QUANG HÔÏP
PHA TOÁI
Photosynthesis
Pha thu nhaän saûn phaåm pha saùng (ATP + NADPH) ñeå toång hôïp höõu cô (Carbohydrate) [khoâng phuï thuoäc vaøo aùnh saùng]
Photosynthesis: h 6CO2 + 6H2O C6H12O6 + 6O2 Chlorophyll
Calvin cycle Calvin cycle
Quang hôïp nhoùm thöïc vaät C3
phosphoglycerate fixation is 3--phosphoglycerate
The first product of CO22 fixation is 3 The first product of CO
14CO2
pump
M. Calvin & A. Benson exposed green algae to 14CO2 for short periods of time in the presence of light. They separated and identified the labeled products by paper chromatography.
algae
boiling methanol
light
14CO2 -
14C appeared first in the carboxyl carbon of 3-phosphoglycerate.
H-C-OH
CH2-O- P
1
CHUOÃI CAÙC PHAÛN ÖÙNG ÑOÀNG HOÙA CARBON C3
Light-dependent reactions Carbon fixation reactions
Chloroplast
Lig ht reacti o ns
Calvi n cycl e
C6H12O6 + 6O2
6 molecules of CO2
6CO2 + 6H2O (6C) 6 CO2
6 x 5C = 30C
CO2 molecules are captured by RuBP1 resulting in an unstable intermediate that is immediately broken apart into 2 PGA
6 molecules of ribulose bisphosphate (RuBP)
36C 12 molecules of Phosphoglycerate (PGA)
CO2 uptake phase
30C
12 ATPs
6 molecules of ribose phosphate (RP)
CALVIN CYCLE
12 ADPs
RuBP regeneration phase
Carbon reduction phase
12 NADPH,H+
12 NADP
6C Glucose and other carbohydrate synthesis
PGA is phosphorylated by ATP and reduced by NADPH.
12 molecules of glyceraldehyde-3- phosphate (G3P) 36C
12 molecules of glyceraldehyde-3- phosphate (G3P)
2
The Benson-Calvin cycle
An An antiporter
antiporter exchanges Pi with
exchanges Pi with triose
phosphates triose phosphates
3CO2
3ATP
carboxylation
regeneration
3 RuBP 3 x C5
6ATP + 6 NADPH
reduction
6 glycerate 3-P (6 x C3) 5 x C3
Ribulose 1,5 Bisphosphate Carboxylase/Oxidase
1 x C3 product 6 triose-P (6 x C3)
RUBISCO:
trong enzyme ññooùùngng vaivai trotroøø quanquan trotroïïngng trong CaCaùùcc enzyme chuchu trtrììnhnh Calvin Calvin ñöñöôôïïcc ññieieààuu hohoøøaa bôbôûûii aaùùnhnh sasaùùngng::
Glyceraldehyde 33--phosphate dehydrogenase phosphate dehydrogenase
NhạNhạy cy cảảm vm vớới i áánh snh sááng mng mạạnhnh i CO2 th thấấpp ÁÁi li lựực vc vớới CO2 Không chịịu nhi u nhiệệt đt độ ộ caocao Không ch nh 2 mmặặt: t: TíTính 2
Rubisco Rubisco NADP: Glyceraldehyde NADP: bisphosphatase Fructose 1,6--bisphosphatase Fructose 1,6 bisphosphatase Sedoheptulose 1,7 1,7 bisphosphatase Sedoheptulose kinase phosphate kinase Ribulose 55--phosphate Ribulose thoâng qua qua vievieääcc hhììnhnh thathaøønhnh hay hay phaphaùù boboûû CôCô checheáá ññieieààuu hohoøøaa ththööôôøøngng thoâng disulfide cacaùùcc lieânlieân kekeáátt disulfide
Rubisco gaén vaøo cô chaát
•• CO2CO2 •• O2O2
>>> Quang hô h >>> Qua ng hô hấấp >p >>> kh >> không nh ng không tạạo o ông nhữững không t n phân hủủy đy đườường đng đã tíã tích lch lũũyy đđườường mng mà còà còn phân h
3
HIEÄN TÖÔÏNG QUANG HOÂ HAÁP
RRibibuuloselose 1,51,5--bisbisphosphate
phosphate ccarboxylase
arboxylase--ooxygenase
Rubisco)) xygenase ((Rubisco
Enzyme RUBISCO xuùc taùc phaûn öùng vôùi oxygen gaây ra hieän töôïng quang hoâ haáp
C5 + C1 2 x C3 carboxylase RuBP + CO2 + H2O 2 (glycerate 3-P)
C3 + C2 C5 RuBP + O2 glycerate 3-P + glycollate 2-P oxygenase
4
Photorespiratory pathway
Photorespiratory pathway/Quang hoâ haáp
2 glycollate-2-P
2 glycollate
2 glycine (C2)
2 glycollate-2-P
2 glycollate
2 glycine (C2)
2 x C2 2 x C2 1 x C3 + CO2 1 x C3 + CO2
peroxisome
peroxisome
Rubisco
Rubisco
glycine decarboxylase
glycine decarboxylase
CO2 NH3
mitochondrion
CO2 NH3 NADH
mitochondrion
NADH
chloroplast
chloroplast
peroxisome
peroxisome
glycerate-3-P
serine (C3)
glycerate-3-P
serine (C3)
5
CHUOÃI PHAÛN ÖÙNG QUANG HOÂ HAÁP
Glyoxylate
From Chloroplasts
O2
CHO
Why Photorespiration? Why Photorespiration?
COO
Mitochondria
CH2OH COO Glycolate
+
1. O2 (21% of air) is more prevalent than CO2 (0.03%)
NH3 2
Glycerate
CH2NH3 COO
2. RUBISCO reacts with O2 (Km =200 M)
CH2NH3 COO
as well as CO2 (Km=20 M)
Glycine CH2OH CHOH COO CO2 ATP
NAD+
RUBISCO IS BOTH AN OXYGENASE and a CARBOXYLASE
+
NH3
NADH
3. Phosphoglycolate can be salvaged.
3PGA Glycine Serine (mitochondria)releases CO2 Glycolate Glyoxylate (peroxisomes) consumes O2 CH2OH C=O COO CH2OH CHNH3 COO CH2OH CHNH3 COO Serine
Peroxisomes
Hydroxy
O2 in CO2 out is respiration
pyruvate
QUANG HÔÏP
Quang hô hấp làm giảm hiệu quả quang hợp và là điều không mong muốn trong canh tác nông nghiệp.
QUANG HOÂ HAÁP
to cao
Tại sao hiện tượng quang hô hấp tồn tại: - Chức năng bảo vệ !!! - Ngăn ngừa sự hình thành gốc oxi hóa tự do
6
Quang hôïp nhoùm thöïc vaät C4
Species Species
Family Family
Zea mays Zea mays
Poaceae Poaceae
Maydeae Maydeae
Andropogon scoparius Andropogon scoparius
Andropogoneae Andropogoneae
Andropogon virginicus Andropogon virginicus
Saccharum spp. Saccharum spp.
Sorghum spp. Sorghum spp.
Panicum antidotale Panicum antidotale
Paniceae Paniceae
Panicum maximum Panicum maximum
Panicum miliaceum Panicum miliaceum
Panicum texacum Panicum texacum
Digitaria decumbens Digitaria decumbens
Digitaria sanguinalis Digitaria sanguinalis
Cynodon dactylon Cynodon dactylon
Chlorideae Chlorideae
Eragrostis curvula Eragrostis curvula
Festuceae Festuceae
Sporobolus poiretii Sporobolus poiretii
Agrostidae Agrostidae
Spartina towensendii Spartina towensendii
Graminae Graminae
Amaranthus edulis Amaranthus edulis
Amaranthaceae Amaranthaceae
Amaranthus retroflexus Amaranthus retroflexus
Atriplex confertifolia Atriplex confertifolia
Chenopodiaceae Chenopodiaceae
Atriplex lentiformis Atriplex lentiformis
Mesophyll cell
CO2
CHUOÃI CAÙC PHAÛN ÑOÀNG HOÙA CARBON C4
(3C)
Oxaloacetate
(4C)
Phosphoenol- pyruvate
NADPH
ADP
NADP+
ATP
Pyruvate
Malate
(4C)
(3C)
ADP
(3C)
Pyruvate
Malate
(4C)
NADP+
Bundle sheath cell
CO2
NADPH
Glucose
Vein
7
CHUOÃI CAÙC PHAÛN ÑOÀNG HOÙA CARBON C4
Caáu truùc laù
2ATP/CO2
Thöïc vaät C3 Thöïc vaät C4
Water regulation in plants Water regulation in plants
Physiological solutions Physiological solutions C4 photosynthesis C4 photosynthesis
How do organisms ‘solve’ common problems?
How do organisms ‘solve’ common problems?
8
Söï hieän dieän cuûa mRNA mang thoâng tin di truyeàn toång hôïp enzyme RUBISCO ôû caây C4.
9
Leaf Anatomy CC44 Leaf Anatomy
CC44 Photosynthesis:
Pump”” Photosynthesis: ““COCO22--Pump
epidermis
4C acid
4C acid
CO2
X P
mesophyll cells
CO2
PEPcase
CO2
3C
3C
bundle sheath cells
epidermis
mesophyll cell
bundle- sheath cell
C4 Photosynthesis: “CO2-Pump”
ÑÑIEIEÅÅM BUM BUØØ CO2 TH T C3 & C4 CO2 THÖÏÖÏC VAC VAÄÄT C3 & C4
140
PEPcase is used for
120
100
C4 - corn
Carboxylation in the mesophyll
80
e t a R S P e v
60
l
40
i t a e R
C3 - beans
20
Rubisco is used for
0
0
10
50
100 200 300 400 500 600 800
CO2 Concentration (ppm)
Carboxylaton (in the Calvin cycle) in bundle sheath
CO2 compensation points: C4 = 10 ppm & C3 = 50 ppm
Compensation Point COCO22 Compensation Point
Quang hôïp nhoùm thöïc vaät trao ñoåi acid crassulacean
] where PS rate = 0 Equals the [CO22] where PS rate = 0
Equals the [CO CC33 plants usually between 50 and 100 ppm plants usually between 50 and 100 ppm plants can be as low as 5 to 15 ppm CC44 plants can be as low as 5 to 15 ppm
(Crassulacean Acid Metabolism: CAM)
10
Typical CAM plants
Pineapple (bromeliad)
saguaro cactus
Rhipsalis (epiphytic cactus)
Opuntia (prickly pear)
epiphytic orchids
Agave tequilana
Tillandsia usneoides (Spanish moss)
Crassulacean Acid Metabolism (CAM)
CO2
CAMCAM
HCO3 -
RuBP
Calvin cycle
CHO
C3
C4
CO2
CO2
ÑEÂM (khí khoång môû) NGAØY(khí khoång ñoùng)
CHO
C3
C4
Vacuole
C4
CO2 C-C-C-C Malate C-C-C-C Malate C-C-C-C Malate
C4
vacuole
vacuole
CO2 C3
ATP
glucose
C-C-C C-C-C PEP NIGHT DAY Pyruvic acid
11
Chuyeån hoùa carbon quang hôïp ôû thöïc vaät CAM
