Fotosintesis Overview

7/21/2019 Fotosintesis Overview

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Overview Fotosintesis

Dr. Riris Istighfari Jenie, M.Si., Apt.

[email protected]



Energi dapat diubah dari satu

bentuk ke bentuk lainnyaEnergi bebas

(available for work)

vs.

Panas(not available for work)



Matahari: Sumber energi utama

kehidupan di bumi



• Hampir semua tanaman adalah autotrof fotosintetik,

seperti halnya beberapa bakteria dan protists. – Autotrof menghasilkan senyawa-senyawa organiknya

sendiri melalui fotosintesis.

– Energi cahaya matahari diubah menjadi energi yang

tersimpan dalam bentuk ikatan kimia.

(a) Mosses, ferns, andf lowering plants

(b) Kelp

(c) Euglena (d) Cyanobacteria

Dasar-dasar Fotosintesis



Light Energy Harvested by Plants &

Other Photosynthetic Autotrophs

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2



Food Chain



THE FOOD WEB



WHY ARE PLANTS GREEN?

http://images.google.com/imgres?imgurl=http://www.msu.edu/user/dru/Fieldnotes/2004/May27/Frogs/images/Poison%2520Dart%2520Frog%2520on%2520Banana%2520Leaf.jpg&imgrefurl=http://www.msu.edu/user/dru/Fieldnotes/2004/May27/Frogs/pages/Poison%2520Dart%2520Frog%2520on%2520Banana%2520Leaf.htm&h=450&w=600&sz=29&tbnid=BNbRuUpCul4mcM:&tbnh=99&tbnw=133&hl=en&start=19&prev=/images%3Fq%3Dleaf%26svnum%3D10%26hl%3Den%26lr%3D

http://www.7art-screensavers.com/w-files/raindrops-7art-00003Inst.exe



Electromagnetic Spectrum and

Visible LightGamma

rays X-rays UVInfrared &

Microwaves Radio waves

Visible light

Wavelength (nm)



Different wavelengths of visible light are seen bythe human eye as different colors.


Gamma

raysX-rays UV Infrared

Micro-

waves

Radio

waves

Visible light

Wavelength (nm)



Sunlight minus absorbedwavelengths or colors

equals the apparent color

of an object.

The feathers of male cardinals

are loaded with carotenoid

pigments. These pigments

absorb some wavelengths of

light and reflect others.



Why are plants green?

Transmitted light




Plant Cellshave Green

Chloroplasts

The thylakoid

membrane of the

chloroplast isimpregnated with

photosynthetic

pigments (i.e.,

chlorophylls,

carotenoids).



• Chloroplasts

absorb light

energy andconvert it to

chemical energy

LightReflected

light

Absorbedlight

Transmittedlight

Chloroplast

THE COLOR OF LIGHT SEEN IS THE

COLOR NOT ABSORBED



• Fotosintesis adalah proses dimana

organisme autotrof menggunakan energi

sinar matahari untuk menghasilkan gula dan

oksigen dari karbon dioksida dan air.


Carbondioxide

Water Glucose Oxygengas

PHOTOSYNTHESIS



• The Calvin cycle makessugar from carbon

dioxide – ATP generated by the light

reactions provides the energyfor sugar synthesis

– The NADPH produced by the

light reactions provides the

electrons for the reduction of

carbon dioxide to glucose

Light

Chloroplast

Lightreactions

Calvincycle

NADP

ADP+ P

• The light reactions

convert solarenergy to chemicalenergy – Produce ATP & NADPH




Chloroplasts: Sites of Photosynthesis

• Photosynthesis – Occurs in chloroplasts, organelles in certain

plants

– All green plant parts have chloroplasts and carryout photosynthesis

• The leaves have the most chloroplasts

• The green color comes from chlorophyll in the

chloroplasts• The pigments absorb light energy



• In most plants, photosynthesis occursprimarily in the leaves, in the chloroplasts

• A chloroplast contains:

– stroma, a fluid – grana, stacks of thylakoids

• The thylakoids contain chlorophyll

– Chlorophyll is the green pigment that captureslight for photosynthesis

Photosynthesis occurs in chloroplasts



• The location and structure of chloroplasts

LEAF CROSS SECTIONMESOPHYLL CELL

LEAF

Chloroplast

Mesophyll

CHLOROPLAST Intermembrane space

Outer membrane

Inner membrane

ThylakoidcompartmentThylakoidStroma

Granum

StromaGrana



• Chloroplasts contain several pigments

Chloroplast Pigments

– Chlorophyll a

– Chlorophyll b

– Carotenoids

Figure 7.7



Chlorophyll a & b•Chl a has a methyl

group

•Chl b has a carbonyl

group

Porphyrin ring

delocalized e-

Phytol tail



Different pigments absorb light

differently



Excitedstate

e

Heat

Light

Photon

Light(fluorescence)

Chlorophyll

molecule

Groundstate

2

(a) Absorption of a photon

(b) fluorescence of isolated chlorophyll in solution

Eksitasi klorofil di dalam

sebuah kloroplas

Hilangnya energi karena panas

menyebabkan foton cahaya

menjadi berenergi lebih rendah.

Energi yang lebih rendah berarti

lebih panjang gelombangcahayanya.

Energy = (Planck’s constant) x

(velocity of light)/(wavelength of

light)

Bergeser ke cahaya warnamerah di spektrum cahaya.

e



Cyclic Photophosphorylation• Process for ATP generation associated with

some Photosynthetic Bacteria• Reaction Center => 700 nm



Primaryelectron acceptor

Primaryelectron acceptor

Photons

PHOTOSYSTEM I

PHOTOSYSTEM II

Energy for synthesis of

by chemiosmosis

Noncyclic Photophosphorylation• Photosystem II regains electrons by splitting

water, leaving O2 gas as a by-product



• The O2 liberated by photosynthesis is madefrom the oxygen in water (H+ and e-)

Plants produce O2 gas by splitting H2O



2 H + 1 /2

Water-splittingphotosystem

Reaction-center

chlorophyll

Light

Primaryelectronacceptor

Energyto make



NADPH-producingphotosystem

Light

NADP

1

2

3

How the Light Reactions Generate ATP and NADPH



Water-splittingphotosystem

NADPH-producingphotosystem

ATPmill

• Two types of

photosystems

cooperate in the

light reactions



• Dua fotosistem yang berhubungan

mengumpulkan foton cahaya matahari dan

mentransfer energi tsb ke elektron klorofil.

• Elektron-elektron tereksitasi diteruskan dari

akseptor elektron primer ke rantai transpor

elektron. – Pada akhirnya akan diperoleh ATP dan NADPH

Pada reaksi cahaya, transpor elektron

menghasilkan ATP, NADPH, & O2

K i i kk i t i



• Rantai transpor elektron diatur melalui

fotosistem di membran tilakoid dan

memompa H+ melewati membran tersebut.

– Aliran balik H+ melalui membran dimanfaatkan

oleh ATP sintase untuk membentuk ATP

– Di stroma, ion H+ bergabung NADP+ membentuk

NADPH

Kemiosmosis menggerakkan sintesis

ATP pada reaksi cahaya



• Produksi ATP oleh kemiosmosis dalam

fotosintesis

Thylakoidcompartment(high H+)

Thylakoidmembrane

Stroma(low H+)

Light

Antennamolecules

Light

ELECTRON TRANSPORT

CHAIN

PHOTOSYSTEM II PHOTOSYSTEM I ATP SYNTHASE



• A Photosynthesis Road Map

Chloroplast

Light

Stack of thylakoids ADP

+ P

NADP

Stroma

Lightreactions

Calvincycle

Sugar used for

Cellular respiration

Cellulose

Starch

Other organic compounds



Review: Photosynthesis uses light

energy to make food molecules

Light

Chloroplast

Photosystem IIElectrontransport

chainsPhotosystem I

CALVINCYCLE Stroma

LIGHT REACTIONS CALVIN CYCLE

Cellularrespiration

Cellulose

Starch

Otherorganiccompounds

• A summary of

the chemical

processes ofphotosynthesis

http://www.flickr.com/photos/ghonet/27421952/



It's not that

easy bein'

green… but itis essential for

life on earth!







Fotosintesis Overview

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