrons H2OH2O O2O2 CO 2 NADP + ADP + P Sugar ATP NADPH

26 B. Electron Carriers  Sunlight energy is transferred to  The electrons  High energy electrons require ANALOGY: If you wanted to transfer hot coals from one campfire to another, it requires a special carrier like a pan or bucket.  Electron carriers pass electrons from carrier to carrier to carrier;  A Key electron carrier in photosynthesis is NADP +. NADP + + + →→ (electron carrier) (high energy electrons) (hydrogen ions) (energy storing compound)  When energy is needed to do cellular work, the electrons in chlorophyll. gain a lot of energy. a special carrier (molecule/compound). Forming an electron transport chain. 2e- H+H+ NADPH Covalent bonds of NADPH are broken to release the high energy electrons.

27 C.Light-Dependent Reactions (Requires Light) · Located in the ___________________________ · In the light reaction, ___________ is used to produce _____ and _______ thylakoid membrane light energy ATPNADPH

28 PSIIPS I 2H 2 O O 2 + 4H + Electron Transport Chain NADP+ NADPH Electron Transport Chain ligh t ADP ATP e~e~ 4e~ e~ e~e~ e~e~ e~e~ Overview of the Light Reaction

29 Primary electron acceptor Electron transport chain Electron transport Photons PHOTOSYSTEM I PHOTOSYSTEM II Energy for synthesis of by chemiosmosis

30 KEY PLAYERS IN LIGHT REACTION:  Photosystem I and II:  Electron carriers:  Water: ATP Synthase: Clusters of chlorophyll pigment ADP and NADP + Donates electrons Enzyme (protein) that makes ATP

31 Figure 7.7C Primary electron acceptor Photon Reaction center PHOTOSYSTEM Pigment molecules of antenna

32 Hydrogen Ion Movement Photosystem II Inner Thylakoid Space Thylakoid Membrane Stroma ATP synthase Electron Transport Chain Photosystem IATP Formation Chloroplast Light Reaction Process:

33 The production of ATP by chemiosmosis in photosynthesis Figure 7.9 Thylakoid compartment (high H + ) Thylakoid membrane Stroma (low H + ) Light Antenna molecules Light ELECTRON TRANSPORT CHAIN PHOTOSYSTEM IIPHOTOSYSTEM IATP SYNTHASE

34 A. Photosystem II (PSII) * Absorbs light to 2H 2 O o e- = o O 2 = o H+= B. Electron Transport Chain * The light energy * The electrons get passed split (break up) water molecules → 4H + + 4e- + O 2 Donated to chlorophyll Released into air providing oxygen for us Released inside the thylakoid membrane excites electrons increasing their energy level. down an electron transport chain to photosystem I (PSI )

35 C. Photosystem I · Light energy energizes electrons. · NADP+ accepts the electrons and an H+ and are used to make _________. D. Hydrogen Ion Movement · When water splits, · The difference in charges E. ATP Formation · _____ do not cross the membrane directly. It needs the help of a membrane protein. · H+ ions pass through the protein: NADPH H+ ions fill up the inner thylakoid membrane (making it positively charged). As a result, the stroma is negatively charged. Provides the energy to make ATP. Ions ATP synthase is an enzyme that converts ADP to ATP

36 PRODUCTS OF THE LIGHT REACTION: · ____ : Released in the air · ______________: These contain abundant chemical energy but they are unstable. So, they are used to power the dark reaction to _________________ which can store the energy for longer periods of time. O2O2 ATP & NADPH help build glucose

37 ChloropIast CO 2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated Sugars and other compounds 6-Carbon Sugar Produced Section 8-3 D. The Calvin Cycle (dark reaction; light independent) * Occurs in the Figure 8-11 Calvin Cycle Stroma with or without light.

38 Section 9.2 Summary – pages 225-230 (CO2) The Calvin Cycle (CO 2 ) (Unstable intermediate) ATP ADP + (Sugars and other carbohydrates) NADPH NADP + (PGAL) ATP (PGAL) (RuPB)

39 DARK REACTION PROCESS: A. CO 2 enters the system product= B. Energy input The _________________________________ are used to C. 6-Carbon Sugar is produced ___ of the 12 3-C are used to make glucose and other compounds. D. 5-Carbon Molecules Regenerated ___ remaining 3-C are converted into 6 5-C molecules 6 CO 2 combines with 6 5-C compounds 12 3-C compounds ATP & NADPH (from the light reaction) convert the 12 3-C compounds into a higher energy form. 2 10

40 PRODUCTS OF THE CALVIN CYCLE (DARK REACTION): * E. Factors Affecting Photosynthesis * * Plants often have a ______ coating to protect against * * The greater the _____________, the better photosynthesis functions (up to a point). High Energy Sugars Shortage of water can stop/slow down photosynthesis waxy Very low/high temperatures (damages enzymes) can stop/slow down photosynthesis (optimal temp.= 0°– 35° C Light intensity

41 Photosynthesis includes of take place in takes place in uses to produce use Light- dependent reactions Calvin cycle Thylakoid membranes StromaNADPH ATP Energy from sunlight ATPNADPHO2O2 Chloroplasts High-energy sugars Section 8-3 Concept Map

42 California State Standards Cell Biology Cell Biology 1a: usable energy is captured from sunlight by chloroplasts and is stored through the synthesis of sugar from carbon dioxide

43 Warm up 8-1 Draw an ATP molecule and describe why it is considered an energy molecule. Draw an ATP molecule and describe why it is considered an energy molecule. Why do animals have to eat to gain energy and plants do not? Why do animals have to eat to gain energy and plants do not? Why do organisms need energy? Why do organisms need energy?

44 Warm-up 8-2 Describe what the data represents in figure 8-5 pg 207. Describe what the data represents in figure 8-5 pg 207. Why are plants green? Why are plants green? What do plants need to grow? Where are they obtaining these substances? What do plants need to grow? Where are they obtaining these substances?

45 Warm-up 8-3 Diagram the process of photosynthesis in detail. Diagram the process of photosynthesis in detail.

46 United Streaming video: Photosynthesis (13 min)

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