Lect1-Intro Fistan-2015.pdf

LECTURE 1: ENERGY

An important part of understanding life is understanding how energy is stored and moved from molecule to

molecule

http:\\smtom.lecture.ub.ac.id Password: sm09tom1

e-

high energy photon

Compe-tency

HOW TO STUDY

1. My DictionaryBuy a writing book (50 pages, hard cover), and write every English word that you do not understand in my lectures

2. English PresentationFind a publication related to plant physiology, memorize about 3 paragraphs of it (not too long and not too short), and present it

3. PCL (Propagation-Centered Learning)i. Form Student Discussion Group (SDG) each of 5 members

ii. Follow the procedure of PCL (http://smtom.lecture.ub.ac.id/)

iii. Discuss the video that I will give to you (write every words

from the presentation)

4. Paper Write a paper about Plant Physiology

Max. 3 pages (single space)

Format Title

Name (Student and Supervisor)

Abstract

Introduction

Subject

Conclusion

References

PAPERS

EXAMPLE

THE RATE OF PHOTOSTYNHESIS OF SOYBEAN

Romeo and Juliet

Abstract

1. Introduction

General aspect ( 2 paragraphs) what is it (General description; 3-5 sentences)

what is its importance (3-5 sentences)

2. The Rate of Photosynthesis of Soybean

The description of Photosynthesis (3-5 paragraphs):Function and location in plants

The rate of soybean photosynthesis

Factors influencing the rate of soybean photosynthesis

3. Conclusion

4. References

1. INTRODUCTION

LECTURE LAYOUT

INTRODUCTION

Definition

History Of Plant Physiology

How Plants Work

Syllabus

References

ENERGY1. Definition

2. Energy Of Organisms

3. Law of Conservation of Energy

4. State and Form of Energy

5. Radiant Enegy

6. Electron Energy

7. Free Energy

Definition

Plant physiology is the study of the functions and processes occurring in plants the vital processes occurring in plants how plants work

Plant physiology is the study of plant function encompassing

the dynamic processes of growth

metabolism and

reproduction in living plant (Taiz L and Zeiger E 1991).

Plant physiology is a study of the plant way of life

What is Plant Physiology?

Plant physiology is about 1. how plants use the energy of sun to assimilate carbon, 2. how they convert that carbon to stuff of which they are

made,3. how plants obtain and distribute nutrients and water,4. how they grow and develop,

5. how they respond to their environment,6. how they react to stress,7. how they reproduce

In short, plant physiology is about how plants work

INTRODUCTION

What is Plant Physiology about ?

History of Plant Physiology

1. Jan van Helmontbegan the research of the process in the mid-1600s when he carefully measured the mass of the soil used by a plant and the mass of the plant as it grew.

After noticing that the soil mass changed very little, he hypothesized that the mass of the growing plant must come from the water, the only substance he added to the potted plant.

This was a partially accurate hypothesis - much of the gained mass also comes from carbon dioxide as well as water.

However, this was a signaling point to the idea that the bulk of a plant's biomass comes from the inputs of photosynthesis, not the soil itself.

2. Joseph PriestleyO2

a chemist and minister, discovered that when he isolated a volume of air under an inverted jar, and burned a candle in it, the candle would burn out very quickly, much before it ran out of wax. He further discovered that a mouse could similarly "injure" air. He then showed that the air that had been "injured" by the candle and the mouse could be restored by a plant.

3. Jan Ingenhousz O2 produce d by plants +lighta court physician to the Austrian Empress, repeated Priestley's experiments in 1778, . He discovered that it was the influence of sun and light on the plant that could cause it to rescue a mouse in a matter of hours.

4. Jean Senebier CO2 taken up by plants a French pastor, showed in 1796, that CO2 was the "fixed" or "injured" air and that it was taken up by plants in photosynthesis.

5. Nicolas-Théodore de Saussure CO2 +H2Osoon afterwards, showed that the increase in mass of the plant as it grows could not be due only to uptake of CO2, but also to the incorporation of water. Thus the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined.

Modern scientists built on the foundation of knowledge from those scientists centuries ago and were able to discover many

things.6. Cornelius Van Niel

made key discoveries explaining the chemistry of photosynthesis. By studying purple sulfur bacteria and green bacteria, he was the first scientist to demonstrate that photosynthesis is a light-dependent redox reaction, in which hydrogen reduces carbon dioxide.

7. Robert Hill in 1937 and 1939 performed further experiments to prove that the oxygen developed during the photosynthesis of green plants came from water. He showed that isolated chloroplasts give off oxygen in the presence of unnatural reducing agents like iron oxalate, ferricyanide or benzoquinone after exposure to light.

The Hill reaction is as follows:2 H2O + 2 A + (light, chloroplasts) → 2 AH2 + O2

where A is the electron acceptor. Therefore, in light the electron acceptor is reduced and oxygen is evolved.

8. Samuel Ruben and Martin Camen used radioactive isotopes to determine that the oxygen liberated in photosynthesis came from the water.

9. Melvin Calvin and his partner Benson were able to puzzle out each stage in the dark or light-independent phase of photosynthesis, known as the Calvin Cycle.

10. Rudolph A. Marcus, a Nobel Prize winning scientist, was able to discover the function and significance of the electron transport chain.

How Plants Work• The Shoot System

• Above ground (usually) • Elevates the plant above the

soil • Many functions including: • photosynthesis • reproduction & dispersal • food and water conduction

• The Root System

• Underground (usually) • Anchor the plant in the soil • Absorb water and nutrients • Conduct water and nutrients • Food Storage

At organ level

At cellular level

1. Cell wall - a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.

2. Cell membrane - the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.

3. Cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located.

4. Vacuole - a large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell.

5. Mitochondrion - spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell.

6. Christae - (singular crista) the multiply-folded inner membrane of a cell's mitochondrion that are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated).

7. Nucleus - spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane

8. Nuclear membrane - the membrane that surrounds the nucleus.

9. Nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced.

10. Centrosome - (also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. Unlike the centrosomes in animal cells, plant cell centrosomes do not have centrioles.

11. Ribosome - small organelles composed of RNA-rich cytoplasmicgranules , approximately 60 percent RNA and 40 percent protein , that are sites of protein synthesis. In eukaryotes, ribosomes are made of four strands of RNA. In prokaryotes, they consist of three strands of RNA.

12. Chloroplast - an elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts.

13. Chlorophyll - chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green.

14. Stroma - part of the chloroplasts in plant cells, located within the inner membrane of chloroplasts, between the grana.

15. Thylakoid disk - thylakoid disks are disk-shaped membrane structures in chloroplasts that contain chlorophyll. Chloroplasts are made up of stacks of thylakoid disks; a stack of thylakoid disks is called a granum. Photosynthesis (the production of ATP molecules from sunlight) takes place on thylakoid disks.

16. Granum - (plural grana) A stack of thylakoid disks within the chloroplast is called a granum.

17. Amyloplast - an organelle in some plant cells that stores starch. Amyloplasts are found in starchy plants like tubers and fruits.

18. Golgi body - (also called the golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell.

19. Peroxisomes - Microbodies are a diverse group of organelles that are found in the cytoplasm, roughly spherical and bound by a single membrane. There are several types of microbodies but peroxisomes are the most common.

20. Microfilaments - Microfilaments are solid rods made of globular proteins called actin. These filaments are primarily structural in function and are an important component of the cytoskeleton.

21. Microtubules - These straight, hollow cylinders are found throughout the cytoplasm of all eukaryotic cells (prokaryotes don't have them) and carry out a variety of functions, ranging from transport to structural support.

22. Plasmodesmata - Plasmodesmata are small tubes that connect plant cells to each other, providing living bridges between cells.

23. Rough endoplasmic reticulum - (rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transport materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane).

24. Smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transport materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body and membranes

SYLLABUS

LECTURE TOPICS CONTENTS

1. ENERGYIntroduction

Energy

2. PHOTOSYNTESIS ILight Reaction: Synthesis of NADPH

3. PHOTOSYNTESIS IILight Reaction: Synthesis of ATP

4. PHOTOSYNTESIS III Dark Reaction: C3 Plants

5. PHOTOSYNTESIS IVDark Reaction: C4 & CAM Plants

6. RESPIRATIONGlycolysis, TCA Cycle & Terminal

Oxodation

7. TRANSPORT SYSTEMPhloem and Xylem Transport

References1. Taiz, L. and Zeiger, E., 1991. Plant Physiology. The

Benjamin/Cummings Publishing Co., Inc., Redwood City, California

2. Salisbury, F.B. and C.W. Ross. 1992. Plant Physiology3. Salisbury, F.B. and Ross, C., 1969. Plant Physiology.

Wadsworth Publishing Co. Inc., Belmont, California 4. Bidwell,R.G.S. 1979. Plant Physiology. Mac. Millan.

Publishing, New York5. Devlin, R.M. and F.H. Witham. 1983. Plant Physiology. The

Towa State University Press6. Gardner,F.P.,R.B. Pearce and R.L. Mitchell.1985, Physiology

of crop plants7. Hall.D.O. and K.K. Rao 1981. Photosynthesis, London

ENERGY

How Gravity Works

Every mass attracts every other mass through gravity

The strength of the forces is directly proportional to the product of the masses of two objects

1. DEFINITIONEnergy is the ability to do work

The strength of gravity is proportional the to square of the distances between the objects

F = G*m1*m2/d2

What is Energy?

Tides Primarily caused by the pull of the Moon on

Earth

Sun also causes tides

Can work with or against the Moon’s force

Not exactly 24 hours apart

Causes two tidal bulges

2. Energy Of Organisms

Organisms are divided into two groups based on the principal carbon source (Staniewr et al, 1977). Autotrophic: Organisms use inorganic carbon

(plants) Heterotrophic: Organisms use organic carbon

(animals)

Another division of organisms is based on energy sources Phototrophic (or photosynthetic) Organisms use

the radiant (solar) energy Chemotrophic Organisms use the energy released

during chemical oxidations

Combining these two basic criteria leads to the recognition of four major nutritional categories :1. Photoautotrophs, utilizing light as an energy

source and C02 as the principal source of carbon (e.g. higher plants, algae, cyanobacteria and the purple and green sulphur bacteria).

2. Photoheterotrophs, dependent on light as a source of energy and deriving much of their carbon from organic compounds. This category is represented by a specialized group of photosynthetic bacteria known as non-sulphurpurple bacteria.

3. Chemoautotrophs, deriving energy from the oxidation of inorganic compounds and using C02 as the principal carbon source. This category comprises several groups of specialized bacteria, including the nitrifying bacteria and thiobacilli.

4. Chemoheterotrophs, utilizing organic compounds as both energy and carbon sources (e.g. animals, protozoa, fungi and most bacteria).

CARBON SOURCE

EN

ER

GY

SO

UR

CE

AU

TO

TR

OP

HIC

HE

TE

RO

TR

OP

HIC

PHOTOTROPHIC

CHEMOTROPHIC

3. Law of Conservation of Energy1. Energy can neither be created nor destroyed2. Energy is always changing from one kind to another. 3. The total energy of an object never changes. The

amount of energy in the Universe is constant!!

Potential energy + Kinetic energy = Total energy, Total energy – Kinetic energy = Potential energy and Total energy - Potential energy = Kinetic energy

Conservation of Energy is different from Energy Conservation, the latter being about using energy wisely

4. State and Form of Energy

State of Energy Kinetic Energy Potential Energy

Form of Energy Mass Energy Radiant Energy Chemical Energy Electrical Energy Nuclear Energy Thermal Energy Sound Energy Mechanical Energy Magnetic Energy

Kinetic Energy Kinetic energy exists whenever an object

which has mass is in motion with some velocity. Everything you see moving about has kinetic energy. The kinetic energy of an object in this case is given by the relation:

KE = (1/2)mv2

m = mass of the object V = velocity of the object The greater the mass or velocity of a moving

object, the more kinetic energy it has.

Kinetic Energy• The energy of motion.

• The faster the object moves – the more kinetic energy.

• Kinetic energy depends on both mass and velocity.

KE = ½(mass x velocity2)

• Kg m2/s2 =Newton*meter= Joules

The greater the mass or velocity of a moving object, the more kinetic energy it has.

Potential Energy Potential energy exists whenever an object

which has mass has a position within a force field. The most everyday example of this is the position of objects in the earth's gravitational field. The potential energy of an object in this case is given by the relation:

PE = mghPE = Energy (J = Joules) m = mass (kg) g = gravitational acceleration of the earth

(9.8 m/s2) h = height above earth's surface (m)

Example of Power from Niagara Falls Each kg of water gets kinetic energy of

KE = mgh= 1 kg x 9,8 m/s2 x 58 m = 568 J

Each second, 7.6 million kg of water fall, orP = 7.6 x 106 kg/s x 586 J/kg

= 4.3.109 J/s = 4.3109 W

1 W = 1 J/s

H = 58 m

Flow = 7.6.106 kg/s

Energi Massa

E = mC2 atau E = mc2

C = kecepatan cahaya = 2,997925.108 m.s-1

Jadi 1 g massa mempunyai energi

E = 1 x (3.108)2 g.cm.s-1 = 9,0.1016 erg

= 9,0. 1013 J = 2,1. 1013 cal

5. Radiant Enegy Sun’s mass is 2* 1030 kg. Most of this is hydrogen Sun gets very hot because

of fusion energy release Sun’s heat flow out in all

direction by radiation of light

• Radiant energy also called electromagnetic energy is the movement of photons

Stefan–Boltzmann Law

This law states that the power emitted per unit area of the surface of a black body is directly proportional to the fourth power of its absolute temperature. That is

R=T4

R = radiation flux (W.m-2 = J.m-2.s-1) = emissivity (01) = Stefan-Boltzmann constant (5,67032 x 10-8 W.m-2.K-4)T = absolute temperture (273 + 0C).

Apply Stefan-Boltzmann Law To Sun and Earth Sun

RS = (5.67 x 10-8 W/m2 K4) * (6000 0K)4

= 73,483,200 W/m2

EarthRE = (5.67 x 10-8 W/m2 K4) * (300 0K)4

= 459 W/m2

Sun emits about 160,000 times more radiation per unit area than the Earth because Sun’s temperature is about 20 times higher than Earth’s temperature600/300 = 20

Hanya sebagian kecil radiasi matahari yang sampai pada permukaan bumi.

Apabila bumi berada pada jarak rata-rata darimatahari, pancaran (flux) radiasi yang jatuhtegak lurus pada suatu bidang di luar atmosfiradalah 1,99 0.02 ly. min-1 (ly = Langley) yang disebut konstanta radiasi (Munn, 1966)

Ini setara dengan 1389,02 13,96 J.m-2.s-1 (1 ly. min-1 = 1 cal.cm-2 = 698 W.m-2 atau J.m-2.s-1).

Taksiran konstanta radiasi yang seringdigunakan berkisar diantara 1353 - 1367 J.m-

2.s-1 (Munn, 1966; Driessen & Konijn, 1992; Goudriaan & Van Laar, 1994).

Radiation emitted by a human body

The net power radiated is the difference between the power emitted and the power absorbed:

Pnet = Pemit − Pabsorb.

Applying the Stefan–Boltzmann law,

R = (T4-T04)

A = the total surface area of an adult is about 2 m², = the mid- and far-infrared emissivity of skin and

most clothing is near unity, as it is for most nonmetallic surfaces.

T = skin temperature is about 33°C, but clothing reduces the surface temperature to about 28 °C when the ambient temperature is 20 °C.

T0 = the ambient temperature is about 250C in Malang

Hence, the net radiative heat loss is about R = 1* 5.67×10−8 W m−2 K−4 *2 m2[(273+33)4-

(273+25)4] 99.97 W = 99.97 J.s-1

99.97 x 24 hours x 60 minutes x 60 seconds = 8.64 MJ/day

What is light? Light is an electromagnetic wave

What is the electromagnetic wave? It is electricity and magnetism moving

through the space Light was known to be a wave After producing electromagnetic waves of other

frequencies, it was known to be an electromagnetic wave as well.

LIGHT AS A WAVE Wavelength (l) – the distance between crests (or

troughs) of a wave Frequency (v) – the number of crests (or troughs) that

pass by each second. Speed (c) – the rate at which a crest (or trough) moves

(3.105 km/s). Crest

Trough

l• Maxwell calculated the speed of

propagation of electromagnetic waves and found:

This is the speed of light in a vacuum.

Quantum TheoryLight as particles • Light comes in quanta of energy called photons – little

bullets of energy.• A photon is a quantum or irreducible quantity of

electromagnetic radiation.

• By the 1900's the wave model was accepted by scientist as how light moved.

• Ideas of quantum theory were developed when classical physics (the wave model) could not explain several physical phenomena observed in beginning of the 20th century light until further heating, then it will glow red, yellow then

"white" hot. It also did not explain colors given off by various elements as

they burn

Planck's Theory Energy cannot be absorbed or emitted

unless it is a complete packet. Planck's theory states that atoms can

only absorb or release energy in fixed quantum units

• The amounts of energy an object emits or absorbs are called quantum (quanta plural)

• Related the Frequency of the radiation to the amount of energy.

E = hν = hc/lFrequency (v) = c/lh = 6.6262 x 10-34 J-s (joule-seconds)c = speed of light (3x108 [m/s)

The Electromagnetic Spectrum

Shortest wavelengths(Most energetic photons)

Longest wavelengths(Least energetic photons)

Visible radiation: visible to our eyes (wavelength :0.4x10-6 - 0.7x10-6 m)

Red = 0.65 mm, Orange = 0.60 mm, Yellow = 0.55 mm,Green = 0.50 mm, Blue = 0.45 mm & Violet = 0.40 mm

Cahaya dan PAR• Tanaman dalam proses fotosintesis hanya dapat

memanfaatkan pancaran radiasi matahari yang terletak pada batas panjang gelombang 400 - 700 nm

• Radiasi pada batas panjang gelombang 400 - 700 nm disebut PAR (photosynthetically active radiation) atau cahaya nampak (visible radiation)

Dengan memasukkan harga-hargakonstanta, maka

dimana l dalam satuan nano meter (nm)

Sebagai contoh, kandungan energicahaya merah (l = 680 nm) adalah

1 J (Joule) = 107 erg; 1 c (cal) = 4,2 J; 1 eV = 1,6.10-12 erg

l

JE

1710.878,19

Photo Electric Effect Einstein proposed that light consisted of quantized

energy also, he called these energy quanta photons.

He stated the amount of energy of each photon can be calculated by E = hv (Planck's equation)

Einstein believed that if light strikes the surface of a metal, the photon either has enough quantum energy to remove an electron or it doesn't.

Photons can collide with electrons and thus have particle properties, but in addition they also travel at the speed of light and have wave properties!

Photons are massless, however, they have momentum and react to a gravitational field.

The Compton EffectIn 1924, A. H. Compton performed an experiment where X-rays impinged on matter, and he measured the scattered radiation.

Problem: According to the wave picture of light, the incident X-ray should give up some of its energy to the electron, and emerge with a lower energy (i.e., the amplitude is lower), but should have l2=l1.

M

A

T

T

E

R

Incident X-ray

E1 = hc/l1

l2 > l1

Scattered X-rayE2 = hc / l2

eElectron comes flying out

Louis de Broglie

It was found that the scattered X-ray did not have the same wavelength ?

Summary of Photons

Photons can be treated as “packets of light” which behave as a particle.

To describe interactions of light with matter, one generally has to appeal to the particle (quantum) description of light

A single photon has an energy given by E = hc/l,

where h = Planck’s constant = 6.6x10-34 [J s] and, c = speed of light = 3x108 [m/s]l = wavelength of the light (in [m])

Photons also carry momentum. The momentum is related to the energy by:

p = E/c = h/l

6. Electron Energy

Atoms are not indivisible Made up of protons,

neutrons, and electrons

The nucleus contains protons and neutrons

• Subatomic particles have charge (sometimes)– Protons have positive charge, electrons have negative

charge, neutrons have no charge

Terminology

Elements are defined by atomic number Different AMUs result in different isotopes

12C is “carbon 12”, 14C is “carbon 14” etc Mass of particles

Electron = 0,00055 amu Proton = 1,00728 amu Neutron = 1,00866 amu Positron = 0.00055 amu Deutron = 2,01355 amu

A

XZ

• Atomic Number is how many protons an atom has (Z)

• Atomic Mass Number is how many protons and neutrons an atom has (A)

Niel Bohr pada tahun 1913 menyajikangambaran novel atom yang terdiri darielektron yang mengorbit inti

Elektron dapat mengorbit pada jarakyang dekat dengan atau jauh dari inti, dan tempat orbit ini tertentu

C

Elektron (-)

Proton (+)H

Centripetal force Fc = mv2/r

Centrifugal force = electrical attraction between the proton and the electronFe = kZe2/r2

k = 9.109 N.m2/C2

e = muatan elektron= 1.60219.10-19C

Z = jlh proton dalam intir = jari-2 orbitv = kecepatan elektron

r

v

Fc

Fe

Bohr kemudian mengasumsikan bahwa ada orbit tertentu dimana elektron stabil

Elektron yang jauh dari inti dapat jatuh ke orbit yang mendekati inti karena gaya centripetal diikuti dengankehilangan energi potensial (PE)

Mis. Energi total elektron pada orbit n = En dan pada orbit p = Ep

Kehilangan energi dengan elektron jatuh dari orbit n ke p ad.

En – Ep

Energi elelektron pada orbit tertentu (n) dapat diestimasi dengan persamaanberikut

En = -(kZe2/2)(kZe242m/n2h2)

En = -22k2e4Z2m/n2h2 ……..(9)

= 22/7

k = 9.109 N.m2/C2

e = 1.60219.10-19 C

m = 9.1095.10-31 kg

h = 6.6262.10-34 Js

Untuk atom yang mempunyai nomoratom Z (proton + neutron) = 1, persamaan diatas dapat disederhanakanmenjadi

En = -13,6/n2 eV ……………….(10)

1 J = 6,25.1018 eV

Illustration

Singly ionized helium atom which has lost one of its two electrons. Draw the energy-level diagram for this ion

Reasoning

The singly ionized helium atom will be much like hydrogen atom except that the change on nucleus is +2e, and so Z = 2. From equation, it is found

En = -54,4/n2 eV

Sehingga

E1 = -54.4 eV

E2 = -13,6 eV

E3 = -6,04 eV

E4 = -3,42 eV

7. Free Energy The Gibbs free energy is one of the most important

thermodynamic functions for the characterization of a system

Gibbs free energy is defined in 1876 by Josiah Willard Gibbs to predict whether a process will occur spontaneously at constant temperature and pressure. Gibbs free energy, also indicating how much work is attainable for any given process, is defined as

G = H – TS

where G is the Gibbs free energy, measured in joules H is the enthalpy, measured in joules T is the temperature, measured in kelvinsS is the entropy, measured in joules per kelvin

Enthalpy (H) is a measure of the energy associated with a system, and defined as:

H = U + pVwhereH is the enthalpy of the system (in joules), U is the internal energy of the system (in

joules), p is the pressure at the boundary of the system

and its environment, (in pascals), and V is the volume of the system, (in m3).

Note that the U term is equivalent to the energy required to create the system, and that the pV term is equivalent to the energy which would be required to "make room" for the system if the pressure of the environment remained constant.

Enthalpy is sometimes described as the "heat content" of a system under a given pressure. Such a visualization assumes no energy exchange with the environment other than heat or expansion work. Given such restrictions, it can be shown that: The enthalpy is the total amount of energy

which can the system can emit through heat,

Adding or removing energy through heat is the only way to change the enthalpy, and

The amount of change in enthalpy is equal to the amount of energy added through heat. tightly bound molecules have higher heat energy.

Entropy (S) is a measure of the disorder in a system. Molecules distributed randomly have high

entropy (large S) while ordered molecules have low entropy (small S).

The quantity of G cannot be measured experimentally, but the change of free energy (G) or the maximum amount of energy made available can be evaluated.

G = H − TS A chemical reaction will have a H < 0 if the

heat energy of the reactants is greater than the products.

A reaction will have S < 0 if the reaction results in increased order and S > 0 if the reaction results in increased entropy.

Ice melting in a warm

room is a common

example of "entropy

increasing",

described in 1862 by

Rudolf Clausius as

an increase in the

disaggregation of

the molecules of the

body of

When the concentrations of reactants and products are variable for the following reaction

AB

we can determine G as

where R is the universal gas constant, T is temperature, and [B] & [A] are the initial concentrations of the products and reactants.

We can plot G as a function of [B]/[A] to see how the free energy of the reaction changes as reactants are converted to product ([B]/[A] increases).

][

][ln.'0

A

BTRGG

Process Chemical ReactionGo'

(kcal/mol)

photosynthesis 6CO2 + 6H2O --> glucose + 6O2 +686

hydrolysis of

sucrose

Sucrose + H2O --> glucose +

fructose-7.0

conversion of

ATP to ADP

ATP + H2O --> ADP + phophate -7.3

esterification glucose + phosphate --> glucose

6-phosphate + H2O+3.3

As an example, the chemical reaction of photosynthesis has a standard free energy

Go' = +686 kcal/mol

The reverse reaction has

Go' = -686 kcal/mol

Penentuan G

Jika suatu reaksi berlangsung, mis. zat A berubah menjadi zat B seperti berikut

GB > GA = reaksi bersifat eksergonik apabila (energi dibebaskan )

GB GA = reaksi bersifat endergonik (energi digunakan )

]A[

]B[Keq ba

dc

]B[]A[

]D[]C[Keq

ba

dc

BA

DCRTGG

ln0

A

BRTGG ln0

Standard Kimia fisik :

konsentrasi reaktan & produk = 1 M, dan G & G0

dinyatakan pada pH = 0 Biokimia :

konsentrasi reaktan & produk = 1 M kecuali [H+] = 10-7 M, G’ & G0’ dinyatakan pada pH = 7

Jadi perubahan energi bebas standar berbedaantara biokimia dan kimia fisik untuk reaksiyang melibatkan ion hidrogen

Untuk reaksi yang melibatkan H+ sebagaiproduk

Pada keadaan standar, [A] = [B] = [C] = 1 M dan [H+] = 10-7

M, sehinggaG0’ = G0 + RT ln[H+]x = G0 + x RT ln10-7

Jika x = 1, maka pada 2980 KG0’ = G0 –39,95 kJ atau G0 = G0’ + 39,95 kJ Jadi G0 G0’ sebesar 39,95 kJ/mol H+ yang dibebaskan untuk

rekasi yang melibatkan H+. Ini berarti reaksi akan lebih spontanpada pH = 7

Sebaliknya, reaksi yang melibatkan H+ sebagai reaktan

G0 = G0’ - 39,95 kJ Sehingga reaksi akan lebih spontan pada pH = 0

Ilustrasi 1.

Jika glucose 1-phosphate (G1-P) dikonversi ke G 6-P olehenzim phosphoglucomutase pada 250C dengan [G 1-P) turun dari 0,02 M menjadi 0,001 M bersamaan denganpeningkatan [G 6-P) menjadi 0,019, hitunglah G0

ReasoningKonsentrasi substrat, [G 1-P) = 0,02 danproduk, [G 6-P) = 0,019, sehinggaKeq = 0,019/0,001 = 19G0 = -RT ln Keq = -1363 logKeq

= -1363 log 19 = -1745 cal

Ilustrasi 2.Apabila G0’ dari hidrolisis ATP ke ADP+Pi = -7,3 kcal.mol-

1, hitunglah Keg reaksi tersebut Reasoning

G0’ = -RT ln Keq’-7,3 kcal.mol-1 = -(1,98.103 kcal.0K-1.mol-1)

(29800K)(2,303 log Keq’)Log Keq’= 5,35 ; Keq = 2,2.105

Ilustrasi 3.NAD+ dan NADH ad. btk oksidasi dan reduksi nicotinamide adenine dinucleotide. Harga G0 untuk oksidasi NADH = -21,83 KJ.mol-1

pada 2980K. Hitunglah G0, Keq’ dari reaksi tsb. Hitung juga G dan G’ jika [NADH] = 1,5.10-2, [H+] = 3.10-5, [NAD+] = 4,6.10-3

dan pH2 = 0,01 atm. Do it by yourself if you like

Tugas1. How do plants work to live2. What is the function of cell components3. What is energy ? 4. Where do plants for the first time derive

energy from ? 5. What does it mean by potential energy ?6. How much is the mass energy of 0,5 kg body ?7. How much is the free energy of ATP

hydrolysis at pH = 7, 250C and steady state when the concentration of ATP, ADP dan Pi is 10-5 M, 10-3 M dan 10-7 M (G0’ of ATP = 7700 cal.mol-1) respectively ?