Chapter 4 - BSC 1010 Dr. Presley Chapter 4 THE CELL Review...

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BSC 1010 Dr. Presley Chapter 4 THE CELL Review from evolution of cells and cellular basis of life in Chapter 1(notes p.2-3,4) The Cell Theory -- from 1860’s 1. All living things are made of one or more cells and substances produced by cells. *** Cell is the unit of structure 2. The cell can perform all activities needed for its life. These activities include processes, types of molecules and structures in common *** Cell is the unit of function 3. Today, new cells arise (reproduce) only from pre-existing cells. *** Cell is unit for continuity of life Contributers to the cell theoroy: Robert Hooke -- used term "cell" to refer to unit of life (1665), looking a cork Leeuwenhoek -- microscope design to see sperm (1660’s) Schleiden & Schwann -- studied plants and animals respectively (1850’s) - each organism made of cells with different functions, Points #1, 2 Virchow -- “Father of Pathology” – (1858) recognized disease was due to malfunctioning cells, not as current superstition would have it as the result of punishment for an evil thought or action - Cell theory points #2, 3 Pasteur--disproved spontaneous generation of life (1857) - review Fig. 3.23 on p. 58 CELL SIZE *****Study Fig. 4.3 on page 63 Most cells are small (1 - 100 um) Because cell surface (cell membrane) must be able to get supplies into and out of the cell in order to meet the needs of the cell's internal volume Most materials move by the slow process of diffusion Metabolically active cells tend to be the smallest cells Therefore need a large surface area-to-volume ratio REMEMBER: surface area increases as square of radius volume increases as cube of radius therefore, as cell size increases the demands of its internal volume strains the cell surface's ability to supply these needs. Range of cell size is limited by metabolic requirements More active cells are smaller in size(maintain large surface area-to-volume ratio) mycoplasma (0.1-1.0 m), bacteria(1-10 m), eukaryotes(10-100: m) in diameter Shape influences surface area-to-volume ratio: Sphere has largest surface area-to-volume ratio Given the identical volume as this spherical shape, note that these shapes have an even larger surface area : - flattened cells, thread-like cells, cells with irregular surfaces TECHNOLOGY FOR STUDY OF CELLS Microscopy - properties of magnification and resolving power Study Fig 4.2, p. 63 1. Light microscope (LM) (0.2 m - 1,100 m) = 1,000 x human vision *glass lenses and visible provide resolution - Bright-field (metric review in Appendix after page 1121) - Dark-field - Phase contrast - Fluorescence 2. Electron microscope (EM) (100 m - 0.1 nm) = 400,000 x human vision **magnets used to focus electron beam, **view specimen on fluorescent screen or photographic film ** can view only dead cells - scanning electron microscope (SEM) - study surface features - transmission electron microscope(TEM) - study internal ultrastructure See Figure 4.4 on page 64 for images from representative microscopes Thin sectioning
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Chapter 4 - BSC 1010 Dr. Presley Chapter 4 THE CELL Review...

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