Here is your essay on Photosynthesis! [I] Photosynthesis: Photosynthesis is one of the most fundamental biological reactions. The chlorophyll bearing plants trap the free energy of sunlight as photons and transform and store it as chemical potential energy by combining CO 2 and blogger.comted Reading Time: 10 mins 1 day ago · Common module texts and human experiences essay questions of The essay process photosynthesis essay about unity in diversity in india. Mera school essay in urdu for class 3, construction project case study pdf, george orwell essay on tea pdf online courses opinion essay, how to write a thesis in a personal essay: essay about the culture of japan Photosynthesis And Synthesis Essay. Photosynthesis is a biochemical process from light using energy from sunlight and carbon dioxide from the atmosphere as reactants to produce oxygen and organic compounds like carbohydrates (Campbell et al. )
Essay on Photosynthesis - Words | Bartleby
The chlorophyll bearing plants trap the free energy of sunlight as photons and transform and store it as chemical potential energy by combining CO 2 and water. The end products of photosynthesis are carbohydrates with loss of oxygen. These directly or indirectly serve as the source of energy for all living beings, except chemosynthetic bacteria.
Image Courtesy : co2crc. InС. Niel suggested that water is the hydrogen donor in the oxidation-reduction that occurs in photosynthesis, photosynthesis essay. The ratio of oxygen evolved to carbon dioxide consumed is one. The over all reaction of photosynthesis is —. Thus, photosynthesis essay, water is the donor of H 2. Thus, photosynthesis essay this reaction, CO 2 acts as an electron acceptor A and H 2 O as an electron donor D.
The energy contained in the visible light portion between and nm is transmitted in discrete particles called photons. A photon contains one quantum of light energy. Photons with photosynthesis essay wave lengths have higher energy. The quantasomes are thought to be the units which absorb light quanta and contain chlorophyll in association with lipid.
Photosynthesis involves a complex series of reactions, photosynthesis essay, some of which take place only in the presence of light, while others can also be carried out in the dark. InR, photosynthesis essay. Hill British Botanist was the first to provide evidence that the photochemical reactions of plant cells took place in chloroplasts. Arnon showed that in the presence of light, chloroplasts could make ATP from ADP and Pi this is the process called photophosphorylation.
In photosynthesis, the electrons flow from H2O to NADPH. The photochemical reaction takes place in the thylakoid membranes. Robert Hill found that when isolated chloroplasts illuminated, they produced oxygen and acquired reducing properties.
Carbon dioxide was not involved and photosynthesis essay had been split into hydrogen and oxygen. When light strikes the chlorophyll molecule, the energy level of an electron is raised. The electron is then passed through a series of carriers, the last one handing it back to the chlorophyll molecule. In losing an electron the chlorophyll photosynthesis essay positively charged and unstable, but neutrality and stability are restored when the electron is returned, photosynthesis essay.
Thus the electrons emitted from chlorophyll are returned to it unchanged and energy being released as heat and fluorescence.
This cyclic process is known as cyclic photophosphorylation. It is concerned with synthesizing ATP molecules but the source of energy is different. Photosynthesis essay photophosphorylation energy comes from sunlight via chlorophyll.
We have already seen that when light strikes chlorophyll an electron is emitted. Now not all the electrons are returned via the electron carrier system to chlorophyll. Sometimes an electron, together with a hydrogen ion, is taken up by a hydrogen acceptor, nicotinamide adenine dinucleotide phosphate NADPwhich is thus reduced, photosynthesis essay. The reduced NADP i. When NADPH 2 loses its hydrogen, the reduced NADP becomes reoxidised and can be used again.
The chlorophyll molecule which has lost an electron is in an unstable state. The hydroxyl ion donates an electron to chlorophyll and the OH resulting from this forms water and oxygen. By acting as an electron donor the hydroxyl ion restores the stability of the chlorophyll molecule, photosynthesis essay. The oxygen is given off in photosynthesis, photosynthesis essay.
The electron derived from the hydroxyl ion is conveyed from one chlorophyll molecule to another via an electron carrier system. This results in the formation of ATP.
This pathway is non-cyclic phosphorylation, photosynthesis essay. The passage of photosynthesis essay in non-cyclic phosphorylation is complex, involving two distinct molecules or groups of molecules of chlorophyll a.
These are known as photosystems I and II. They are at different energy levels, and under the influence of light the energy photosynthesis essay of an electron can be raised, enabling it to be transferred from one system to the other. In the course photosynthesis essay its journey it passes through electron, carriers with resulting ATP synthesis.
One of the electron carriers is an iron-containing protein called ferredoxin. The various pigments [Chlorophyll a blue-greenchlorophyll b yellow-greenphotosynthesis essay, xanthophyll yellowcarotene orange and phaeophytin grey is the breakdown product of chlorophyll.
It appears that electrons are moved from one pigment to another. Chlorophyll a is the final pigment in the series, receiving electrons from other pigments and handing them on via electron carriers to NADP.
In the Figure 5, photosystem I groups of molecules of chlorophyll a is at a higher energy level than photosystem II. When light strikes a chlorophyll molecule belonging to photosysiem I, an electron is raised to a higher energy state and is taken up by an electron acceptor and then passed to NADP.
Meanwhile the electron which has been lost from photosystcm I is replaced by an electron from photosystem II. This later electron, lost from photosystem II under the influence of light is taken up by an electron acceptor and then passed to photosystem I via the electron carrier system with the production of ATP.
The electron lost from photosystem II is replaced by an electron from the hydroxyl ion derived from the splitting of water, photosynthesis essay. Dark reactions involve the reduction of carbon dioxide to form carbohydrate. This photosynthesis essay an endergonic process requiring energy. The energy is supplied by the hydrolysis of ATP formed in the light reactions and also from NADPH 2 which now carries high energy electrons.
The NADPH 2 also provides the hydrogen for reducing the carbon dioxide. The reduction of CO 2and subsequent synthesis of carbohydrate, takes place in a series of small steps, each controlled by a specific enzyme. The individual steps have been analysed by Melvin Calvin and his associates. The chain of reactions is cyclical and known as the Calvin cycle. In the first step the CO 2 combines with a 5-carbon organic compound called ribulose biphosphate RUBP, photosynthesis essay.
This is carbon dioxide acceptor and fixes the CO 2i. The enzyme needed for this is called RUBP carboxylase. The combination of carbon dioxide with ribulose biphosphate gives an unstable 6-carbon compound which splits immediately into two molecules of a 3-carbon Compound, phosphoglyceric acid PGA. Later the PGA is reduced to form a 3-carbon sugar, phosphoglyceraldehyde PGAL.
The hydrogen for the reduction comes from reduced NADP of light reaction, which also supplies most of the energy, the rest coming from Photosynthesis essay. The 3-carbon sugar is now built up to a 6-carbon sugar which can be converted into starch for storage. Not all the 3-carbon sugar PGAL is converted into 6-carbon sugar.
Some of it majority infact enters a series photosynthesis essay reactions which results in the regeneration of ribulose biphosphate. Its continuous supply is important for the continued photosynthesis essay of CO 2. It represents a storage ofcalories per mole. This energy is provided by a total of 12 NADPH and 18 ATP molecules, photosynthesis essay, representing Kcal.
The starch is not the only end-product of photosynthesis. For amino acids formation, nitrates are required. These are converted to ammonium ions which are used for the formation of glutamine.
Fnm this other amino acids are made by transamination. In transaminat on, photosynthesis essay, the amino group is removed from amino acid and transferred to a carbohydrate derivative which is thereby converted into a new amino acid.
Some plants like cane-type plants such as sugar cane and maize, use another compound, photosynthesis essay, phosphoenol pyruvic acid PEP instead of ribulose biphosphate, as the substrate for carbon dioxide fixation in certain of their cells. The immediate product of CO 2 fixation is not 3-carbon PGA but the 4-carbon compound oxaloacetic acid. Because of this, such plants are called C 4 plants in contrast to those that produce 3-carbon PGA which are photosynthesis essay as C 3 plants.
The oxaloacetic acid of C 4 plants is subsequently converted into malic acid, from which CO 2 is fed into the Calvin cycle to form carbohydrate.
Meanwhile, so long as light is available, the PEP can be resynthesized Hall Hatch and Roger Slack. Some unpigmented plastids like leucoplasts store the essential food materials like protein, photosynthesis essay and starch. Later on these are used during germination of seeds and development. Recent studies show that these plastids, like chromosomes, are transmitted directly to the daughter cells during cell division.
Cytoplasmic inheritance of plastids in Mirabilis is the well-known example. They produce phenotypic effects in Oenothera and other plants. The chloroplast matrix contains dissolved salts and enzymes of photosynthesis. Besides these, photosynthesis essay, like mitochondria, it contains RNA, photosynthesis essay, DNA and ribosomes, and is capable of carrying on protein synthesis. The chloroplast ribosomes are of the same size as ribosomes in prokaryotes, photosynthesis essay.
Chloroplasts are also semi-autonomous like mitochondria. They can grow and divide, and their DNA contains a portion of the genetic information needed for the synthesis of chloroplast proteins. Cells have the capacity to outgrow their chloroplasts and the rate of multiplication of chloroplasts is partly independent of the rate of multiplication photosynthesis essay entire cells.
Brawerman and Chargaff discovered it in Euglena gracilis after photosynthesis essay temperature shock. Cells which were photosynthesis essay to multiply rapidly became irreversibly bleached, whereas cells prevented from dividing regained their normal ability to produce chloroplasts.
They concluded that Euglena contains an autonomously replicating factor which is necessary for chloroplast formation. DNA is found in chloroplasts Stocking and Gifford, Ris and Plaut have also found DNA in the chloroplasts of alga Chlamydomonas.
Photosynthesis - Light Dependent Reactions and the Calvin Cycle
, time: 17:46Conclusion Of Photosynthesis - Words | Cram
Here is your essay on Photosynthesis! [I] Photosynthesis: Photosynthesis is one of the most fundamental biological reactions. The chlorophyll bearing plants trap the free energy of sunlight as photons and transform and store it as chemical potential energy by combining CO 2 and blogger.comted Reading Time: 10 mins Photosynthesis sustains virtually all life on planet Earth providing the oxygen we breathe and the food we eat; it forms the basis of global food chains and meets the majority of humankind's current energy needs through fossilized photosynthetic fuels. The process 1 day ago · Common module texts and human experiences essay questions of The essay process photosynthesis essay about unity in diversity in india. Mera school essay in urdu for class 3, construction project case study pdf, george orwell essay on tea pdf online courses opinion essay, how to write a thesis in a personal essay: essay about the culture of japan
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