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PHOTOSYNTHESIS AND CELLULAR RESPIRATION. Chap 5 Section 1. ENERGY AND LIVING THINGS. Metabolism involves either using energy to build molecules or breaking down molecules in which energy is stored - PowerPoint PPT Presentation



    Chap 5

    Section 1

  • ENERGY AND LIVING THINGSMetabolism involves either using energy to build molecules or breaking down molecules in which energy is storedPHOTOSYNTHESIS - the process by which light energy is converted to chemical energy of carbohydrates - sugar and starches

  • AUTOTROPHS organisms that use energy from sunlight or from chemical bonds inorganic substances to make organic compounds (food)

  • Some prokaryotes use chemosynthesis to produce organic compounds

  • HETEROTROPHS organisms that must get energy from food instead of directly from sunlight or inorganic substances

  • CELLULAR RESPIRATION a metabolic process similar to burning fuel, but it converts food energy to ATPATP provides cells with the energy needed to carry out the activities of life

  • Chemical energy stored in food is released graduallyThe product of one chemical reaction becomes a reactant in the next reactionSome of the energy is released as heat, but the remaining energy is stored as ATP portable form of energyAdenosine triphosphate

  • Flow of EnergyEnergy flows from sunlight or inorganic substances to autotrophs, such as grasses, and then to heterotrophs, such as rabbits and foxes

  • Energy Storage in OrganismsPlants store energy in the form of starchAnimals store energy in the form of glycogen

  • Complete sentencesP.96 section review 1-6P. 112 5a,6,12

  • PHOTOSYNTHESISsection 2Using the Energy in Sunlight

  • Requirements for PhotosynthesisSunlight nearly all organisms on Earth depend on sun for energyPigments colored substance that absorb or reflect light

  • Energy-Storing Compounds stored in the bonds of compoundsMost important compound one used by every living cell ATPAdenosine triphosphateInorganic substances Water and Carbon Dioxide

  • White Light perceived as colorlessActually a mixture of different wavelengths of lightVisible spectrum wavelengths visible to our eyesInfrared and ultraviolet not visible to our eyes

  • About 1 % of the energy in the sunlight is converted to chemical energyThree stages of PhotosynthesisStage 1: Energy is captured from sunlight.Stage 2: Conversion of Light EnergyStage 3: Storage of Energy

  • Stage 1Absorption of Light EnergyFirst & second stages are sometimes called light reactionsLight is a form of radiation energy in the form of wavesPigments absorb only certain wavelengths and reflect all the othersChlorophyll absorbs mostly blue & red lights

  • Plants contain two types of chlorophyll, a and b, a being the most importantCarotenoids pigments that produce yellow & orange colors absorb wavelengths of light different from chlorophyllMost of the pigments reflect the color green, making the leaves appear green

  • Production of OxygenThylakoids-located in the chloroplasts & contain the pigments necessary for photosynthesisLight energy is transferred to electrons causing them to be excited

  • Electrons jump to other molecules where they are used to power the second stageReplacement electrons come from water moleculesWater molecules are split by enzymes, leaving H+ ions, and O atoms, forming Oxygen gas,

  • Stage Two: Conversion of Light EnergyElectron Transport Chains (2)- series of molecules through which excited electrons are passed along a thylakoid membraneFirst, provides the energy needed to change ADP to ATP needed by dark reaction

  • A second electron transport chain provides energy used to make NADPH- which is needed by the dark reactionNADPH electron carrier that provides the high-energy electrons needed to make carbon-hydrogen bonds in the third stageExcited electrons combine with hydrogen ions & NADP+ to form NADPH

  • Animated Light Reaction

  • Photosynthesis Problem

  • Dark Reaction(Light Independent Reaction)Dark reactions generally take place in sunlight; light does not play a role in the dark reactionsThe simple inorganic molecule carbon dioxide is used to make a complex organic moleculeMelvin Calvin, American, worked out cycle

  • Stage Three: Storage of EnergyCARBON DIOXIDE FIXATION transfer of carbon dioxide to organic compoundsConsidered light-independent dark reactionsMost common method is the Calvin cycleCalvin cycle- a series of enzyme-assisted chemical reactions that produces a 3-C sugar

  • The reactions are cyclic they recycle the five-carbon compound needed to begin the cycle againThe energy used in the Calvin cycle is supplied by ATP and NADPH made during the second stage of photosynthesis

  • Calvin Cycle Animated

  • Light and Dark Reactions

  • Factors that Affect PhotosynthesisLight photosynthesis increases as light intensity increases until all the pigments are being used limited by Calvin reaction which is the slowest stepCarbon dioxide concentration once a certain concentration is reached photosynthesis is limitedTemperature- certain range is more efficient

  • Water the availability of water and the amount of rainfallNutrients how much organic matter that soil contains

  • P. 103Section 2 review 1-6P. 112 1,2, 5c,8,9, 11Standardized Test Prep 1-3

  • Cellular RespirationFood contains usable energy in the form of protein, fat, & carbs (considered organic)Energy has to be transferred to ATP, which is done through cellular respirationAEROBIC respiration- metabolic processes that require oxygen, more efficient in making ATPANAEROBIC-metabolic processes that do not require O2

  • Stages of Cellular RespirationStage I: Breakdown of GlucoseStage II: Production of ATP

  • Stage I: Breakdown of GlucoseGlycolysis: takes place in the cytoplasm- an enzyme-assisted anaerobic process that breaks down one 6-C molecule of glucose to 2 3-C pyruvic ions4 Steps in the series on page 105 you can copy them from the book

  • Glycolysis uses two ATP but produces four ATP

  • Stage 2: Production of ATPKrebs Cycle enzyme-assisted reactions named for Hans Krebs, 19375 steps on p. 106 & 107Much of the energy that was stored in glucose & pyruvate is now stored in NADH and FADH2

  • Krebs Cycle

  • Electron Transport ChainThe electron transport chain pumps hydrogen ions, H+, out of the inner compartment.At the end of the chain, electrons & hydrogen ions combine with oxygen, forming water.ATP is produced as hydrogen ions diffuse into the inner compartment through a channel protein.

  • Respiration in the Absence of OxygenElectron transport chain does not function if oxygen is not available as final electron acceptor.Electrons in NADH are transferred to pyruvate; enables the recycling of NAD+ which is needed to make ATPFermentation- recycling of NAD+ using an organic hydrogen acceptor

  • Lactic Acid FermentationPyruvate is converted to lactateLactate is the ion of lactic acidVigorous exercise muscles must operate without enough O2 ATP produces only while glucose supply lastsBlood removes excess lactate, but if not quickly-can cause muscle soreness

  • Alcoholic FermentationTwo step processPyruvate is converted to 2-C compound, releasing CO2 Electrons are transferred from NADH to the two-C compound, producing ethanolYeast, a fungus, uses alcoholic fermentation. Yeast is used in bread industry and alcoholic beveragesEthanol (12%) kills yeast

  • Production of ATPTotal of ATP produced from glucose depends on the absence or presence of O22 ATP molecules are made during the Krebs cycle34 ATP are produced by the electron transport chain

  • Types of chemical reactionsAn exothermic reaction is a chemical reaction that releases energy in the form of heat..

  • An endothermic reaction is any chemical reaction that absorbs heat from its environment. These examples could be written as chemical reactions, but are more generally considered to be endothermic or heat-absorbing processes: melting ice cubes melting solid salts evaporating liquid water

  • converting frost to water vapor (melting, boiling, and evaporation in general are endothermic processes) splitting a gas molecule cooking an egg

  • Homework

    Page 110 - section review 1-6Page 112 3,4, 5b, 5d,7,10,13,14,19Test Part 2 over section 3 Monday 8th10 true false 14 multiple choice and discussion