Cell lec 1 - Introduction to Cells Cells are small and they...

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Unformatted text preview: Introduction to Cells Cells are small and they can not be seen by naked eyes. The simplest forms of life are solitary cells. Higher organisms, such as ourselves, are communities of cells derived by growth and division from single founder cell. All living creatures are made of one or more cells---- small membrane-bound units filled with a concentrated aqueous solution of chemicals and endowed with extraordinary ability to create copies of themselves by growing and dividing in two. NERVE CELL PARAMECIUM PLANT STEM BDELLOVIBRIO WHITE BLOOD CELL Cells come in a variety of shapes and sizes Introduction to Cells Conts Cell theory states : all organisms are composed of cells, and all living cells are similar to one another in structure and function. Cell functions : maintain a selective barrier that separates the cells internal contents from the extra cellular environment, inherit and transmit genetic material containing encoded instructions used for directing the synthesis of most of the cells components, carry out catalyzed chemical reactions utilized for the synthesis and breakdown of organic molecules--- metabolism , and manifest several types of motility that result in locomotion of the cell as a whole as well as movement of individual components within the cell. Introduction to Cells Conts Each of the four functions listed above is associated with a particular set of morphologically specialized structures, termed organelles, which exist inside cells. Cells can be divided into two groups: Prokaryotes and Eukaryotes 1) Prokaryotes: Prokaryotes are cells without a nucleus . They have genetic materials but are not enclosed within a membrane. These include bacteria and cyanophytes . Streptococcus pyogenes , the bacterium that causes strep throat, is an example of prokaryotes. Their genetic material is a single circular DNA and is contained in the cytoplasm, since there is no nucleus. Recombination happens through transfers of plasmids (short circles of DNA that pass from one bacterium to another). Prokaryotes do not engulf solids nor do they have centrioles or asters. Prokaryotes have a cell wall made up of peptidoglycan. Bacteria come in different shape and sizes Introduction to Cells Conts 2 ) Eukaryotes: are cells with a nucleus , this is where the genetic material is surrounded by a membrane much like the cells membrane. Eukaryotic cells are found in humans and other multicellular organisms (plants and animals )also algae, protazoa. They have both cellular membrane and nuclear membrane, also the genetic material forms multiple chromosomes, that is linear and complexed with proteins that help it 'pack' and is involved in regulation. The fine structure of a cell can be seen in a transmission electron microscope In all living cells, genetic information flows from DNA to RNA (transcription) and from RNA to protein (translation). All living organisms are constructed from cells.All living organisms are constructed from cells....
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Cell lec 1 - Introduction to Cells Cells are small and they...

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