Lab 5 Cell Structure and Functions.doc - Name: Brockington,...

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Name: Brockington, Parrish, ToppingLab 5: Cell Structure and FunctionsIntroductionThe basic unit of life is the cell. In lab IV, concerned with basic organic molecules, youinvestigated some of the non-living components that make up the living cell. In thislaboratory exercises you will investigate the structure of prokaryotic and eukaryoticcells, as well as some of the aspects of cellular functions, including diffusion, osmosis,active transport, etc, and the effects of environmental factors on these mechanisms.The cell theory pioneered by Schleiden and Schwann; the development of themicroscope by Leeuwenhoek; and Virchow's Principle were some of the importantcontributions to our early understanding of cells. Our modern understanding is of coursemuch more complex, due, in part, to the development of the electron microscope, DNAresearch, and the ability of biologists to microdissect cells.Cells are either prokaryotic, meaning they have a nucleoid region containing the geneticmaterial, but no membrane bounded nucleus, or they may be eukaryotic, which aregenerally bigger and more complex than prokaryotes; have membrane boundednucleus and specialized compartments that are technically referred to as organelles.The types and number of organelles varies with the specialty and functions of the cell.All cells have a cell membrane and cytoplasm. The latter has the cellular components –organelles, fluids, sugars, amino acids, salts, etc.In order to stay alive and function, cells must interact with their environment to obtainnutrients, water, ions, etc., and to get rid of wastes and to export materials. This isaccomplished by the processes of diffusion, facilitated diffusion and osmosis, all ofwhich are passive mechanisms. There is also active transport and other cell-assistedmechanisms which require the expenditure of energy in the form of ATP. They includeion "pumps", endocytosis, and exocytosis.Osmosis is the movement of water from an area of higher concentration of water to anarea of lower water concentration across a semi-permeable membrane. It is affected bythe concentration of dissolved solutes in the external and internal environments of thecell. The concentrations of dissolved solutes within or outside of the cells may behypertonic, hypotonic or isotonic relative to one another. A solution that has moresolutes than another one is said to be hypertonic. The solution with the lower soluteconcentration is therefore hypotonic. If both solutions being compared have equalamounts of dissolved solutes then the solutions are isotonic to each other. Water alwaysmoves between the two solutions, more so from hypotonic to hypertonic. Hence therewill be a net gain of water by the side of the membrane that has the hypertonic solution.

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Term
Spring
Professor
Carter-Harris

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