Autotrophs Essay

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Organisms are often divided into three major groups: producers, consumers and decomposers. Each group plays a critical role in the food chain, and life would not exist in the way it does now without any one of them. Producers are also known as autotrophs or primary producers while consumers are known as heterotrophs or secondary producers. Autotrophs can produce their own food from materials in the environment using light or chemical energy. On the other hand, heterotrophs rely on other organisms, either plants or animals, for their food source since they cannot synthesize their own food. Autotrophs, such as plants, algae and cyanobacteria, use either photosynthesis or chemosynthesis to produce energy. Most well known organisms of these autotrophs
In plants, proteins called photosynthetic reaction centers contain green chlorophyll that absorbs light energy. These proteins are held inside organelles called chloroplasts, which is abundant in leaf cells. In contrast, bacteria house the proteins in the plasma membrane. Chloroplasts are found in the cells of green plants and photosynthetic algae where photosynthesis takes place. Inside the chloroplast are folded structures in disk-shaped arrangement called thylakoids, which enclose chlorophyll in their membrane. Only certain portions of the light spectrum can be absorbed and the photosynthetic action spectrum is dependent on the type of accessory pigment present. Green plants mostly absorb red and blue wavelengths because the action spectrum corresponds to absorption spectrum for chlorophylls and carotenoids. The color of the pigment comes from the wavelengths of light reflected. Plants appear green because they reflect yellow and green wavelengths of light. Photosynthesis involves two series of chemical events, called the light independent that occurs in the stroma and light dependent reactions that occurs in the lumen. They are also known as light and dark reactions this terminology is somewhat ambiguous, because the entire process of photosynthesis is regulated to take place when an organism absorbs visible light. Organized clusters of chlorophyll and beta-carotene in the thylakoid membrane are present to
Light independent reactions do not require light in order to occur however, products of the light dependent reaction such as ATP and NADPH, are required in order for the to function. Within photosystem I, low energy electrons are reenergized and are passed through an electron transport chain where they are used to reduce the electron carrier NADP+ to NADPH. When the chloroplast is receiving a steady supply of photons, NADPH and ATP molecules are rapidly being provided to the metabolic pathways in the stroma. Therefore ATP and NADPH formed during the light dependent reactions are used in stroma to fuel the Calvin cycle reactions. The light independent reactions use specific molecules to temporarily house the energy. These are also called energy carriers and move the energy from the light dependent to the light independent reactions. Once the energy is released, the energy carriers transmit back to the light dependent reaction in order to obtain more

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