fotosintesis

Experiment Photosynthesis

Objective :

      That photosynthesis to produce starch.

      That photosynthesis produces oxygen.

      Proving that in photosynthesis process light and chlorophyll are required.

Devices and Materials

1.       Caladium leaf of white dotted

2.       Cassava leaf

3.       Aluminum foil

4.       Iodine solution

5.       Spiritus lamp

6.       Chemical glass

7.       Tissue paper

8.       Alcohol of 95% or alcohol of 75%

9.       Reaction tube

10.   Water

11.   Dropping pipette

12.   Tripod and gauze

13.   Tweezer

Working Procedures

1.       Pick Caladium leaf of white dotted. Make the picked leaf struct by sunlight.

2.       Then immediately put in that caladium leaf into the boiled water until withered.

3.       Move that leaf into reaction tube that has been filled by alcohol of 95% or alcohol 75% and heat that reaction tube in the boiled water. Heat until that leaf is pale.

4.       Lift the leaf if it looks pale, wash cleanly than spread on tissue paper.

5.       Drop leaf by iodine solution or lugol solution.

6.       Observe what is happening in white do that is dropped by lugol/iodine, compare with undotted part.

LANDASAN TEORI PHOTOSYNTHESIS

Photosynthesis is a biochemical process of formation of food substances or energy that is carried out glucose plants, algae, and some types of bacteria with nutrients, carbon dioxide, and water and needed assistance matahari.Hampir light energy of all living things depend on energy produced in photosynthesis. As a result of photosynthesis becomes very important for life on earth. Photosynthesis is also credited with producing most of the oxygen found in Earth's atmosphere. The organisms that produce energy through photosynthesis (photos meaning light) is called a fototrof. Photosynthesis is one one way in photosynthetic carbon assimilation due to free carbon from CO2 bound (fixed) into sugar as energy storage molecules. Another method adopted is the organism to assimilate carbon through chemosynthesis, which carried by a number of sulfur bacteria.  

Pigments 
  
 
Chloroplast structure:
1. outer membrane
2. inter-membrane space
3. membrane in (1 +2 +3: the envelope)
4. stroma
5. thylakoid lumen (inside of thylakoid)
6. thylakoid membrane
7. granum (a collection of thylakoid)
8. thylakoid (lamella)
9. starch
10. ribosome
11. DNA plastids
12. plastoglobula

The process of photosynthesis can not take place in every cell, but only in cells containing photosynthetic pigments.The cells that do not have photosynthetic pigments are not able to perform the process of photosynthesis. On January Ingenhousz experiment, it is known that light intensity affects the rate of photosynthesis in plants. This may occur because of differences in the energy generated by each spektrumcahaya. In addition to these energy differences, other factors become differentiator is the ability of leaves to absorb a variety of different light spectra. Differencesleaves the ability to absorb various light spectrum caused by difference type of pigments contained padajaringan leaf.
In the leaf mesophyll are composed of spongy tissue and rail networks. In both these networks, there are chloroplast-containing green pigment chlorophyll. These pigments is one of the photosynthetic pigment that plays an important role in absorbing solar energy. 
 photosystem
Photosystem is a unit that is capable of capturing sunlight energy that consists of chlorophyll a, antenna complexes, and electron acceptors. In the chloroplast, there are several kinds of chlorophyll and other pigments, such as chlorophyll a is colored light green, dark green chlorophyll b , and carotene are yellow to orange. Pigments are clustered in the thylakoid membrane and form the pigment that plays an important role in photosynthesis.
Chlorophyll a is in part a reaction center. Chlorophyll is instrumental in delivering high-energy electrons to the primary electron acceptor. These electrons then enter the electron cycle system.  Electrons are released chlorophyll a has a higher energy for gain energy from the light coming from the pigment molecule known as an antenna complex.
Photosystem itself can be divided into two, namely photosystem I and photosystem II. In this photosystem I light energy absorbed by chlorophyll a is sensitive to light with a wavelength of 700 nm so that chlorophyll a is also called P700. Energy obtained P700 complex is transferred from the antenna. In photosystem II, the absorption of light energy by chlorophyll a is sensitive to the wavelength of 680 nm, so-called P680. that oxidized P680 is an oxidising agent which is stronger than the P700. With the potential redox larger, will be enough negative electrons to gain electrons from the molecule-molekulair.
 Photosynthesis
Plants are Autotroph. Autotroph means to synthesize food directly from inorganic compounds. Plants menggunakankarbon dioxide and water to produce sugar and oxygen necessary as food. Energy for these processes comes from photosynthesis.Equation for the production of glucose is:
6H2O + 6CO2 + light → C6H12O6 (glucose) + 6O2

Glucose can be used to form other organic compounds such as cellulose and can also be used as fuel. This takes place through respiration, found in both animals and plants. In general, the reactions that occur in respiration, the opposite of the above. In respiration, sugar (glucose) and other compounds will react with oxygen to produce carbon dioxide, water and chemical energy.
Plants capture light using a pigment called chlorophyll. These pigments give the green color in plants. Chlorophyll is contained in organelles called chloroplasts. chlorophyll absorbs light to be used in photosynthesis. Although all parts of a plant that is green chloroplasts, most of the energy produced in the leaves. In the leaf there is a layer cells called mesophyll containing half a million chloroplasts per square millimeter. The light will pass through the epidermis layer of colorless and transparent, to the mesophyll, the site of most of the photosynthesis process.  The surface of the leaves is usually covered by the cuticle of wax that isanti water to prevent absorption of sunlight or excessive evaporation of water.
 Photosynthesis in algae and bacteria
Algae consists of multicellular algae such as algae to microscopic algae which consists of only one cell. Although they are not as complex as land plants, photosynthesis takes place in the same way. Just because the algae have different types of pigment inkloroplasnya, the wavelengths of light are absorbed more varied. All algae produce oxygen and most are Autotroph. Only a small fraction that are heterotrophic, relying on materials produced by other organisms.
 Process
Until now photosynthesis still continues to be studied because there are a number of stages that can not be explained, despite being very much is known about this vital process. The process of photosynthesis is very complex because it involves all the main branches of natural science, like physics, chemistry, and biology itself.
In plants, the main organ of photosynthesis of leaves of the venue. However, in general, all cells that have kloroplasberpotensi to carry out this reaction. In this is the site of a photosynthetic organelle, precisely in the stroma. The result of photosynthesis (called fotosintat) are usually sent to nearby tissues first.
Basically, a series of reactions of photosynthesis can be divided into two main parts: the light reaction (because they require light) danreaksi dark (do not require light but require carbon dioxide).
Light reaction occurs in Grana (singular: granum), while the dark reaction occurs in the stroma. In the light reaction, occurs konversienergi light into chemical energy and produce oxygen (O2). Meanwhile, in a dark reaction occurs cyclic reaction series which form the basic ingredients of sugar from CO2 and energy (ATP and NADPH). The energy used in the dark reaction is obtained from the light reaction.In the dark reaction process is not needed sunlight. Dark reaction aims to transform a compound containing a carbon atom sugar molecule. Of all the radiation emitted by the sun, only certain wavelengths are utilized plants for photosynthesis, the wavelengths in the range of visible light (380-700 nm) . Visible light consists of red light (610-700 nm), yellow green (510-600 nm), blue (410-500 nm) and violet (<400 nm). Each of the different types of light effect on photosynthesis.  This is related to the nature of the work light catcher pigment in photosynthesis. The pigments present in Grana membranes absorb light having certain wavelengths. different pigments absorb light at different wavelengths . Chloroplasts contain several pigments. For example, chlorophyll a mainly absorbs blue light and red-violet. Chlorophyll b absorbs blue light and reflect light orange and yellow-green. Chlorophyll a direct role in the light reaction, while chlorophyll b is not directly involved in light reaction. The process of absorption of light energy causes the release of high-energy electrons from chlorophyll a which would then be distributed and was captured by electron acceptors. This process is beginning of a long series of reactions of photosynthesis.

  Light reactions

 

Light reactions of photosynthesis in the thylakoid membrane 

Light reaction is a process to produce a reduction ATPdan NADPH2. This reaction requires molekulair and sunlight. The process begins with the capture of photons by the pigment as an antenna.
Light reaction which involves two photosystems work together, namely photosystem I and II. photosystem I (PS I) containing the P700 reaction center, which means that this optimal photosystem absorb light at a wavelength of 700 nm, whereas photosystem II (PS II ) containing the P680 reaction center and optimally absorb light at a wavelength of 680 nm.
The mechanism of the light reaction begins with the stage where the photosystem II absorb sunlight so that chlorophyll in PS II electron excitation and cause cargo to be unstable. To stabilize the back, PS II will take an electron from H2O molecules are nearby. Water molecules will be solved by manganese ions (Mn), which act as enzymes. This will result in the release of H + in thylakoid lumen. By using electrons from water, then PS II would reduce plastokuinon (PQ) form PQH2. Plastokuinon a quinone molecule found on thylakoid membrane lipid bilayer.Plastokuinon would send electrons from PS II to a pump H +-called cytochrome b6-f complex. the overall reaction that occurs in PS II are:
2H2O + 4 photons + 2PQ + 4H → 4H + +-O2 + 2PQH2

Cytochrome b6-f complex functions to carry electrons from PS II to PS I by oxidizing PQH2 and reduce small protein that is very easy to move and contain copper, which is called plastosianin (PC). The incident also led to pump H + from stroma into thylakoid membrane. The reactions that occur in the cytochrome b6-f complex is :
2PQH2 + 4PC (Cu2 +) → 2PQ + 4PC (Cu +) + 4 H + (lumen)

Electrons from the cytochrome b6-f complex will be received by photosystem I. this photosystem absorb light energy from PS II separately, but it contains an integral core complex, which receives electrons from H2O through PS II core complex in advance. As a system that relies on light, PS I functioning plastosianin oxidize reduced and electron transfer to Fe-S protein called soluble feredoksin. the overall reaction in PS I is :
Light + 4PC (Cu +) + 4Fd (Fe 3 +) → 4PC (Cu2 +) + 4Fd (Fe2 +)

Furthermore, electrons from feredoksin used in the final stages of the transport of electrons to reduce NADP + to form NADPH. This reaction is catalyzed by enzymes in the stroma-NADP

+ reductase feredoksin. The reaction is :
4Fd (Fe2 +) + 2NADP + + 2H + → 4Fd (Fe3 +) + 2NADPH

H + ions that have been pumped into the thylakoid membrane will enter into the ATP synthase. ATP synthase will compare the formation of ATP with the transport of electrons and H + across the thylakoid membrane. The entry of H + on the ATP synthase to make ATP synthase working to change the ADP and inorganic phosphate (Pi) to ATP. The overall reaction that occurs in the light reaction is as follows :
Ray + ADP + Pi + NADP + + 2H2O → ATP + NADPH + 3H + + O2
  Reaction dark 

Dark reactions in plants can occur through two channels, ie the Calvin-Benson cycle and the Hatch-Slack cycle. In the Calvin-Benson cycle plants convert ribulose 1.5 bisfosfat compounds to compounds with three carbon atoms of compound 3-phosphogliserat. Hence, plants that run through the dark reaction is called the plant C-3. Belay CO2 as a carbon source in plants is aided by the enzyme rubisco. Plant a dark reaction following the path of Hatch-Slack called the plant C-4 because the compounds formed after fixation of CO2 is oxaloacetic which has four atoms whose role is phosphoenolpyruvate karbon.Enzim carboxilase.

Calvin-Benson Cycle
  
 
Calvin-Benson Cycle
The mechanism of the Calvin-Benson cycle begins with the fixation of CO2 by ribulose diphosphate carboxylase (RuBP) to form 3-fosfogliserat. is an enzyme RuBP alosetrik stimulated by three types of changes resulting from pencahayaankloroplas. First, the reaction of the enzyme is stimulated by increasing the pH. If chloroplasts are light, H + ions transported from the stroma into the thylakoid resulted in increased pH of stroma that stimulate the enzyme carboxylase, is located on the surface outside the thylakoid membrane. Second, this reaction is stimulated by Mg2 +, which enters stroma leaves as H + ions, if given a light chloroplasts. Third, the reaction is stimulated by NADPH, which is produced by photosystem I during the provision of light.
Fixation of CO2 is a dark reaction stimulated by light chloroplasts. Fikasasi CO2 through proseskarboksilasi, reduction, and regeneration. Karboksilasi involves the addition of CO2 and H2O into RuBP to form two molecules of 3-fosfogliserat (3-PGA). Then on the reduction phase, the carboxyl group in 3-PGA is reduced to an aldehyde group in 3-fosforgliseradehida (3-Pgaldehida). this reduction does not occur directly, but the carboxyl group of 3-PGA is first converted into esters type of acid anhydride in 1,3-bifosfogliserat acid (1,3-bisPGA) with the addition of a phosphate group from ATP final. This arises from photophosphorylation ATP and ADP is released when the 1,3-bisPGA formed, which changed back quickly to ATP by photophosphorylation reaction enhancement. Material that is actually reducing NADPH, which contribute 2 electrons. Taken together, the Pi released and re-used to convert ADP into ATP.
In the regeneration phase, which is regenerated RuBP needed to react with additional CO2 that diffuses in konstanke in and through the stomata. At the end of the reaction of Calvin, the third ATP required for each molecule of CO2 is tethered, is used to change the ribulose-5- phosphate to RuBP, then cycle starts again.
Three spin cycle will anchor three molecules of CO2 and the end product is 1,3-Pgaldehida. Some used the chloroplast to form starch, while others were taken out. This system makes a constant amount of total phosphate in the chloroplast, but gave risetriosafosfat in the cytosol. used trioses cytosolic phosphate to form sucrose.
Hatch-Slack Cycle 

  
 
Hatch-Slack Cycle
Based on how to produce glucose, plants can be divided into C3 and C4 plants. C3 plants are plants that originated from subtropical regions. This plant produces processing glukosadengan CO2 through the Calvin cycle, which involves fastening enzimRubisco as CO2. C3 plants requires 3 ATP to produce glucose molecules.  However, this ATP can be used in vain without the production of glucose. This can happen if adafotorespirasi, where the enzyme Rubisco CO2 but do not tie up tie up the O2. C4 plants are plants that are commonly found in tropical areas. These plants involves two enzymes in the processing of CO2 into glucose. Enzymes phosphophenol pyruvat carboxilase (PEPco) is an enzyme that will bind the CO2 from the air and then will be oxaloacetic. oxaloacetic will be converted into malate. will terkarboksilasi malate into pyruvate and CO2. Pyruvate will again be PEPco, while the CO2 will go into the Calvin cycle that took place in the bundle sheath cells and involves the enzyme RuBP. this process is called Hatch Slack cycle, which occurs in mesophyll cells. Throughout this process, used five ATP.
 Determinants of photosynthetic rate
The process of photosynthesis is influenced by several factors, factors that can affect directly such as environmental conditions and factors not directly affect the function of organs such as the disruption of several that are important to the process of photosynthesis. The process of photosynthesis was sensitive to several environmental conditions include the presence of sunlight, temperature environment, the concentration of carbon dioxide (CO2). Environmental factors are known also as the limiting factor and directly affects the rate of photosynthesis.
The limiting factor to prevent the rate of photosynthesis achieve optimum conditions for photosynthesis, although other conditions have improved, this is why the limiting factors that strongly influence the rate of photosynthesis that is by controlling the optimum rate of photosynthesis. In addition, factors such as the translocation of carbohydrates, age leaves, and availability of essential nutrients affect the photosynthesis fungsiorgan thus indirectly affect the rate of photosynthesis.
Here are some key factors that determine the rate of photosynthesis :
1. Light intensity
Maximum photosynthetic rate when a lot of light.
2. Concentrations of carbon dioxide
The more carbon dioxide in the air, the more amount of material used dapt photosynthesis of plants to establish.
3. Temperature
The enzymes that work in the photosynthetic process can only work at optimum temperature. Generally fotosintensis rate increases with temperature until tolerance limit of the enzyme.
4. Water content
Water shortage is causing the stomata to close, blocking the absorption of carbon dioxide, thereby reducing the rate of photosynthesis.
5. Fotosintat levels (of photosynthesis)
If fotosintat such as reduced carbohydrate content, photosynthesis rate will rise. If levels increase or even sampaijenuh fotosintat, the rate of photosynthesis will decrease.
6. Growth phase
Research shows that the rate of photosynthesis is much higher in plants that were germinated than adult plants. This may be due to the plants germinate and require more energy to grow food. 

NO	KEADAAN DAUN	DAUN YANG TIDAK TERTUTUP ALUMUNIUM FOIL	DAUN YANG TERTUTUP ALUMUNIUM FOIL
1.	Sebelum di rebus air panas	Green	brown
2.	Sesudah direbus air panas	Green	brown
3.	Sesudah direbus dalam alcohol	Green	brown
4.	Setelah ditetesi larutan iodine	Biru kehitaman	brown

Pembahasan  

Where do green plants get their organic materials? Green plants are able to produce organic material they need by themselves. Living organism need energy for living. We need food and drink to get energy and materials. We eat rice,corn,vegetables, and bananas.those come from plants. We also eat eggs meat, and butter, and drink milk. Those come from animals.those animals may eat leaves of rice, cassava, or other plants. In other words, animals get energy from the green plants. 

Kesimpulan

In photosynthesis process are water (H2O) and carbon dioxide (CO2). Photosynthesis also needs light, mainly sunlight. Photosynthesis products are glucose and oxygen.

Exercise

1.       Pada percobaan diatas, mengapa daun yang akan diuji direbus terlebih dahulu.(karena untuk mematikan cell-cell daun)

2.       Setelah daun dimasukkan ke dalam alcohol panas, alcohol menjadi warna hijau mmengapa demikian (karena pigment daun)

3.       Pada tabel  diatas, dapat dilihat bahwa kedua  daun yang telah ditetesi larutan iodine warnanya berbeda ( karena yang satu permukaan daunnya tertutupi oleh alumunium foil sehingga tidak bias mengankap cahaya dengan sempurna kalau yang tidak tertutupi oleh alumunium foil bias menangkap cahaya dengan sempurna)

4.       Faktor abiotik apa saja yang dapat dilihat pengaruhnya dalam percobaan ini

      Tempat

      Waktu s