Chapter Chapter 7 - KauHelping – You Can · C6H12 O6 Photosynthesis ... 7.1 Autotrophs are the producers of the biosphere ... Leaf Cross Section 7.2 Photosynthesis occurs in chloroplasts

Chapter Chapter 77Photosynthesis: Using Light to Make Food

Copyright © 2009 Pearson Education, Inc.

PowerPoint Lectures for

Biology: Concepts & Connections, Sixth Edition

Campbell, Reece, Taylor, Simon, and Dickey

Lecture by Richard L. MyersTranslated by Nabih A. Baeshen

Introduction: Plant Power

� Plants use water and atmospheric carbon dioxide to produce a simple sugar and liberate oxygen– Earth’s plants produce 160 billion metric tons of sugar

each year through photosynthesisphotosynthesisphotosynthesisphotosynthesis, a process that converts solar energy to chemical energy

– Sugar is food for humans and for animals that we consume consume

Carbon dioxide ثاني اكسيد الكربون

C6H12O6

Photosynthesis البناء الضوئي

H2OCO2 O2

Water

+ 66

Lightenergy

Oxygen gasغاز ا�كسجين

Glucoseجلوكوز

+ 6

الطاقة الضوئية

AN OVERVIEW OF PHOTOSYNTHESISOF PHOTOSYNTHESIS


7.1 Autotrophs are the producers of the biosphere

� AutotrophsAutotrophsAutotrophsAutotrophs are living things that are able to make their own food without using organic molecules derived from any other living thing– Autotrophs that use the energy

of light to produce organic molecules are called


molecules are called photoautotrophsphotoautotrophsphotoautotrophsphotoautotrophs

– Most plants, algae and other protists, and some prokaryotes are photoautotrophsphotoautotrophsphotoautotrophsphotoautotrophs

Kelp, a large algae الكيلب طحلب كبير

7.1 Autotrophs are the producers of the biosphere

� The ability to photosynthesize is directly related to the structure of chloroplasts– ChloroplastsChloroplastsChloroplastsChloroplasts are organelles consisting of photosynthetic pigments, organelles consisting of photosynthetic pigments, enzymesenzymesenzymesenzymes, and other molecules grouped together in membranes


Micrograph of cyanobacteria

(photosynthetic bacteria)(

7.2 Photosynthesis occurs in chloroplasts in plant cells

� ChloroplastsChloroplastsChloroplastsChloroplasts are the major sites of photosynthesis in green plants– ChlorophyllChlorophyllChlorophyllChlorophyll, an important light absorbing pigment in chloroplasts, is responsible for the green color of responsible for the green color of plants– Chlorophyll Chlorophyll Chlorophyll Chlorophyll plays a central role in converting solar energy to chemical energy


Vein

Mesophyll

Leaf Cross Section


CO2 O2Stoma

Mesophyll Cell

ChloroplastThe location and structureof chloroplasts


� ChloroplastsChloroplastsChloroplastsChloroplasts are concentrated in the cells of the mesophyllmesophyllmesophyllmesophyll, the green tissue in the interior of the leafStomataStomataStomataStomata are tiny pores in the leaf that � StomataStomataStomataStomata are tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit

� Veins Veins Veins Veins in the leaf deliver water absorbed by rootsCopyright © 2009 Pearson Education, Inc.

Chloroplast

Outer and innermembranes

Intermembranespace

Thylakoidspace

GranumStroma ThylakoidSpace


�An envelope of two membranes encloses the stromastromastromastroma, the dense fluid within the chloroplast�A system of interconnected membranous sacs called thylakoidsthylakoidsthylakoidsthylakoids segregates the stroma from another compartment, the thylakoid spacethylakoid spacethylakoid spacethylakoid spaceanother compartment, the thylakoid spacethylakoid spacethylakoid spacethylakoid space

–ThylakoidsThylakoidsThylakoidsThylakoids are concentrated in stacks called granamgranamgranamgranam


7.3 Plants produce O2 gas by splitting water

� Scientists have known for a long time that plants produce O2, but early on they assumed it was extracted from CO2 taken into the plant–Using a heavy isotope of oxygen, 18O,

they showed with tracer experimentsthat O actually comes from H O


that O2 actually comes from H2O

Oxygen bubbles on the leaves of an aquatic plant

6 COO22 + 12 H2O

Experiment 1

C6H12OO66 + 6 H2OO + 6 O2

Not labeled

Experiment 2

6 CO2 + 12 H2OO

Experiment 2

C6H12O6 + 6 H2O + 6 OO22

Labeled

Experiments tracking the oxygen atoms in photosynth esisExperiments tracking the oxygen atoms in photosynth esis

Reactants: 6 CO2 12 H2O

Fates of all the atoms in photosynthesis

Products: C6H12O6 6 H2O 6 O2

7.4 Photosynthesis is a redox process, as is cellular respiration

� Photosynthesis, like respiration, is a redox (oxidation-reduction) process– Water molecules are split apart by

oxidation, which means that they lose oxidation, which means that they lose electrons along with hydrogen ions (H+)

– Then CO2 is reduced to sugar as electrons and hydrogen ions are added to it


6 CO2 + 6 H2O C6H12O6 + 6 O2

Reduction

Oxidation

Photosynthesis (uses light energy)

6 CO2 + 6 H2O + EC6H12O6 + 6 O2

Reduction

Oxidation

Cellular respiration (releases chemical energy)

7.4 Photosynthesis is a redox process, as is cellular respiration

� Recall that Recall that Recall that Recall that cellular respiration cellular respiration cellular respiration cellular respiration uses redox uses redox uses redox uses redox reactions to harvest the chemical energy stored in reactions to harvest the chemical energy stored in reactions to harvest the chemical energy stored in reactions to harvest the chemical energy stored in a glucose moleculea glucose moleculea glucose moleculea glucose molecule– This is accomplished by oxidizing the sugar and reducing O2 to H2Oreducing O2 to H2O– The electrons lose potential as they travel down an energy hill, the electron transport system– In contrast, the food-producing redox reactions of photosynthesis reverse the flow and involve an uphill climb


H2O

NADP+

ADPP

LIGHT REACTIONS

Light

Chloroplast

(in thylakoids)

An overview of the two stages ofphotosynthesis that take place in a chloroplast

H2O

ADPP

LIGHTREACTIONS

NADP+

Lightضوء

Chloroplast ب!ستيدة خضراء

REACTIONS

(in thylakoids)

NADPH

ATP

O2

An overview of the two stages ofphotosynthesis that take place in a chloroplastنظرة شاملة لمرحلتي البناء الضوئي التي تتم في الب!ستيدة الخضراء

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH

� Actually, photosynthesis occurs in twotwotwotwo metabolic stagesFirst stageFirst stageFirst stageFirst stage

– One stage involves the light reactions– In the light reactionslight reactionslight reactionslight reactions, light energy is converted in the thylakoid membranes to chemical energy and O2

– Water is split to provide the O2 as well as electrons



� H+ ions reduce NADP+ to NADPH, which is an electron carrier similar to NADH– NADPH is temporarily stored and then – NADPH is temporarily stored and then

shuttled into the Calvin cycle Calvin cycle Calvin cycle Calvin cycle where it is used to make sugar

– Finally, the light reactions generate ATP



� The second stage is the Calvin cycleCalvin cycleCalvin cycleCalvin cycle, which occurs in the stroma of the chloroplast– It is a cyclic series of reactions that builds

Second stageSecond stageSecond stageSecond stage

– It is a cyclic series of reactions that builds sugar molecules from CO2 and the products of the light reactions– During the Calvin cycleCalvin cycleCalvin cycleCalvin cycle, CO2 is incorporated into organic compounds, a process called carbon fixationcarbon fixationcarbon fixationcarbon fixation



NADHو ATPترتبط مرحلتي البناء الضوئي بـ : نظرة شاملة

� NADPH produced by the light reactions provides the electrons for reducing carbon in the Calvin cycle– ATP from the light reactions provides

chemical energy for the Calvin cycle– The Calvin cycle is often called the

dark (or light-independent) reactionsCopyright © 2009 Pearson Education, Inc.

H2O

ADPP

Lightضوء

Chloroplast ب!ستيدة خضراء

CALVINCYCLEدورة كالفين

CO2

NADP+

LIGHT REACTIONS

تفاع!ت الضوء

NADPH

ATP

O2

دورة كالفين(in stroma)

)في الحشوة(

Sugarسكر

An overview of the twostages of photosynthesis

that take place in a chloroplastنظرة شاملة لمرحلتي

ءالبناء الضوئي التي تتم في الب!ستيدة الخضرا

تفاع!ت الضوء

(in thylakoids))في القريصات(

PHOTOSYNTHESIS REVIEWED AND EXTENDED


7.11 Review: Photosynthesis uses light energy, CO2, and H2O to make food molecules

� The chloroplast, which integrates the two stages of The chloroplast, which integrates the two stages of The chloroplast, which integrates the two stages of The chloroplast, which integrates the two stages of photosynthesis, makes sugar from COphotosynthesis, makes sugar from COphotosynthesis, makes sugar from COphotosynthesis, makes sugar from CO2222

– All but a few microscopic organisms depend on the food-making machinery of photosynthesisthe food-making machinery of photosynthesis

– Plants make more food than they actually need and stockpile it as starch as starch as starch as starch in rootsin rootsin rootsin roots, tuberstuberstuberstubers, and fruits


NADP+

CO2

+

H2O

ADPP

Electrontransport

chains

LightChloroplast

CALVINCYCLE

(in stroma)

Photosystem IIRuBP

3-PGA

Summary of the chemicalprocesses of photosynthesis

NADPH

ATP

chains

ThylakoidMembranes

O2Sugars

Photosystem I

LIGHT REACTIONS CALVIN CYCLE

Stroma

G3P Cellularrespiration

CelluloseStarchOther organiccompounds

PHOTOSYNTHESIS, SOLAR RADIATION,

AND EARTH’S ATMOSPHEREAND EARTH’S ATMOSPHERE


7.13 CONNECTION: Photosynthesis moderates global warming

� The greenhouse effectgreenhouse effectgreenhouse effectgreenhouse effect results from solar energy warming our planet– Gases in the atmosphere (often called

greenhouse gases), including CO2, reflect heat back to Earth, keeping the planet warm and greenhouse gases), including CO2, reflect heat back to Earth, keeping the planet warm and supporting life

– However, as we increase the level of greenhouse gases, Earth’s temperature rises above normal, initiating problems



� Increasing concentrations of greenhouse gases lead to global warmingglobal warmingglobal warmingglobal warming, a slow but steady rise in Earth’s surface temperature– The extraordinary rise in CO2 is mostly due to the

combustion of carbon-based fossil fuelscombustion of carbon-based fossil fuels– The consequences of continued rise will be melting of

polar ice, changing weather patterns, and spread of tropical disease



� Perhaps photosynthesis can mitigate the increase in atmospheric CO2

– However, there is increasing widespread deforestation, which aggravates the global warming problem


Plants growing in a greenhouse

Atmosphere

Sunlight

Some heatenergy escapes

into space

Radiant heattrapped by CO 2trapped by CO 2and other gases

CO2 in the atmosphere and global warming

Diffusion: is a process in which particles spread out evenly in an available space

ھو عملية شيوع الجزيئات بالتساوي في فراغ �نتشارامتاح

Selectively permeability: allow some substances to cross or be transported more easily than others

وذلك بسماحھا بسھولة مرور خاصية النفاذ التفاضليةونقل بعض المواد فض&ً عن غيرھا

Concentration gradient: from high concentration to low concentration

من مناطق التركيز العالي إلى مناطق مدرج التركيزالتركيز المنخفض

Passive transport: is theDiffusion across a cell membrane without

ھو ا>نتشار خ&ل غشاء الخلية بدون ا�نتقال السلبيالحاجة إلى طاقة

المصطلح تعريف المصطلح

The Working Cell الخلية العاملة

Diffusion across a cell membrane without energyActive transport: a mechanism for moving a solute against its concentration gradient it requires the expenditure of energy in the form of ATP.

الخ&يا آلية لتحريك المذاب عكس اتجاه مدرج النقل النشط .ATPالتركيز يحتاج ذلك لبذل الطاقة على ھيئة الـ

Osmosis: the Water movement across membranes in response to solute concentration inside and outside of the cell down the concentration gradient.

ھي يتحرك الماء عبر اLغشية استجابة لتركيز ا+سموزيةمدرج التركيز اسفلالمذاب داخل وخارج الخلية تجاه

Tonicity: is a term that describes the ability of a solution to cause a cell to gain or lose water

مصطلح يصف مقدرة المحلول على إكساب أو فقد التوترالخلية للماء



Osmoregulation: is the ablilty of organisms to maintain water balance within their cells

ھي خاصية لدى بعض الحيوانات ا+سموزيالتنظيم المائي داخل خ&ياھا إتزانھاالحفاظ على

facilitated diffusion: a type of passive transport that does not require energy

طقةنوع من النقل السلبي الذي W يحتاج ا�نتشار الُمَدعم

Exocytosis: is used to export bulky moleculesout of the cell

آلية لتصدير الجزيئات الضخمة خارج الطرد الخلويالخلية

Endocytosis: is used to import substances useful to the livelihood of the cell

آلية لتوريد مواد نافعة لمعيشة الخلية إلى ا�بت5ع الخلويداخل الخلية useful to the livelihood of the cellداخل الخلية

Phagocytosis: engulfment of a particle by wrapping cell membrane around it, forming a vacuole

ھو ابت&ع الجزيئات بتغليفھا الخلوي ا;لتھامأو البلعمةبغشاء الخلية مكونة فجوة

Pinocytosis: the same as phagocytosis except that fluids are taken into small vesicles

إW أن السوائل ھي البلعمةعبارة عن نفس الشرب الخلويالتي تؤخذ في حويص&ت صغيرة

Cells:small units, a chemical factory, housing thousands of chemical reactions

وحدات صغيرة ھي بمثابة مصانع كيميائية تحتضن الخ5يا آWف التفاع&ت الكيميائية

Energy: is the capacity to do work and cause change

ھي القدرة على عمل شغل >حداث تغيير لطاقةا



A metabolic pathway: is a series of chemical reactions that either break down a complex molecule or build up a complex molecule

عبارة عن سلسلة من التفاع&ت الكيميائية المسار ا+يضيوالتي إما تھدم أو تبني جزيء معقد

Energy coupling: it is the use of exergonic processes to drive an endergonic one

استخدام التفاع&ت المحررة للطاقة >مداد إقران الطاقةللطاقة بما تحتاجه من الطاقة المستقبلهالتفاع&ت

ATP( adenosine triphosphate): the energy currency of cells and it is the immediate source of energy that powers most forms of

الطاقة في ” ُعملة“ھو ATP)( ا+دينوسينث5ثي فوسفات ھو مصدر الطاقة الفوري الذي يزود ATP والخلية

source of energy that powers most forms ofمعظم أشكال الشغل الخلوي بالطاقة cellular work

معظم أشكال الشغل الخلوي بالطاقة

Active site: where the enzyme interacts with the enzyme’s substrate

حيث يتفاعل ا>نزيم مع عامل ا>نزيم منطقة نشطةالخاص به

Cofactors: inorganic enzymes helpers ھي مواد غير عضوية مساعدة العوامل المرافقةلeنزيمات

Coenzymes: organic enzymes helpers ھي جزيئات عضوية مساعدة مرافقات ا;نزيماتلeنزيمات

Competitive inhibitors: inhibits enzymes because they compete for the enzyme’s active site and thus block substrates from entering the active site

تقوم بالتثبيط Lنھا تستبق نحو الموقع المثبطات التنافسيةالنشط في ا>نزيم وبالتالي تحجب عامله من دخول ذلك

الموقع



Non competitive inhibitors: bind somewhere else and change the shape of the enzyme so that the substrate will no longer fit the active site

ترتبط ھذه المثبطات بمكان آخر المثبطات غير التنافسيةمغيره شكله ف& يصبح الموقع النشط مناسباً اWنزيممن

اWنزيملعامل

Feedback inhibition: a mechanism where the product of a metabolic pathway can serve as an inhibitor of one enzyme in the pathway

آيضيحيث يعمل أحد نواتج مسار بالتثبيط الرجعي اGليةكمثبط Lحد ا>نزيمات في ذلك المسار

Cellular respiration: an exergonic process ھو عملية تفاعل محرر للطاقة والتي التنفس الخلويCellular respiration: an exergonic process that transfers energy from the bonds in glucose to ATP

ھو عملية تفاعل محرر للطاقة والتي التنفس الخلويتحرر الطاقة المختزنة في روابط جزيء الجلوكوز

ATPوتخزينھا فيA kilocalorie (kcal): the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1oC

ھي كمية الحرارة )كالوريكيلو (الحرارية السعرةكيلوجرام من الماء درجة 1المطلوبة لرفع درجة حرارة

) م°ا (مئوية واحدة Dehydrogenase: the enzyme that removes hydrogen from an organic molecule

ا>نزيم الذي )نزع الھيدروجين انزيم( الديھايدروجينيزيزيل الھيدروجين من الجزيء العضوي

NAD+(nicotinamide adenine dinucleotide): a shuttle for electrons

NAD+ )ناقل :)ا+دنين نيكوتين أميد الثنائية نيوكليتيدة&لكتروناتل

Glycolysis تحلل الجلوكوز The citric acid cycle الستريكدورة حامض



Oxidative phosphorylation المؤكِسدة الفسفرةFermentation: an anaerobic (without oxygen) energy-generating process

دون الحاجة (ھو عملية توليد الطاقة W ھوائيا التخمر) Lوكسجين

lactic acid fermentation: oxidizing of NADH by muscle cells and bacteria

تؤكسد الخ&يا العضلية وبعض تخمر الحامض اللبنيNADH الـأنواع البكتيريا مركب

Yeasts: single-celled fungi that not only can use respiration for energy but can ferment under anaerobic conditions

انھاجانب الىھي فطريات وحيدة الخلية ، لخمائرا>نتاج الطاقة فھي ) ھوائيا(تستطيع القيام بالتنفس الخلوي

ال&ھوائيةقادرة على القيام بعملية التخمر تحت الظروف Autotrophs: living things that are able to ھي كائنات حية قادرة على تصنيع الكائنات ذاتية التغذيةAutotrophs: living things that are able to make their own food without using organic molecules derived from any other living thing

ھي كائنات حية قادرة على تصنيع الكائنات ذاتية التغذيةغذائھا دون استخدام جزيئات عضوية مستمدة من أي كائن

حي آخر

Photoautotrophs: the use of energy of light to produce organic molecules by Autotrophs

استخدم طاقة الضوء >نتاج جزيئات التغذية الضوئيةعضوية بالكائنات ذاتية

Chloroplasts: organelles consisting of photosynthetic pigments, enzymes, and other molecules grouped together in membranes

ھي عضيات تتكون من صبغات الب5ستيدات الخضراءمكونة للضوء وإنزيمات ومركبات أخرى مجموعة مع

بعضھا البعض في أغشية Chlorophyll: an important light absorbing pigment in chloroplasts, is responsible for the green color of plants

الب&ستيداتصبغة ھامة Wمتصاص الضوء في الكلوروفيل افي النبات اWخضرالخضراء وھي المسئولة عن اللون

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Chapter Chapter 7 - KauHelping – You Can · C6H12 O6 Photosynthesis ... 7.1 Autotrophs are the producers of the biosphere ... Leaf Cross Section 7.2 Photosynthesis occurs in chloroplasts