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Presentation on theme: "CHAPTER 8: PHOTOSYNTHESIS"— 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 Autotrophs and Heterotrophs
Example: plants use sunlight to make food Heterotrophs= 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 B. Chemical Energy and ATP
Forms of energy: light, heat, electricity, and _____ (Adenosine Triphosphate)= Section 8-1 Chemical energy (stored in bonds) ATP The basic energy source (chemical energy) of all cells Adenine Ribose 3 Phosphate groups

5 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 2nd and 3rd phosphate group

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

7 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
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 CO2 + 6H2O + SUNLIGHT → C6H12O6 (SUGAR) + 6O2

9 6 CO2 + 6H2O + SUNLIGHT → C6H12O6 (SUGAR) + 6O2

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

11 Light Energy Chloroplast (Chlorophyll) Sugars + O2 CO2 + H2O
Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast (Chlorophyll) Sugars + O2 CO2 + H2O

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 ______________ 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 http://www. teachersdomain
5 years 2.3 kg. (5 lb.) plant 90.8 kg (200 lbs). soil 76.8 kg (169 lbs. 3 oz.)  Soil 57 g less

15 ___________ 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 ________________Experiment (1779)
Put aquatic plants in light... Put aquatic plants in dark... He determined: _______________ (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) water Carbon dioxide light chlorophyll light A mixture of different wavelengths Visible Spectrum pigments Chlorophyll a Chlorophyll b

20 Chlorophyll absorbs light in the __________ and ___ wavelengths
Blue-violet Figure 8-5 Chlorophyll Light Absorption red Section 8-2 Absorption of Light by Chlorophyll a and Chlorophyll b RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET Chlorophyll b Chlorophyll a Gamma rays X-rays UV Infrared Micro- waves Radio waves Visible light Wavelength (nm) V B G Y O R

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
LEAF CROSS SECTION MESOPHYLL CELL LEAF Mesophyll CHLOROPLAST Intermembrane space Outer membrane Granum Inner membrane Grana Stroma Thylakoid compartment Stroma Figure 7.2 Thylakoid

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

24 Photosynthesis is a two part process: -aka: 2.
Light-dependent reactions (located in thylakoid membranes) Light Reaction Light-independent reactions (located in stroma) Dark reaction Figure 8-7 Photosynthesis: An Overview Calvin Cycle Section 8-3 Carbon fixation H20 Light O2 Sugars CO2 Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH

25 LIGHT REACTIONS (in grana) CALVIN CYCLE (in stroma)
An overview of photosynthesis H2O CO2 Chloroplast Light NADP+ ADP + P LIGHT REACTIONS (in grana) CALVIN CYCLE (in stroma) ATP Electrons NADPH O2 Sugar Figure 7.5

26 2e- 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+ NADPH Covalent bonds of NADPH are broken to release the high energy electrons.

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

28 Overview of the Light Reaction
Electron Transport Chain Electron Transport Chain e~ e~ e~ ADP ATP e~ NADP NADPH light light PSII PSI 2H2O O2 + 4H+ 4e~

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

·    Photosystem I and II: ·    Electron carriers: ·    Water: ATP Synthase: Clusters of chlorophyll pigment ADP and NADP+ Donates electrons Enzyme (protein) that makes ATP

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

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

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

34 A. Photosystem II (PSII). Absorbs light to. 2H2O. o e- =. o O2 =
A. Photosystem II (PSII) * Absorbs light to   2H2O   o  e- = o  O2 = o  H+= B. Electron Transport Chain * The light energy * The electrons get passed split (break up) water molecules → 4H e- + O2 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
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. O2 ATP & NADPH help build glucose

37 Stroma with or without light.
Section 8-3 D. The Calvin Cycle (dark reaction; light independent) * Occurs in the Figure 8-11 Calvin Cycle Stroma with or without light. CO2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced Sugars and other compounds

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

A. CO2 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 CO2 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

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 Concept Map Photosynthesis Light- dependent reactions Calvin cycle
Section 8-3 Photosynthesis includes Light- dependent reactions Calvin cycle takes place in uses use take place in Thylakoid membranes Stroma NADPH ATP Energy from sunlight to produce of to produce ATP NADPH O2 Chloroplasts High-energy sugars

42 California State Standards
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. Why do animals have to eat to gain energy and plants do not? Why do organisms need energy?

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

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

46 United Streaming video: Photosynthesis (13 min)


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