Photosynthesis 3
By definition, photosynthesis is the trapping of sunlight energy and its conversion to chemical energy, followed by synthesis of sugar phosphates that become converted to sucrose, cellulose, starch and other end products. In plants, photosynthesis takes place in the chloroplasts. Chloroplasts are formed of two membrane layers, the stroma, and the grana. The two outer membranes surround the stroma, which is the semi-fluid interior of the chloroplast. A membrane runs through the stroma and forms the grana. The grana are stacks of thylakoid disks that hold photosystems. The two stages of photosynthesis happen at two different points in the chloroplast. At the inner membrane system, light is absorbed into the chloroplast and ATP (adenosine triphosphate) is formed. This set of reactions is known as the light-dependent reactions. Light is absorbed by different photosynthetic pigments in the stroma. The two different pigments are chlorophylls and carotenoids. The difference between these two pigments is that chlorophylls are green and carotenoids can be orange, red or yellow. It is these two pigments that give plants their color. In the stroma the second part of photosynthesis, known as the light-independent reactions, is com
pleted. Here, in what is also known as the synthesis stage, sugars, starch, and other organic compounds are combined. Size and shape of the leaf of the plant can either aid or hinder the photosynthesis that goes on in that leaf. The light independent reactions involve three different steps. The first step, which is called photoionization, is the giving up of electrons by the pigments. When light hits pigments of the photosystems an electron and it's energy is given off. While the electron moves around the cell on it's way to the chlorophyll reaction center it gives off energy. Very quickly, the electron's energy matches the wavelength that can react with the chlorophyll a. The photosystem will then take the energy that the electron acquired after being released from the pigment and transfer it to an acceptor molecule. After the electron is given off to the acceptor, the second stage of the light-dependent reactions is started. In this second stage, electrons are transferred and eventually end up forming ATP and NADPH. There are two pathways that can occur during the second stage of photosynthesis, they are the cyclic pathway and the noncyclic pathway. In the cyclic pathway, the electron acceptor acquires the electron from the P700 chlorophyll and sends it through an electron transport system. The P700 chlorophyll is named so because it absorbs only light from the red region of the spectrum whit wavelengths of 700 nanometers. An electron transport system is an organized array of enzymes and coenzymes that transfer electrons in
Some common words found in the essay are:
, ATP NADPH, NADP NADP, Benson Cycle, PGAL PGAL, Acid Metabolism, Calvin-Benson Cycle, electron transport system, transport system, electron transport, energy electron, stomata closed, cyclic pathway, noncyclic pathway, carbon dioxide, carbon fixation, p700 chlorophyll, RuBP NADPH, Calvin Benson, type carbon fixation, calvin-benson cycle, calvin benson cycle, stomata closed day, moves electron transport,
Approximate Word count = 1047
Approximate Pages = 4 (250 words per page double spaced)
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