Biology Exam1 chapter 4

Biology Exam1 chapter 4 - Chapter 4: Organization of the...

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Pg. 74: The Cell Theory Cell Theory: 1. Cells are the basic living units of organization and function in all organisms 2. All cells come from other cells All cells can be traced back to ancient times through DNA. Pg. 74: Cell Organization and Size Homeostasis: appropriate internal environment The organization of all cells is basically similar o Plasma membrane: structurally distinctive surface membrane that surrounds all cells Allows for homeostasis because separated from outside Allows for exchanging of materials o Organelles: internal structures of cells that are specialized to carry out metabolic activities Cell size is limited o Micrometer is most convenient for measuring cells o Why so small? As cell grows larger, surface area ratio gets smaller >> pointless because surface area is used to transport materials in and out so it needs more surface area Microvilli: some cells have these to increase surface area dramatically Cell size and shape are related to function Pg. 76: Methods for Studying Cells Microscope: most important instrument Light microscopes are used to study stained or living cells o Light microscope: LM: tube with glass lenses at each end Compound microscope: contains several lenses o Magnification: ratio of size of image seen with microscope to actual size of object o Resolution/Resolving power: capacity to distinguish fine detail in an image Minimum distance between two points at which they can both be seen separately rather than as a single, blurred point Depends on quality of lenses and wavelength of light Electron microscopes provide a high resolution image that can be greatly magnified o Electron microscope: EM: used to study fine details (ultra structure) Multiplies resolving power by more than 10,000 Electron beam consists of energized electrons Transmission electron microscope: TEM: specimen is embedded into plastic and then cut into slices; electrons pass through specimen Scanning Electron Microscope: SEM: specimen is coated with metal; electrons hits points and secondary electrons are emitted that vary Biologists use biochemical techniques to study cell components o Cell fractionation: technique for purifying different parts of cells so that they can be studied by physical and chemical methods Cells are broken apart and mixture (cell extract) is put into centrifuge Centrifuge breaks into pellet (heavier materials) and supernatant (lighter particles) Pellet can be re-centrifuged to split even more
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Biology Exam1 chapter 4 - Chapter 4: Organization of the...

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