• Proses Pembentukan Senyawa Kompleks Dari Senyawa
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Transcript of • Proses Pembentukan Senyawa Kompleks Dari Senyawa
Anabolisme
• Proses pembentukan senyawa kompleks dari senyawa sederhana dengan bantuan enzim.
• Memerlukan energi reaksi endergonik• Contoh : Fotosintesis
Fotosintesis
• Sintesis zat organik (glukosa) dari zat anorganik (air dan karbondioksida) dengan bantuan cahaya matahari
• Terjadi pada organ tumbuhan yang memiliki klorofil dalam kloroplas.
• Terdapat beberapa jenis pigmen : klorofil a (pigmen hijau mampu menyerap cahaya merah dan biru ungu serta memantulkan cahaya hijau), klorofil b (pigmen hijau kuning menyerap cahaya biru dan jingga), dan karotenoid (pigmen kuning jingga menyerap cahaya biru-hijau).
Penelitian Fotosintesis• Jan Ingenhouz (adanya gas oksigen)• Nicholas de Saussure (pertambahan berat)• Samuel Ruben dan Martin Kamen (Oksigen yang
dihasilkan berasal dari air)• Julius Robert Mayer (absorbsi energi dalam
bentuk energi cahaya energi kimia (ATP/NADH)
• Daniel Arnon organ fotosintesis (memisahkan kloroplas)
• Van Niel 2 reaksi fotosintesis (terang dan gelap)
Chloroplasts: The Sites of Photosynthesis in Plants
• The leaves of plants– Are the major sites of photosynthesis
Vein
Leaf cross section
Figure 10.3
Mesophyll
CO2 O2Stomata
• Chloroplasts– Are the organelles in which photosynthesis occurs– Contain thylakoids and grana
Chloroplast
Mesophyll
5 µm
Outermembrane
Intermembranespace
Innermembrane
Thylakoidspace
ThylakoidGranumStroma
1 µm
The Splitting of Water• Chloroplasts split water into– Hydrogen and oxygen, incorporating the electrons
of hydrogen into sugar molecules
6 CO2 12 H2OReactants:
Products: C6H12O66 H2O 6 O2
Figure 10.4
Reaksi Terang• Terjadi di grana• Disebut fotolisis karena menguraikan air oleh matahari.• Energi cahaya ditangkap molekul pigmen fotosintesis yang
tersusun dalam satu bagian yang disebut fotosistem (I dan II), partikel FS I di lamela intergrana, sedang FS II di membran grana.
• Tiap fotosistem mengandung molekul klorofil/ pigmen aksesori (karotenoid atau xantofil). Sedang molekul klorofil utama adalah klorofil a pigmen primer (FS I = P700 nm dan FS II = P680 nm).
• Pada reaksi terang terjadi fotofosforilasi (pelepasan elektron akibat cahaya matahari). Ada dua fotofosforilasi (siklik dan non siklik)
– Reflect light, which include the colors we see
Light
ReflectedLight
Chloroplast
Absorbedlight
Granum
Transmittedlight
Figure 10.7
• The electromagnetic spectrum– Is the entire range of electromagnetic energy, or radiation
Gammarays X-rays UV Infrared
Micro-waves
Radiowaves
10–5 nm 10–3 nm 1 nm 103 nm 106 nm1 m
106 nm 103 m
380 450 500 550 600 650 700 750 nm
Visible light
Shorter wavelength
Higher energy
Longer wavelength
Lower energyFigure 10.6
• The absorption spectra of three types of pigments in chloroplasts Three different experiments helped reveal which wavelengths of light are photosynthetically important. The results are shown below.
EXPERIMENT
RESULTSAb
sorp
tion
of li
ght b
ych
loro
plas
t pig
men
ts
Chlorophyll a
(a) Absorption spectra. The three curves show the wavelengths of light best absorbed by three types of chloroplast pigments.
Wavelength of light (nm)
Chlorophyll b
Carotenoids
Figure 10.9
• Chlorophyll a– Is the main photosynthetic pigment
• Chlorophyll b– Is an accessory pigment
C
CH
CH2
CC
CC
C
CNNC
H3C
C
CC
C C
C
C
C
N
CC
C
C N
MgH
H3C
H
C CH2 CH3
H
CH3C
HHCH2
CH2
CH2
H CH3
C O
O
O
O
O
CH3
CH3
CHO
in chlorophyll a
in chlorophyll b
Porphyrin ring:Light-absorbing“head” of moleculenote magnesiumatom at center
Hydrocarbon tail:interacts with hydrophobicregions of proteins insidethylakoid membranes ofchloroplasts: H atoms notshown
Figure 10.10
• When a pigment absorbs light– It goes from a ground state to an excited state,
which is unstable
Excitedstate
Ener
gy o
f ele
ction
Heat
Photon(fluorescence)
Chlorophyllmolecule
GroundstatePhoton
e–
Figure 10.11 A
• A photosystem– Is composed of a reaction center surrounded by a number of
light-harvesting complexes
Primary electionacceptor
Photon
Thylakoid
Light-harvestingcomplexes
Reactioncenter
Photosystem
STROMA
Thyl
akoi
d m
embr
ane
Transferof energy
Specialchlorophyll amolecules
Pigmentmolecules
THYLAKOID SPACE(INTERIOR OF THYLAKOID)Figure 10.12
e–
Fotofosforilasi non siklik
• Elektron yang tereksitasi diganti posisinya oleh elektron asal fotolisis air dan tidak bisa mereduksi pigmen lagi atau di bawa ke P700.
• Cahaya diserap oleh pigmen utama di FS I dan FS II.
• Elektron dari FS digunakan untuk mereduksi NADP
• Menghasilkan ATP, NADPH, dan oksigen
Fotofosforilasi Siklik
• Elektron yang tereksitasi dapat kembali ke P700 melalui rantai transfer elektron
• Hanya melibatkan FS I• Tidak mereduksi NADP• Hanya menghasilkan ATP
• Produces NADPH, ATP, and oxygen
Figure 10.13 Photosystem II(PS II)
Photosystem-I(PS I)
ATP
NADPH
NADP+
ADP
CALVINCYCLE
CO2H2O
O2 [CH2O] (sugar)
LIGHTREACTIONS
Light
Primaryacceptor
Pq
Cytochromecomplex
PC
e
P680
e–
e–
O2
+
H2O2 H+
Light
ATP
Primaryacceptor
Fd
ee–
NADP+
reductase
ElectronTransportchain
Electron transport chain
P700
Light
NADPH
NADP+
+ 2 H+
+ H+
1
5
7
2
3
4
6
8
• A mechanical analogy for the light reactions
Millmakes
ATP
ATP
e–
e–e–
e–
e–
Phot
on
Photosystem II Photosystem I
e–
e–
NADPH
Phot
on
Figure 10.14
• In cyclic electron flow– Only photosystem I is used– Only ATP is produced
Primaryacceptor
Pq
Fd
Cytochromecomplex
Pc
Primaryacceptor
Fd
NADP+
reductaseNADPH
ATPFigure 10.15
Photosystem II Photosystem I
NADP+
• The light reactions and chemiosmosis: the organization of the thylakoid membrane
LIGHTREACTOR
NADP+
ADP
ATP
NADPH
CALVINCYCLE
[CH2O] (sugar)STROMA(Low H+ concentration)
Photosystem II
LIGHTH2O CO2
Cytochromecomplex
O2
H2O O21
1⁄2
2
Photosystem ILight
THYLAKOID SPACE(High H+ concentration)
STROMA(Low H+ concentration)
Thylakoidmembrane
ATPsynthase
PqPc
Fd
NADP+
reductase
NADPH + H+
NADP+ + 2H+
ToCalvincycle
ADP
PATP
3
H+
2 H++2 H+
2 H+
Figure 10.17
Siklus Calvin
• Terjadi di stroma kloroplas• Menggunakan hasil dari reaksi terang (ATP
sebagai energi utama dan NADPH2 sebagai sumber energi pereduksi)
• Memerlukan CO2 • Tidak memerlukan cahaya• Ditemukan oleh Melvin Calvin.• Terdiri dari 4 tahap : karboksilasi, reduksi,
regenerasi, dan sintesis produk.
• The Calvin cycle
(G3P)
Input(Entering one
at a time)CO2
3
Rubisco
Short-livedintermediate
3 P P
3 P P
Ribulose bisphosphate(RuBP)
P
3-Phosphoglycerate
P6 P
6
1,3-Bisphoglycerate6 NADPH
6 NADPH+
6 P
P6
Glyceraldehyde-3-phosphate(G3P)
6 ATP
3 ATP
3 ADP CALVINCYCLE
P5
P1G3P
(a sugar)Output
LightH2O CO2
LIGHTREACTION
ATP
NADPH
NADP+
ADP
[CH2O] (sugar)
CALVINCYCLE
Figure 10.18
O2
6 ADP
Glucose andother organiccompounds
Phase 1: Carbon fixation
Phase 2:Reduction
Phase 3:Regeneration ofthe CO2 acceptor(RuBP)
The Importance of Photosynthesis: A Review
Light reactions:• Are carried out by molecules in the thylakoid membranes• Convert light energy to the chemical energy of ATP and NADPH• Split H2O and release O2 to the atmosphere
Calvin cycle reactions:• Take place in the stroma• Use ATP and NADPH to convert CO2 to the sugar G3P• Return ADP, inorganic phosphate, and
NADP+ to the light reactions
O2
CO2H2O
Light
Light reaction Calvin cycle
NADP+
ADP
ATP
NADPH
+ P 1
RuBP 3-Phosphoglycerate
Amino acidsFatty acids
Starch(storage)
Sucrose (export)
G3P
Photosystem IIElectron transport chain
Photosystem I
Chloroplast
Figure 10.21