Neither chlorophyll absorbs light very well in the green region

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1 Phtsynthesis The Phtsynthesis Equatin 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 In ther wrds, Phtsynthesis uses the energy f sunlight t cnvert water and carbn dixide int xygen and high-energy sugars In the spectrum f energy waves, the visible spectrum is a small sectin in which different clrs have different wavelengths The plant s principal pigment is chlrphyll Tw Kinds f Chlrphyll Chlrphyll a absrbs light best in the red regin Chlrphyll b absrbs light best in the blue regin Neither chlrphyll absrbs light very well in the green regin Plants als cntain red and range pigments that absrb light in ther regins f the spectrum Lk int the Light Because light is a frm f energy, any cmpund that absrbs light als absrbs energy When chlrphyll absrbs the light energy, it transfers it t electrns within the chlrphyll mlecule, raising their energy These high energy electrns are what make phtsynthesis wrk Chlrplasts, Up Clse and Persnal Chlrplasts cntain disks f phtsynthetic membranes called thylakids Thylakids are arranged in stacks, knwn as grana (singular, granum) Thylakids cntain clusters f pigments and prteins knwn as phtsystems that are able t capture light energy The tw stages f Phtsynthesis Light-Dependent Rxns Use energy frm light t cnvert ADP t ATP and NADP + t NADPH Light-Independent Rxns r Calvin Cycle

2 Uses ATP and NADPH t prduce high-energy sugars Light-Dependent Rxns Light energy is absrbed by pigments in Phtsystem II and the electrns in the pigments becme high-energy electrns These electrns are passed n t an electrn transprt chain (ETC) in the thylakid membrane High energy electrns mve thrugh the ETC frm phtsystem II (PSII) t phtsystem I (PSI) PSI uses energy frm the sun t reenergize the electrns These electrns mve dwn the ETC and NADP + then picks them up fr later use Des phtsystem II ever run ut f electrns? Water mlecules are brken int 2 electrns, 2 prtns (H + ), and xygen These tw electrns replace the electrns that went t the ETC The xygen is released as O 2 The 2 H + ins are released inside the thylakid membrane The cncentratin f H + inside the thylakid is great enugh t drive the prductin f ATP via ATP synthase The Calvin Cycle The NADPH and ATP frmed by the light-dependent reactins are nt stable enugh t stre energy During the Calvin cycle plants use energy that ATP and NADPH cntain t build high-energy C6 sugars NADPH prvides the energy and the H s What ges in must cme ut 6 Carbns enter the Calvin Cycle (as 6 CO 2 ) 6 Carbns leave the Calvin Cycle (as a 6 Carbn sugar) Energy Balance It takes the energy f 12 ATPs and 12 NADPHs t turn 6 CO 2 int 1 C6 sugar

3 The cycle uses mre 6 ATPs when regenerating the starting material Net LOSS f ATP = 18 Where d they g? Respiratin ENERGY FOR CELLS TWO TYPES OF CHEMICAL REACTIONS Endergnic energy is absrbed. Energy f the prducts is greater than the energy f the reactants. Uphill Exergnic Energy is released. Energy f the prducts is less than the energy f the reactants. Dwnhill Still requires activatin energy ENERGY FOR CELLS All living things get energy frm the sun either directly r indirectly. Plants use the sun s energy directly t make fd Sunlight energy must be changed t energy trapped within the bnds f fd Animals use the sun s energy indirectly thrugh the fd made by plants ATP Adensine TriPhsphate It is the majr energy currency f the cell It is made f a nitrgen base (adenine), a sugar (ribse), and three phsphate grups When the third phsphate grup f ATP is remved by hydrlysis, a large amunt f energy is released. Hydrlysis = when a mlecule is brken dwn by adding water ATP ADP + P i ADP is Adensine DiPhsphate.

4 P i is inrganic phsphate Yur bdy can use the energy released frm breaking the 3 rd phsphate bnd f ATP t d wrk. The amunt f energy given ff frm ATP is the perfect amunt fr cells. Yur bdy can als make ATP frm ADP. CELLULAR RESPIRATION Cellular respiratin is the prcess by which the chemical energy f "fd" mlecules is partially transferred t ATP. Breaking dwn fd fr energy. Lipids, prteins, fats, and carbhydrates can be brken dwn fr energy. Our fcus is n glucse. Tw types f respiratin: Aerbic uses xygen Occurs in the mitchndria Anaerbic uses n xygen (als called fermentatin) Occurs in the cytplasm AEROBIC RESPIRATON The energy in the chemical bnds f glucse is partially transferred t ADP t make ATP. 60% f the energy frm glucse is lst as heat. Glucse is brken dwn. Oxygen is needed t cmpletely break dwn glucse. Carbn dixide is released. Glyclysis The first set f reactins in cellular respiratin is Glyclysis Glyclysis is the prcess in which 1 mlecule f glucse (C6) is brken in half, prducing tw mlecules f pyruvic acid (C3) Glyclysis ccurs in the cytplasm

5 ATP Prductin Glyclysis is an energy-releasing prcess, but the cell needs t invest a little energy t get things started 2 ATPs are needed t get glyclysis started, but at the end 4 ATPs are prduced Since we already invested 2 ATP, we have a net gain f 2 ATP NADH Prductin One f the reactins in glyclysis remves high energy electrns frm each 3 carbn mlecule and passes them t an electrn carrier, NAD + NAD + hld n t the electrns until it can pass them t ther mlecules within the mitchndria The Krebs Cycle After glyclysis, abut 90% f the chemical energy f glucse is still trapped in the high-energy electrns f pyruvic acid During the Krebs cycle, pyruvic acid is brken dwn and carbn dixide is released The Krebs cycle ccurs in the mitchndria The Krebs cycle begins when pyruvic acid enters the mitchndrin and is changed t anther mlecule Pyruvic acid jins with a cmpund called Cenzyme-A t make acetyl-ca CO 2 is given ff Acetyl-CA jins with a 4 carbn mlecule t make citric acid (6C) Citric acid enters the Krebs cycle and is eventually brken dwn int a 4 carbn mlecule The prducts f the Krebs cycle include CO 2, ATP, NADH, and FADH 2 (a different electrn carrier) The Krebs cycle is where the energy pay-ff is the largest What Happens t all f these Prducts??? NADH and FADH 2 g t the Electrn Transprt Chain t make ATPs The CO 2 released is the carbn dixide yu breathe ut when yu exhale The ATPs can be used fr cellular activity

6 Electrn Transprt The Electrn Transprt Chain (ETC) is a series f prteins in the inner mitchndrial membrane that pass alng the high energy electrns f NADH and FADH 2 These high-energy electrns are used by the ETC t cnvert ADP t ATP Hw ATPs are Made NADH and FADH 2 bring their high energy electrns t specific prteins within the inner mitchndrial membrane These special prteins are arranged in a line and make up the Electrn Transprt Chain The electrns then jump frm ne prtein t the next and lse a bit f energy in each jump NADH electrns have mre energy than FADH 2 electrns, thus they are drpped ff higher in the ETC Every time the electrns make a jump they carry with them a prtn (H + ) and drp them ff in the space between membranes What s the Pint? At the end f every ETC there is a special enzyme called ATP synthase The H + diffuse thrugh the ATP synthase creating enugh energy t add a phsphate t ADP t make ATP What abut ur electrns? At the end f the ETC the electrns need a place t g Oxygen is the final electrn acceptr which accepts tw electrns and 2 H + per xygen atm The pint? N xygen, n Krebs cycle This xygen is the xygen that we breathe in every time we take a breath This means that fr each mlecule f glucse yu can make a maximum f 38 ATPs ANAEROBIC RESPIRATION (FERMENTATION) In many cells, if xygen is nt present, glucse is brken dwn in a prcess called fermentatin. Less ATP is made in anaerbic respiratin than in aerbic respiratin. In animals, lactic acid is made.

7 In yeast, alchl (ethanl) and carbn dixide are made. Lactic Acid Fermentatin In animals, if enugh xygen is nt present, respiratin stps at Glyclysis Pyruvic acid is cnverted t Lactic acid s that NAD + can be regenerated ALCOHOLIC FERMENTATION In yeast, if xygen is nt present, respiratin als stps at Glyclysis Pyruvic acid is cnverted t an Alchl (ethanl) s that NAD + can be regenerated Aerbic vs. Anaerbic Respiratin Aerbic respiratin gives us 38 ATPs (maximum) frm each mlecule f glucse Anaerbic respiratin gives us 2 ATPs frm each mlecule f glucse