BIOLOGY 101. CHAPTER 10: Photosynthesis: Process that Feeds the Biosphere

Transcription

1 BIOLOGY 101 CHAPTER 10: Phtsynthesis: Prcess that Feeds the Bisphere

2 Phtsynthesis: Prcess that Feeds the Bisphere CONCEPTS: 10.1 Phtsynthesis cnverts light energy t the chemical energy f fd 10.2 The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar Can yu describe r explain these prcesses? Why are these prcesses significant?

3 Phtsynthesis: Prcess that Feeds the Bisphere 10.1 Phtsynthesis cnverts light energy t the chemical energy f fd Phtsynthetic enzymes and ther mlecules are gruped tgether in a bilgical membrane, allwing the necessary series f chemical reactins t be carried ut efficiently The prcess f phtsynthesis likely riginated in a grup f bacteria with inflded regins f the plasma membrane cntaining clusters f such mlecules. In existing phtsynthetic bacteria, inflded phtsynthetic membranes functin similarly t the internal membranes f the chlrplast.

4 What is the name f the thery that explains were mitchndria and chlrplasts came frm? The Endsymbint Thery There is cnsiderable evidence supprting this thery!

5 Phtsynthesis: Prcess that Feeds the Bisphere 10.1 Phtsynthesis cnverts light energy t the chemical energy f fd Phtsynthetic enzymes and ther mlecules are gruped tgether in a bilgical membrane, allwing the necessary series f chemical reactins t be carried ut efficiently The prcess f phtsynthesis likely riginated in a grup f bacteria with inflded regins f the plasma membrane cntaining clusters f such mlecules. In existing phtsynthetic bacteria, inflded phtsynthetic membranes functin similarly t the internal membranes f the chlrplast. The endsymbint thery suggests that riginal chlrplast was a phtsynthetic prkaryte that lived inside a eukarytic cell.

6 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Chlrplasts are the sites f phtsynthesis in plants All green parts f a plant have chlrplasts, but leaves are the majr sites f phtsynthesis fr mst plants. Chlrplasts are fund mainly in cells f mesphyll, the tissue in the interir f the leaf. O 2 exits and CO 2 enters the leaf thrugh micrscpic pres called stmata in the leaf. Veins deliver water frm the rts and carry ff sugar frm mesphyll cells t rts and ther nnphtsynthetic areas f the plant. A typical mesphyll cell has chlrplasts

7 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Chlrplasts are the sites f phtsynthesis in plants Each chlrplast has tw membranes arund a dense fluid called the strma. Suspended within the strma is an internal membrane system f sacs, the thylakids. The interir f the thylakids frms anther cmpartment, the thylakid space. Thylakids may be stacked in clumns called grana

8 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Chlrplasts are the sites f phtsynthesis in plants Chlrphyll, the green pigment in the chlrplasts, is lcated in the thylakid membranes. Chlrphyll plays an imprtant rle in the absrptin f light energy during phtsynthesis. The phtsynthetic membranes f prkarytes arise frm inflded regins f the plasma membranes, als called thylakid membranes

9 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Pwered by light, phtsynthesis prduces rganic cmpunds and O 2 frm CO 2 and H 2 O The equatin describing the prcess f phtsynthesis is 6CO H 2 O + light energy C 6 H 12 O 6 + 6O 2 + 6H 2 O Just as in Cellular respiratin, it is critical t be able t track the path f the electrns and energy Additinally, pay attentin t bth the reactants and the prducts f the reactin

10 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Pwered by light, phtsynthesis prduces rganic cmpunds and O 2 frm CO 2 and H 2 O The equatin describing the prcess f phtsynthesis is 6CO H 2 O + light energy C 6 H 12 O 6 + 6O 2 + 6H 2 O C 6 H 12 O 6 is glucse, althugh the direct prduct f phtsynthesis is actually a three-carbn sugar that can be used t make glucse. Water appears n bth sides f the equatin because 12 mlecules f water are cnsumed and 6 mlecules are newly frmed during phtsynthesis thrugh chemismsis

11 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Pwered by light, phtsynthesis prduces rganic cmpunds and O 2 frm CO 2 and H 2 O We can simplify the equatin by shwing nly the net cnsumptin f water: 6CO 2 + 6H 2 O + light energy C 6 H 12 O 6 + 6O 2 Written this way, the verall chemical change during phtsynthesis is the reverse f cellular respiratin. Bth f these metablic prcesses ccur in plant cells. Hwever, chlrplasts d nt synthesize sugars by simply reversing the steps f respiratin. In its simplest pssible frm, CO 2 + H 2 O + light energy [CH 2 O] + O 2 where [CH 2 O] represents the general frmula fr a carbhydrate.

12 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Phtsynthesis is a redx reactin Bth phtsynthesis and aerbic respiratin invlve redx reactins. During cellular respiratin, energy is released frm sugar when electrns assciated with hydrgen are transprted by carriers t xygen, frming water as a by-prduct. The electrns lse ptential energy as they fall dwn the electrn transprt chain tward electrnegative xygen, and the mitchndrin harnesses that energy t synthesize ATP. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP Phtsynthesis reverses the directin f electrn flw. 6CO 2 + 6H 2 O + light energy C 6 H 12 O 6 + 6O 2

13 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Phtsynthesis is a redx reactin Bth phtsynthesis and aerbic respiratin invlve redx reactins. During cellular respiratin, energy is released frm sugar when electrns assciated with hydrgen are transprted by carriers t xygen, frming water as a by-prduct. The electrns lse ptential energy as they fall dwn the electrn transprt chain tward electrnegative xygen, and the mitchndrin harnesses that energy t synthesize ATP. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP Phtsynthesis reverses the directin f electrn flw. 6CO 2 + 6H 2 O + light energy C 6 H 12 O 6 + 6O 2

14 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 Phtsynthesis is a redx reactin Water is split and electrns are transferred with H+ frm water t CO 2, reducing it t sugar. Because the electrns increase in ptential energy as they mve frm water t sugar, the prcess requires energy. The energy bst is prvided by light. 6CO 2 + 6H 2 O + light energy C 6 H 12 O6 + 6O 2

15 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis Phtsynthesis is tw prcesses, each with multiple steps: light reactins and the Calvin cycle. The light reactins (pht) cnvert slar energy t chemical energy.

16 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis Phtsynthesis is tw prcesses, each with multiple steps: light reactins and the Calvin cycle. The light reactins (pht) cnvert slar energy t chemical energy. The Calvin cycle (synthesis) uses energy frm the light reactins t incrprate CO 2 frm the atmsphere int sugar

17 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis Thus, light energy is initially cnverted t chemical energy in the frm f tw cmpunds: NADPH, a surce f electrns as reducing pwer that can be passed alng t an electrn acceptr, and ATP, the energy currency f cells. High energy electrns used fr phtsynthesis are ging the ppsite directin than thse used fr cellular respiratin This means they need a different taxi r carrier mlecule Cellular respiratin uses NAD + as a carrier Phtsynthesis uses NADP + as a carrier

18 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis The light reactins prduce n sugar; that happens in the secnd stage f phtsynthesis, the Calvin cycle. The Calvin cycle is named fr Melvin Calvin, wh, with his clleagues, wrked ut many f its steps in the 1940s.

19 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis The light reactins prduce n sugar; that happens in the secnd stage f phtsynthesis, the Calvin cycle. The Calvin cycle is named fr Melvin Calvin, wh, with his clleagues, wrked ut many f its steps in the 1940s.

20 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis The Calvin cycle begins with the incrpratin f CO 2 int rganic mlecules, a prcess knwn as carbn fixatin. The fixed carbn is reduced with electrns prvided by NADPH. ATP frm the light reactins als pwers parts f the Calvin cycle. Thus, it is the Calvin cycle that makes sugar, but nly with the help f ATP and NADPH frm the light reactins.

21 Phtsynthesis: Phtsynthesis cnverts light energy t the chemical energy f fd 10.1 A preview f the tw stages f phtsynthesis The metablic steps f the Calvin cycle are smetimes referred t as light-independent reactins because nne f the steps requires light directly. Nevertheless, the Calvin cycle in mst plants ccurs during daylight because that is when the light reactins can prvide the NADPH and ATP the Calvin cycle requires. Whereas the light reactins ccur at the thylakids, the Calvin cycle ccurs in the strma. NADPH and ATP are prduced in the thylakids, and then released t the strma, where they play crucial rles in the Calvin cycle.

22 Phtsynthesis: Prcess that Feeds the Bisphere 10.2 The light reactins cnvert slar energy t the chemical energy f ATP and NADPH Light is a frm f electrmagnetic energy r radiatin. Like ther frms f electrmagnetic energy, light travels in rhythmic waves. The distance between crests f electrmagnetic waves is called the wavelength. The mst imprtant segment f the electrmagnetic spectrum fr life is a narrw band between 380 and 750 nm, the band f visible light detected as clrs by the human eye. Althugh light travels as a wave, many f its prperties are thse f a discrete particle, a phtn

23 Phtsynthesis: Prcess that Feeds the Bisphere 10.2 The light reactins cnvert slar energy t the chemical energy f ATP and NADPH Phtns are nt tangible bjects, but d have fixed quantities f energy. The amunt f energy packaged in a phtn is inversely related t its wavelength: Phtns with shrter wavelengths pack mre energy. Althugh the sun radiates a full electrmagnetic spectrum, the atmsphere selectively screens ut mst wavelengths, permitting nly visible light t pass in significant quantities.

24 Phtsynthesis: Prcess that Feeds the Bisphere 10.2 The light reactins cnvert slar energy t the chemical energy f ATP and NADPH Phtns are nt tangible bjects, but d have fixed quantities f energy. The amunt f energy packaged in a phtn is inversely related t its wavelength: Phtns with shrter wavelengths pack mre energy. Althugh the sun radiates a full electrmagnetic spectrum, the atmsphere selectively screens ut mst wavelengths, permitting nly visible light t pass in significant quantities. Visible light is the radiatin that drives phtsynthesis

25 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 Phtsynthetic pigments are light receptrs When light meets matter, it may be reflected, transmitted, r absrbed. Substances that absrb visible light are knwn as pigments. Different pigments absrb phtns f different wavelengths, and the wavelengths that are absrbed disappear. A leaf lks green because chlrphyll, the dminant pigment, absrbs red and vilet-blue light while transmitting and reflecting green light.

26 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 Phtsynthetic pigments are light receptrs The light reactins can perfrm wrk with wavelengths f light that are absrbed. Several pigments in the thylakid differ in their absrptin spectra. Chlrphyll a, which participates directly in the light reactins, absrbs best in the red and viletblue wavelengths and absrbs least in the green. Accessry pigments include chlrphyll b and a grup f mlecules called cartenids

27 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 Phtsynthetic pigments are light receptrs Only chlrphyll a participates directly in the light reactins, but accessry phtsynthetic pigments absrb light and transfer energy t chlrphyll Chlrphyll b, with a slightly different structure than chlrphyll a, has a slightly different absrptin spectrum and funnels the energy frm these wavelengths t chlrphyll. Cartenids can funnel the energy frm ther wavelengths t chlrphyll a and als participate in phtprtectin against excessive light. These cmpunds absrb and dissipate excessive light energy that wuld therwise damage chlrphyll r interact with xygen t frm reactive xidative mlecules that culd damage the cell

28 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 Phtsynthetic pigments are light receptrs Only chlrphyll a participates directly in the light reactins, but accessry phtsynthetic pigments absrb light and transfer energy t chlrphyll Chlrphyll b, with a slightly different structure than chlrphyll a, has a slightly different absrptin spectrum and funnels the energy frm these wavelengths t chlrphyll. Cartenids can funnel the energy frm ther wavelengths t chlrphyll a and als participate in phtprtectin against excessive light. Accessry pigments als prvide access t a brader range f light energy

29 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state When a mlecule absrbs a phtn, ne f the mlecule s electrns is elevated t an rbital with mre ptential energy. The electrn mves frm its grund state t an excited state. The nly phtns that a mlecule can absrb are thse whse energy matches exactly the energy difference between the grund state and the excited state f this electrn.

30 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state When a mlecule absrbs a phtn, ne f the mlecule s electrns is elevated t an rbital with mre ptential energy. The electrn mves frm its grund state t an excited state. The nly phtns that a mlecule can absrb are thse whse energy matches exactly the energy difference between the grund state and the excited state f this electrn. This is why certain pigments can nly absrb specific wavelengths

31 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state In the thylakid membrane, chlrphyll is rganized alng with prteins and smaller rganic mlecules int phtsystems. Phtsystems are cmpsed f a reactin-center cmplex surrunded by light-harvesting cmplexes.

32 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state In the thylakid membrane, chlrphyll is rganized alng with prteins and smaller rganic mlecules int phtsystems. Phtsystems are cmpsed f a reactin-center cmplex surrunded by light-harvesting cmplexes. The reactin-center cmplex is an rganized assciatin f prteins cntaining chlrphyll a mlecules. It acts as an electrn acceptr The light-harvesting cmplexes cntain accessry pigments There are tw phtsystems in these reactins. Phtsystem I and Phtsystem II

33 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state Tgether, the light-harvesting cmplexes act as an antenna fr the reactin-center cmplex. At the reactin center is a primary electrn acceptr, which accepts high energy electrns frm a nearby pigment Chlrphyll a gets it lw energy electrns frm mlecules f H 2 O

34 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state Tgether, the light-harvesting cmplexes act as an antenna fr the reactin-center cmplex. At the reactin center is a primary electrn acceptr, which accepts high energy electrns frm a nearby pigment Chlrphyll a gets it lw energy electrns frm mlecules f H 2 O

35 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state Tgether, the light-harvesting cmplexes act as an antenna fr the reactin-center cmplex. At the reactin center is a primary electrn acceptr, which accepts high energy electrns frm a nearby pigment Chlrphyll a gets it lw energy electrns frm mlecules f H 2 O Light energy is used t energize electrns in chlrphyll a

36 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state Each phtsystem functins in the chlrplast as a unit, cnverting light energy t chemical energy Phtsystem II has a reactin-center chlrphyll a knwn as P680, with an absrptin peak at 680 nm Phtsystem I has a reactin-center chlrphyll a knwn as P700, with an absrptin peak at 700 nm. These tw pigments, P680 and P700, are nearly identical chlrphyll a mlecules. These tw phtsystems wrk tgether in using light energy t generate ATP and NADPH

37 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 When chlrphyll and ther pigments absrb light, an electrn is bsted t an excited state Each phtsystem functins in the chlrplast as a unit, cnverting light energy t chemical energy Phtsystem II has a reactin-center chlrphyll a knwn as P680, with an absrptin peak at 680 nm Phtsystem I has a reactin-center chlrphyll a knwn as P700, with an absrptin peak at 700 nm. These tw pigments, P680 and P700, are nearly identical chlrphyll a mlecules. These tw phtsystems wrk tgether in using light energy t generate ATP and NADPH

38 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic During the light reactins, electrns flw thrugh the phtsystems in the thylakid membrane. 1. Phtsystem II absrbs a phtn f light and an electrn f P680 is excited t a higher energy state. 2. This electrn is captured by the primary electrn acceptr, leaving P680 xidized (P680+).

39 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic During the light reactins, electrns flw thrugh the phtsystems in the thylakid membrane. 1. Phtsystem II absrbs a phtn f light and an electrn f P680 is excited t a higher energy state. 2. This electrn is captured by the primary electrn acceptr, leaving P680 xidized (P680+). 3. An enzyme extracts electrns frm water and transfers them t P680+ (reducing P680 again) This splits water int tw hydrgen ins and an xygen atm (that cmbines with anther xygen atm t frm O 2 ) The H+ are released int the thylakid lumen

40 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic 4. Excited electrns pass frm the PS II t PS I (via an electrn transprt chain). 5. As these electrns fall t a lwer energy level, their energy is harnessed t prduce ATP. This ETC pumps prtns (H+) are pumped int the thylakid lumen, building a prtn gradient that is subsequently used in chemismsis t prduce ATP

41 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic 4. Excited electrns pass frm the PS II t PS I (via an electrn transprt chain). 5. As these electrns fall t a lwer energy level, their energy is harnessed t prduce ATP. This ETC pumps prtns (H+) are pumped int the thylakid lumen, building a prtn gradient that is subsequently used in chemismsis t prduce ATP 6. P700 cllects light energy and uses it t energize the electrns that came frm the ETC in step 4

42 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic 4. Excited electrns pass frm the PS II t PS I (via an electrn transprt chain). 5. As these electrns fall t a lwer energy level, their energy is harnessed t prduce ATP. This ETC pumps prtns (H+) are pumped int the thylakid lumen, building a prtn gradient that is subsequently used in chemismsis t prduce ATP

43 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic 6. Phtsystem I uses accessry pigments t re-energize electrns with light energy 7. Phtexcited electrns are passed dwn a secnd electrn transprt chain 8. These electrns reduce NADP+ t frm NADPH. NADPH will carry the reducing pwer f these highenergy electrns t the Calvin cycle What is the purpse f Phtsystem I? Its purpse is t replace energy used t prduce sme ATP! At the end f the light reactins we nw have bth ATP and NADPH t prduce carbhydrates!

44 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 During the light reactins, there are tw pssible rutes fr electrn flw: linear and cyclic The light reactins use the slar pwer f phtns absrbed by PS II and PS I t prvide chemical energy in the frm f ATP and reducing pwer in the frm f the electrns carried by NADPH t the carbhydrate-synthesizing reactins f the Calvin cycle.

45 Phtsynthesis: The light reactins cnvert slar energy t the chemical energy f ATP and NADPH 10.2 Chlrplasts and mitchndria generate ATP by the same mechanism: chemismsis In bth chlrplasts and mitchndria, an electrn transprt chain pumps prtns acrss a membrane as electrns are passed alng a series f increasingly electrnegative carriers. This prcess transfrms redx energy t a prtn-mtive frce in the frm f an H+ gradient acrss the membrane. ATP synthase mlecules harness the prtn-mtive frce t generate ATP as H+ diffuses back acrss the membrane Sme f the electrn carriers, including the cytchrmes, are similar in chlrplasts and mitchndria. The ATP synthase cmplexes f the tw rganelles are als very similar

46 Phtsynthesis: Prcess that Feeds the Bisphere 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar The Calvin cycle regenerates its starting material after mlecules enter and leave the cycle. The Calvin cycle is anablic, using energy t build sugar frm smaller mlecules. Carbn enters the cycle as CO 2 and leaves as sugar. The cycle spends the energy f ATP and the reducing pwer f electrns carried by NADPH t make sugar. The actual sugar prduct f the Calvin cycle is nt glucse but a three-carbn sugar, glyceraldehyde-3-phsphate (G3P). Each turn f the Calvin cycle fixes ne carbn

47 Phtsynthesis: Prcess that Feeds the Bisphere 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar Phase 1: Carbn fixatin In the carbn fixatin phase, each CO 2 mlecule is attached t a five-carbn sugar, ribulse bisphsphate (RuBP). This reactin is catalyzed by RuBP carbxylase-xygenase, r Rubisc. Rubisc is the mst abundant prtein in chlrplasts and prbably the mst abundant prtein n Earth. The six-carbn intermediate is unstable and splits in half t frm tw mlecules f 3-phsphglycerate fr each CO 2 fixed

48 Phtsynthesis: Prcess that Feeds the Bisphere 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar Phase 2: Reductin Fr every three mlecules f CO 2 that enter the cycle, there are six mlecules f G3P frmed. One f these six G3P is a net gain f carbhydrate. This is because it takes 3 carbn atms t prduce a single G3P

49 Phtsynthesis: Prcess that Feeds the Bisphere 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar Glyceraldehyde-3-phsphate (G3P) is a cnnectin t numerus metablic pathways G3P is the starting material fr metablic pathways that synthesize ther rganic cmpunds, including glucse and ther carbhydrates.

50 Phtsynthesis: Prcess that Feeds the Bisphere 10.3 The Calvin cycle uses the chemical energy f ATP and NADPH t reduce CO 2 t sugar Glyceraldehyde-3-phsphate (G3P) is a cnnectin t numerus metablic pathways G3P is the starting material fr metablic pathways that synthesize ther rganic cmpunds, including glucse and ther carbhydrates.