Qhov sib txawv tseem ceeb ntawm C3 thiab C4 cov nroj tsuag yog tias cov nroj tsuag C3 tsim muaj peb-carbon compound ua thawj cov khoom ruaj khov ntawm cov tshuaj tiv thaiv tsaus ntuj thaum C4 cov nroj tsuag tsim plaub-carbon compound ua thawj cov khoom ruaj khov ntawm tsaus ntuj.
Photosynthesis yog txheej txheem teeb tsa uas hloov cov pa roj carbon dioxide thiab dej rau hauv cov suab thaj uas muaj zog hauv cov nroj tsuag, algae thiab cyanobacteria. Thaum lub teeb pom kev ntawm photosynthesis, photolysis ntawm dej molecules tshwm sim. Raws li qhov tshwm sim ntawm photolysis ntawm dej, oxygen liberates raws li ib tug byproduct. Tom qab cov tshuaj tiv thaiv lub teeb, cov tshuaj tiv thaiv tsaus pib thiab nws synthesizes carbohydrates los ntawm kev kho cov pa roj carbon dioxide. Txawm li cas los xij, cov pa oxygen tsim los ntawm lub teeb pom kev tuaj yeem khi nrog lub ntsiab enzyme ntawm cov tshuaj tiv thaiv tsaus ntuj uas yog RuBP oxygenase-carboxylase (Rubisco) thiab nqa tawm photorespiration. Photorespiration yog txheej txheem uas nkim lub zog thiab txo cov carbohydrate synthesis. Yog li ntawd, txhawm rau tiv thaiv photorespiration, muaj peb txoj hauv kev sib txawv uas cov tshuaj tiv thaiv tsaus ntuj tshwm sim hauv cov nroj tsuag los tiv thaiv lub rooj sib tham ntawm oxygen nrog Rubisco. Li no, nyob ntawm txoj kev tsaus ntuj tshwm sim, muaj 3 hom nroj tsuag; xws li, C3 nroj tsuag, C4 nroj tsuag, thiab CAM nroj tsuag.
C3 Nroj tsuag yog dab tsi?
Kwv yees li 95% ntawm cov nroj tsuag hauv ntiaj teb yog C3 nroj tsuag. Raws li lub npe qhia, lawv nqa tawm C3 photosynthetic mechanism uas yog Calvin voj voog. C3 photosynthesis tau xav tias tau tshwm sim ze li 3.5 billion xyoo dhau los. Cov nroj tsuag no feem ntau yog woody thiab round nplooj ntoo. Hauv cov nroj tsuag no, carbon fixation tshwm sim nyob rau hauv mesophyll hlwb uas nyob hauv qab lub epidermis.
Cov pa roj carbon dioxide nkag los ntawm huab cua mus rau mesophyll hlwb los ntawm stomata. Ces qhov tsaus ntuj tshwm sim pib. Thawj cov tshuaj tiv thaiv yog kho cov pa roj carbon dioxide nrog Ribulose bisphosphate rau hauv phosphoglycerate uas yog peb-carbon compound. Qhov tseeb, nws yog thawj cov khoom ruaj khov ntawm cov nroj tsuag C3. Ribulose bisphosphate carboxylase (Rubisco) yog lub enzyme uas catalyzes cov tshuaj tiv thaiv carboxylation hauv cov nroj tsuag. Ib yam li ntawd, lub voj voog Calvin tshwm sim cyclically thaum tsim cov carbohydrates.
Daim duab 01: C3 Nroj tsuag
Y Piv rau C4 nroj tsuag, C3 nroj tsuag tsis muaj txiaj ntsig txog lawv cov txheej txheem photosynthetic. Nws yog vim qhov tshwm sim ntawm photorespiration hauv C3 nroj tsuag. Photorespiration tshwm sim vim muaj oxygenase kev ua ntawm Rubisco enzyme. Oxygenation ntawm Rubisco ua hauj lwm nyob rau hauv lub opposite kev taw qhia rau carboxylation, ua tau zoo undoes photosynthesis los ntawm nkim ntau cov pa roj carbon qub qub kho los ntawm Calvin lub voj voog ntawm tus nqi zoo, thiab ua rau poob ntawm carbon dioxide los ntawm cov hlwb uas kho cov pa roj carbon dioxide. Ib yam li ntawd, kev sib cuam tshuam nrog oxygen thiab carbon dioxide tshwm sim ntawm tib qhov chaw ntawm Rubisco. Cov kev sib tw sib tw no nquag khiav ntawm qhov sib piv ntawm 3: 1 (carbon: oxygen). Yog li, nws yog qhov tseeb tias photorespiration yog ib qho kev txhawb nqa lub teeb uas siv cov pa oxygen thiab hloov pauv carbon dioxide.
C4 Nroj tsuag yog dab tsi?
C4 cov nroj tsuag muaj nyob rau hauv qhov chaw qhuav thiab kub. Kwv yees li 1% ntawm cov nroj tsuag muaj C4 biochemistry. Qee qhov piv txwv ntawm C4 nroj tsuag yog pob kws thiab qab zib. Raws li lub npe qhia, cov nroj tsuag no ua haujlwm C4 photosynthetic mechanism. C4 photosynthesis xav tias tau tshwm sim ze li ntawm 12 lab xyoo dhau los; ntev tom qab lub evolution ntawm C3 mechanism. C4 cov nroj tsuag tuaj yeem hloov kho tau zoo dua tam sim no, vim tias cov pa roj carbon dioxide tam sim no qis dua 100 lab xyoo dhau los.
C4 cov nroj tsuag muaj txiaj ntsig zoo dua ntawm kev ntes cov pa roj carbon dioxide. Tsis tas li ntawd, C4 photosynthesis muaj nyob rau hauv ob hom monocot thiab dicot. Nyob rau hauv sib piv rau C3 nroj tsuag, thawj ruaj khov khoom tsim thaum lub sij hawm photosynthesis yog oxaloacetic acid, uas yog ib tug plaub-carbon compound. Qhov tseem ceeb tshaj plaws, cov nplooj ntawm cov nroj tsuag no qhia ib hom kev kho mob tshwj xeeb hu ua "Kranz Anatomy". Muaj ib lub voj voog ntawm cov ntaub qhwv cov cell nrog chloroplasts nyob ib ncig ntawm cov hlab ntsha uas C4 cov nroj tsuag tuaj yeem txheeb xyuas.
Daim duab 02: C4 Nroj tsuag
Nyob hauv txoj kev no, kev kho carbon dioxide tshwm sim ob zaug. Nyob rau hauv mesophyll cell cytoplasm, CO2 thawj kho nrog phosphoenolpyruvate (PEP), uas ua raws li thawj qhov txais. Cov tshuaj tiv thaiv yog catalyzed los ntawm PEP carboxylase enzyme. Tom qab ntawd PEP hloov mus rau hauv malate thiab tom qab ntawd mus rau hauv pyruvate liberating CO2 Thiab, qhov CO2rov kho dua zaum ob nrog Ribulose bisphosphate, tsim 2. phosphoglycerate ua rau Calvin lub voj voog.
Dab tsi zoo sib xws ntawm C3 thiab C4 Nroj Tsuag?
- Ob C3 thiab C4 cov nroj tsuag kho cov pa roj carbon dioxide thiab tsim cov carbohydrates.
- Lawv ua rau tsaus ntuj nti.
- Tsis tas li ntawd, ob hom nroj tsuag muaj tib lub teeb pom kev zoo.
- Tsis tas li ntawd, lawv muaj chloroplasts los ua cov photosynthesis.
- Lawv cov kab zauv photosynthetic zoo ib yam.
- Ntxiv mus, RuBP cuam tshuam nrog cov tshuaj tiv thaiv tsaus ntawm ob hom nroj tsuag.
- Ob tsob nroj tsim phosphoglycerate.
Qhov txawv ntawm C3 thiab C4 Nroj Tsuag yog dab tsi?
C3 nroj tsuag tsim phosphoglyceric acid ua thawj cov khoom ruaj khov ntawm cov tshuaj tiv thaiv tsaus. Nws yog peb-carbon compound. Ntawm qhov tod tes, C4 cov nroj tsuag tsim oxalo-acetic acid ua thawj cov khoom ruaj khov ntawm cov tshuaj tiv thaiv tsaus. Nws yog plaub-carbon compound. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm C3 thiab C4 nroj tsuag.
Tsis tas li ntawd, photosynthetic efficiency ntawm C3 nroj tsuag yog tsawg dua cov photosynthetic efficiency ntawm C4 nroj tsuag. Nws yog vim photorespiration pom nyob rau hauv C3 nroj tsuag uas yog negligible nyob rau hauv C4 nroj tsuag. Yog li, nws yog lwm qhov sib txawv ntawm C3 thiab C4 nroj tsuag. Thaum xav txog qhov sib txawv ntawm cov qauv, C3 nroj tsuag tsis muaj ob hom chloroplasts thiab Kranz anatomy hauv nplooj. Ntawm qhov tod tes, C4 nroj tsuag muaj ob hom chloroplasts, thiab lawv qhia Kranz anatomy hauv nplooj. Li no, nws kuj yog qhov txawv ntawm C3 thiab C4 nroj tsuag.
Ntxiv mus, qhov sib txawv ntxiv ntawm C3 thiab C4 cov nroj tsuag yog tias cov nroj tsuag C3 kho cov pa roj carbon dioxide ib zaug thaum C4 cov nroj tsuag kho cov pa roj carbon dioxide ob zaug. Vim qhov tseeb no, C assimilation tsawg dua hauv C3 nroj tsuag thaum C assimilation siab hauv C4 nroj tsuag. Tsis tas li ntawd xwb, C4 cov nroj tsuag tuaj yeem nqa tawm photosynthesis thaum lub stomata raug kaw thiab nyob rau hauv lub teeb siab heev thiab qis CO 2 concentrations. Txawm li cas los xij, C3 cov nroj tsuag tsis tuaj yeem nqa tawm photosynthesis thaum lub stomata raug kaw thiab nyob rau hauv lub teeb siab heev thiab qis CO 2 concentrations. Yog li, qhov no kuj yog qhov sib txawv tseem ceeb ntawm C3 thiab C4 nroj tsuag. Tsis tas li ntawd, C3 nroj tsuag thiab C4 nroj tsuag txawv ntawm thawj carbon dioxide txais. RuBP yog tus CO2 lees txais hauv C3 nroj tsuag thaum PEP yog thawj CO2 lees txais hauv C4 nroj tsuag.
Summary – C3 vs C4 Nroj tsuag
C3 thiab C4 yog ob hom nroj tsuag. C3 nroj tsuag muaj ntau heev thaum C4 nroj tsuag tsis tshua muaj heev. Qhov sib txawv tseem ceeb ntawm C3 thiab C4 cov nroj tsuag nyob ntawm thawj cov khoom carbon uas lawv tsim thaum lub sijhawm tsaus ntuj. C3 nroj tsuag nqa tawm lub voj voog Calvin thiab tsim peb-carbon compound ua thawj cov khoom ruaj khov thaum C4 cov nroj tsuag nqa tawm C4 mechanism thiab tsim plaub carbon compound ua thawj cov khoom ruaj khov. Tsis tas li ntawd, cov nroj tsuag C3 qhia tsawg dua photosynthetic efficiency thaum C4 nroj tsuag qhia siab photosynthetic efficiency. Ntxiv mus, C3 nroj tsuag tsis muaj Kranz anatomy nyob rau hauv nplooj, thiab lawv kuj tsis muaj ob hom chloroplasts. Ntawm qhov tod tes, C4 nroj tsuag muaj Kranz anatomy hauv lawv cov nplooj, thiab lawv kuj muaj ob hom chloroplasts. Yog li, qhov no yog cov ntsiab lus ntawm C3 thiab C4 nroj tsuag.
