Cell Theory
Cell theory- all organisms are made of one or more cells and the products of those cells. An organism may be a single cell, such as a bacterium, or many cells organized to function together as in an animal or plant. In many celled organisms, there may be intercellular material made by the cells. All cells carry on life activities. The life activities of a many celled organism are the combined result of the activities of its individual cells. New cells only arrive from other living cells by the process of cell division.This is where the DNA is kept and RNA is transcribed. RNA is transported out of the nucleus through the nuclear pores. Proteins needed inside the nucleus are transported in through the nuclear pores. The nucleolus is usually visible as a dark spot in the nucleus (note the dark nucleolus in this electron microscope photo of a nucleus), and is the site of ribosome formation. Ribosomes are the sites of protein synthesis, where RNA is translated into protein. Protein synthesis is extremely important to cells, and so large numbers of ribosome's are found throughout cells (often numbering in the hundreds or thousands). Ribosome's exist floating freely in the cytoplasm, and also bound to
This organelle modifies molecules and packages them into small membrane bound sacs called vesicles. These sacs can be targeted at various locations in the cell and even to its exterior. isosmotic solution : a solution having the same osmotic pressure as blood [syn: isotonic solution] Throughout the membrane are proteins stuck inside the membrane. These proteins cross the bilayer and make the holes that let ions and molecules in and out of the cell. (That crossing guard thing again.) Chloroplasts are members of a family of organelles called plastids. In many ways, chloroplasts are quite similar to mitochondria. They have a double membrane, an intricately folded inner membrane, their own genetic material and they are involved in a complex process which involves energy conversion. The difference is, of course, that chloroplasts use energy from the Sun to fix carbon dioxide to synthesise sugars and other food molecules and release oxygen, whereas mitochondria break down food molecules using oxygen, to release energy and carbon dioxide. The process by which chloroplasts fix carbon dioxide using energy from the Sun is called photosynthesis. You can click to find out more about photosynthesis. The plant cell wallThe cell wall is a complex matrix which surrounds a plant cell. It is a rigid structure that helps to support the plant and which protects individual cells. This is important because, when plant cells absorb water by osmosis, they swell up and would burst it it was not for the rigid casing of the cell wall. Although different plants cells have walls of different thicknesses, their basis structure is very much the same. Tough fibres of cellulose are embedded in a highly cross-linked matrix of complex sugars such as pectins and hemicelluloses. The structure of the cell wall makes it very strong and mostly impermeable. The cell vacuole
Some common words found in the essay are:
Chloroplasts Chloroplasts, FACILITATED DIFFUSION, Mitochondria Mitochondria, DIFFUSION Facilitated, ER ER, ER Golgi, HYDROPHOBIC HYDROPHILIC, , Organelles-Nucleus DNA, PLASMA MEMBRANE, cell wall, cell membrane, plant cell, electron microscope, plant cells, endoplasmic reticulum, facilitated diffusion, cells cells, carbon dioxide, cell cell, reticulum er er, fix carbon dioxide, electron microscope photo, cell wall plants, endoplasmic reticulum er,
Approximate Word count = 1715
Approximate Pages = 7 (250 words per page double spaced)
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