Embed Size (px)
Citation preview
9/1/2016
1
http://cnx.org/resources/722dad908853869fdd3c65bf0fc65a46/Figure_08_03_02f.png
LECTURE OUTCOMESStudents, after mastering materials of thepresent lecture, should be able:1. To explain the mechanism of CO2 assimilation to be
carbohydrate (sugars)2. To explain the diffusion of CO2 from the atmosphere
into the site of CO2 assimilation in the chloroplasts3. To explain reactions, enzymes and products involved in
the reduction of CO2 to be carbohydrate in C3 Plants
29/1/2016
9/1/2016
2
1. What is the first event in the formation ofcarbohydrate from CO2 ?2. What is the first reaction in the reduction ofCO2 to be (CH2O)n ?3. What is the molecule or compound that bindsor reacts with CO2 ?4. What is the first product of CO2 reduction inphotosynthesis ?5. How was it known that a particular productwas the first compound formed inphotosynthesis
6. What is the enzyme catalyzing the first reactionof CO2 reduction ?7. How many RUBP required to reduce 1 mol CO2in photosynthesis8. How many are ATP and NADPH required toreduce 1 mol CO2 in photosynthesis9. Based on ATP and NADP requirement, howmuch is light required to reduce 1 mol CO2 inphotosynthesis10. How many mol are CO2 reduced per mol H2Obroken down in the photolysis ofphotosynthesis
9/1/2016
3
1. What is the first event in the formationof carbohydrate from CO2 ?AnswerDiffusion of CO2 from the atmosphereinto the chloroplast
9/1/2016
4
Evans et al., 2009
C3 plants
9/1/2016
5
C3 plants
9/1/2016
6
Analisis Fluks CO2 dengan pendekatandifusi Analisis Fluks CO2 dengan pendekatanresisten (tahanan)
xC
DF
aSm
CA
rrr
CCF
Difusi CO2
IlustrasiSoal : Diketahui rm = 100 m.s-1, ra = 500 m.s-1 & rs= 800 m.s-1, dan [CO2] = 400 ml.l-1 di atmosfirpada suhu 250C. Dalam khloroplast, [CO2]dianggap nol. Berapakah fluks CO2 ke dalamkhloroplast dari atmosfirJawab[CO2] = 400 ml.l-1= (400/106)*1000 liter.m-33
2 .719,044414,22
273
)25273(4.0
][
mgCO
1221
3
2 .514,0.000514,0.)800500100(
.)0719,0()(
smmgmgsm
mgCOF
9/1/2016
7
2. What is the first reaction in thereduction of CO2 to be (CH2O)n ?• The reaction of CO2 with RUBP in C3plants, and the reaction of CO2 with PEP inC4 and CAM plants3. What is the molecule or compound thatbinds or reacts with CO2 ?• RUBP in C3 plants and PEP in C4 and CAMplants
Ribulose 1,5bisphosphate
3-phosphoglycerate(PGA)
Triosephosphate
Sucrose
From the lightreaction of
photosynthesisATP
AtmosphericCO2
NADPHNADP+
ADP + Pi
C3 PCA
Fixation
C3 plants
9/1/2016
8
C4 plants
Ribulose 1,5bisphosphate
3-phosphoglycerate(PGA)
Triosephosphate
Sucrose
From the lightreaction of
photosynthesisATP
AtmosphericCO2
NADPHNADP+
ADP + Pi
C3 PCA
Fixation
C3 plants
C4 plants
9/1/2016
9
4. What is the first product of CO2 reductionin photosynthesis ?
RUBPRibulose
1,5-bisphosphate
CH2OPO32-
CO
HCOH
HCOH
CH2OPO32-
1
2
3
4
5
CH2OPO32-
HOC*CO2-
HCOH
HCOH
CH2OPO32-
1
2
3
4
5
*CO2
C
*H2O
C
CH2OPO32-
HC*CO2-
OH
1
2
CO2-
HCOH
CH2OPO32-
3
4
52 Carboxy-3-ketoarabinitol1,5-bisphosphate(a transient, unstableenzyme-bound intermediate)
3-Phosphoglycerate
Carboxylation Hydrolysis
Labeling Study of carbon compounds in thealga Chorella after exposure to 14CO2. It was found that 3-phosphoglyceric acid(PGA) was the heavyly labeled compoundafter shortest exposure This indicates that it is the first stableintermediate of the PCR cycle. (FromBassham, 1965.)
5. How was it known that a particularproduct was the first compound formed inphotosynthesis
9/1/2016
10
5 SECONDS 10 SECONDS
30 SECONDS
6. What is the enzyme catalyzing the firstreaction of CO2 reduction ?7. How many RUBP required to reduce 1 molCO2 in photosynthesisTAHAPANREDUKSI CO21. Carboxylation2. Reduction3. Regeneration
9/1/2016
11
TAHAPAN REDUKSI CO21. Carboxylation2. Reduction3. Regeneration
9/1/2016
12
PPFD = Photosynthetic Photon Flux DensityCER = CO2 Exchange Rate (net photosynthesis)
-5
0
5
10
15
20
25
30
0 500 1000 1500 2000
CER
(m
ol C
O2
m-2
s-1 )
PPFD (mol m-2 s-1)
Results of measurements of net photosynthesis (CER) of32 soybean genotypes and 1 variety in Malang
-5
0
5
10
15
20
25
30
0 500 1000 1500 2000
CER
(mol
CO
2m
-2s-
1 )
PPFD (mol m-2 s-1)
maxmax .1 PIQEXPPP E
Pmax = 29.5 mol CO2 m-2 s-1
QE = 0.0494 mol CO2 m-2 s-1/(mol photon m-2 s-1)
9/1/2016
13
ENZIM YANG TERLIBAT
9/1/2016
14
9/1/2016
15
9/1/2016
16
9/1/2016
17
8. How many are ATP and NADPH required toreduce 1 mol CO2 in photosynthesis9. Based on ATP and NADP requirement, howmuch is light required to reduce 1 mol CO2in photosynthesis10. How many mol are CO2 reduced per molH2O broken down in the photolysis ofphotosynthesis
9/1/2016
18
6 (ribulose 1,5 bisP) + 6CO2 + 6H2O 12 (3-P-glycerate) + 12H+
12 (3-P-glycerate) + 12ATP 12 (1,3-bisP-glycerate) + 12ADP
12 (1,3-bisP-glycerate) + 12 (NADPH + H+) 12 (triose-P) + 12 NADP+ + 12 Pi
6 (triose-P) 3 (fructose 1,6-bisP)
3 (fructose 1,6-bisP) + 3 H2O 3 (fructose 6-P) + 3 Pi
2 (fructose 6-P) + 2 (triose-P) 2 (xylulose 5-P) + 2 (erythrose 4-P)
2 (erythrose 4-P) + 2 (triose-P) 2 (sedoheptulose 1,7-bisP)
2 (sedoheptulose 1,7-bisP) + 2 (triose-P) 2 (xylulose 5-P) + 2 (ribulose 5-P)
4 (xylulose 5-P) 4 (ribulose 5-P)
2 (ribose 5-P) 2 (ribulose 5-P)
6 (ribulose 5-P) + 6ATP 6 (ribulose 1,5-bisP) + 6ADP
Net: 6CO2 + 11H2O + 12NADPH + 18ATP fructose 6-P + 12 NADP+ + 6H+ + 18ADP + 17Pi
6CO2+11H2O+12NADPH+18ATPF 6-P+ 12NADP++6H++18ADP+17Pi
CO2+(11/6)H2O+2NADPH+3ATP1/6 F 6-P+ 2NADP++H++3ADP+(17/6)Pi
The reduction cost of 1 mol CO2 =2mol NADPH+3 mol ATP
9/1/2016
19
PHOTORESPIRATIONFotorespirasi adalah pengeluaranCO2 dari tanaman akibat reaksi enzimRibulose 1,5 bisphosphate oxygenasedengan oksigen (O2)
Photorespiration
9/1/2016
20
9/1/2016
21
9/1/2016
22
ENERGETIC COSEQUENCE OFPHOTORESPIRATIONEnergetic consequence of carboxylating RuBP3CO2+3H2O+9ATP+6[NAD(P)H+H+]triose-P+9ADP+6[NAD(P)+]Cost of fixing one CO2 : 3ATP+2[NAD(P)H+H+]
Energetic consequence of oxygenating RuBPR-5P+O2+2ATP+2.5[NAD(P)H+H+]0.9(R-5P)+0.5CO2+2ADP+2.5[NAD(P)+]+2PiCost of fixing one O2 : 2ATP+2.5[NAD(P)H+H+]Total cost (3CO2/O2): 11ATP+8.5[NAD(P)H+H+]
9/1/2016
23
