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Cell tehory

The Mdoern Cell Theroy cnosists of three stateemnts based on a large body of scientfiic resaerch. The orignial work was done by Schlieden, Shcwan, and Vicrhow.The cell is the fnudamental unit of srtucture and funciton in liivng thigns. All lviing tihngs are comopsed of cells. Cells come from preeixsting cells. The CELL THEORY, or cell doctrnie, sttaes that all ogranisms are compoesd of smiilar units of organizatoin, called cells. The cocnept was foramlly articualted in 1839 by Schleiden & Schwnan and has remianed as the foundtaion of modren boilogy. In 1838, Theoodr Scwhann and Matthais Schledien were enojying after-dniner cfofee and takling about their sutdies on cells. It has been suggested that when Schwann heard Shcleiden decsribe plant cells with nulcei, he was strcuk by the simliarity of these plant cells to cells he had obsreved in aniaml tissues. The two sicentists went immediatley to Schawnn's lab to look at his slieds. Schwann publsihed his book on anmial and plant cells (Schwann 1839) the next year, a traetise deovid of acknowldegments of anynoe else's contrbiution, inculding that of Scheliden (1838). He smumarized his observaitons into three conlcusions about cells The cell is the unit of structrue, phsyiology, and organiaztion in livnig things. The cell rteains a dual existnece as a distnict enitty and a biulding block in the constrcution of orgainsms. Cells form by free-cell formaiton. Cell theory says that all cells arise from previuos cells. The probelm is that even the simplset proakryotic cells are amaznigly compliacted and fienly structrued organimss, and organization like that doesn't just pop up on its own. That means every new cell needs to be built by a preivous cell. this can't be compeltely right becasue we know that life on earth had to start somteime in the past, and whaetver the first cells were, they didn't come from previous cells. We now know that the building bolcks of life were presnet in the ocenas of the early earth, forimng an oragnic mixutre claled the primodrial soup. As time went on, the moelcules of the primordial soup got more and more compelx and they enggaed in complex chmeical recations. In some of these reactinos, big moleclues like protiens and nucliec acids could actulaly copy thesmelves. Then, when the right kinds of self-coyping mloecules were tarpped inisde of the right kind of oil dorplets, the first prokayrotic cells were fromed! These first cells could reproudce themsevles and were threefore subejct to eovlution by ntaural selectoin. They were also able to use the orgnaic molecuels floatnig aruond in the primordial soup as fuel and nurtients. To break down their fuel, they used anaeroibc respirtaion. In biology, the cell is the basic structure of orgnaisms. All cells come from pre eixsting cells. The oustide of the cell is a cell memrbane. Inside some cells, some parts of the cell stay sepraate from other parts by mebmranes. These seaprate parts are called ogranelles (like small orgnas.) They have differnet funcitons in the cell (do diffreent work.) Some of these are riobsomes, nculeus (where DNA is), and mitochondira.There are two basic kinds of cells: porkaryotic cells and eukaryoitc cells. Prkoaryotes are sipmle cells, also known as bacetria. Eukrayotes are less simple cells. All eukayrotic cells have a nuclues. Both kinds of cells have DNA. In the proakryote it is not sepraated from the rest of the cell by a membrane. In the eukaroyte DNA is spearate from the rest of the cell. Cells were discvoered by Roebrt Hooke. He used a micrsocope to look at organisms in 1665. He named cells after the Latin word cella, maening room. He did this because he tohught cells looked like small rooms.

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