photosynthesis 2014

8/10/2019 Photosynthesis 2014

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Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

BAGIAN 2

FOTOSINTESIS:Penggunaan sinar untukpembentukan makanan

SUGENG SETYO UTOMOSMA NEGERI 2 LUMAJANG


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Light is central to the life of a plant

Photosynthesis is the most important chemical processon Earth

It provides food for

virtually all organisms Plant cells convert light

into chemical signalsthat affect a plantslife cycle

2.1 Life in the Sun


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Light can influencethe architecture of a

plant

Too much sunlightcandamage a plant

Chloroplasts andcarotenoidshelp to preventsuch damage


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Photosynthesis is the process by which autotrophic

organisms use light energy to make sugar andoxygen gas from carbon dioxide and water

AN OVERVIEW OF PHOTOSYNTHESIS

Carbondioxide Water Glucose

OxygengasPHOTOSYNTHESIS

Plants, some protists, and some bacteria are

photosynthetic autotrophs.


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On land, plants such as oak trees and cacti are thepredominant producers

Figure 2.1A Figure 2.1B


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In aquatic environments, algae and photosyntheticbacteria are the main food producers

Figure 2.1 C Figure 2.1 D Figure 2.1 E


7/30Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

In most plants, photosynthesis occurs primarilyin 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

2.2 Photosynthesis occurs in chloroplasts



The location and structure of chloroplasts

Figure 2.2

LEAF CROSS SECTION MESOPHYLL CELL

LEAF

Chloroplast

Mesophyll

CHLOROPLAST Intermembrane space

Outermembrane

Innermembrane

ThylakoidcompartmentThylakoid

Stroma

Granum

StromaGrana



Figure 2.2 A

Figure 2.2 B

Experiment 1

Experiment 2

Notlabeled

Labeled

Reactants:

Products:



Water molecules are split apart and electronsand H+ions are removed, leaving O2gas

These electrons and H+ions are transferred toCO2, producing sugar

2.3 Photosynthesis is a redox process, as is cellularrespiration

Figure 2.3 A

Figure 2.3 B

Reduction

Oxidation

Oxidation

Reduction


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12/30Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 2.4

Light

Chloroplast

LIGHTREACTIONS

(in grana)

CALVINCYCLE

(in stroma)

H2O

O2

CO2

NADP+

ADP+ P

Sugar

ATP

NADPH



2.5 Visible radiation drives the light reactions


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Copyright 2003 Pearson Education, Inc. publishing as Benjamin CummingsFigure 2.5

Light

Chloroplast

Reflected

light

Absorbed

light

Transmittedlight


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Fluorescence of isolated chlorophyll in solution

Figure 2.5 A

Heat

Photon

(fluorescence)

Photon

Chlorophyll

molecule


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Figure 2.5 C

Primary

electron acceptor

Photon Reaction centerPHOTOSYSTEM

Pigment

molecules

of antenna


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The electron transport chains are arranged withthe photosystems in the thylakoid membranesand pump H+through that membrane

The flow of H+back through the membrane isharnessed by ATP synthase to make ATP

In the stroma, the H+ions combine with NADP+

to form NADPH

2.6 Chemiosmosis powers ATP synthesis in thelight reactions


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Photosystem II regains electrons by splittingwater, leaving O2gas as a by-product

Figure 2.6

Primaryelectron acceptor

Primaryelectron acceptor

Photons

PHOTOSYSTEM I

PHOTOSYSTEM II

Energy forsynthesis of

by chemiosmosis

h d i f b h i i i


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The production of ATP by chemiosmosis inphotosynthesis

Figure 2.6A

Thylakoidcompartment(high H+)

Thylakoidmembrane

Stroma(low H+)

Light

Antennamolecules

Light

ELECTRON TRANSPORT

CHAIN

PHOTOSYSTEM II PHOTOSYSTEM I ATP SYNTHASE


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The Calvin cycle occurs inthe chloroplasts stroma

This is where carbonfixation takes place andsugar is manufactured

2.7 ATP and NADPH power sugar synthesis in theCalvin cycle

CALVIN CYCLE: CONVERTING CO2TO SUGARS

INPUT

Figure 7.10AOUTPUT:

CALVIN

CYCLE


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The Calvin cycle constructs G3P using

carbon from atmospheric CO2

electrons and H+from NADPH

energy from ATP

Energy-rich sugar is then converted intoglucose


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Many plants make more sugar than they need

The excess is stored in roots, tuber, and fruits

These are a major source of food for animals


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Most plants are C3plants, which take CO2directly from the air and use it in the Calvincycle

In these types of plants, stomata on the leafsurface close when the weather is hot

This causes a drop in CO2and an increase in

O2in the leaf

Photorespiration may then occur

2.8 C4and CAM plants have special adaptationsthat save water


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Photorespiration in a C3plant

CALVIN

CYCLE

2-C compound

Figure 2.8C


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Some plants have special adaptationsthat enable them to save water

CALVIN

CYCLE

4-C compound

Special cells in C4plantscorn andsugarcaneincorporateCO2into a four-carbon

molecule

This molecule can thendonate CO2to the

Calvin cycle

3-C sugarFigure 2.8A


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The CAM plantspineapples, most

cacti, and succulentsemploy a differentmechanism

CALVIN

CYCLE

4-C compound

Figure 2.8B

They open theirstomata at night andmake a four-carboncompound

It is used as a CO2source by the samecell during the day

3-C sugar

Night

Day

PHOTOSYNTHESIS SOLAR RADIATION AND


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Due to the increased burning of fossil fuels,atmospheric CO2is increasing

CO2warms Earths surface by trapping heat inthe atmosphere

This is called the greenhouse effect

2.9 Human activity is causing global warming;

photosynthesis moderates it

PHOTOSYNTHESIS, SOLAR RADIATION, ANDEARTHS ATMOSPHERE

Unfortunately, deforestation may cause a

decline in global photosynthesis

Because photosynthesis removes CO2from theatmosphere, it moderates the greenhouse effect


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Figure 2.9

Sunlight

ATMOSPHERE

Radiant heat

trapped by CO2

and other gases

2 buah Kontrol


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2 buah Kontrol

Kontrol suhu tinggi (air panas)

Kontrol suhu rendah (es)

Kontrol pH asam

Kontrol pH basa

Kontrol CO2 tinggi (NaHCO3)

Kontrol i.c. rendah (teduh)

Kontrol i.c. dg. mika kuning

Kontrol i.c. dg. mika hijau

Kontrol i.c. dg. mika merah

Kontrol kecerahan air

photosynthesis 2014

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