01:119:115 Lecture Notes - Lecture 5: Tupperware, Lipid Bilayer, Ribosomal Rna
19 Jun 2016
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Studying cells: microscopes: used to visualize cells. Magnification: how big you can make the image. Resolution: how clear you can make the image. Contrast: difference in brightness between parts of the sample (use dye) Light microscope: used to see cells a little better. Magnify up to 1,000x, best resolution is 0. 2 m so can"t see organelles, can use stains/dyes, is cheap. Magnify 250,000x, best resolution is -1nm (very clear! Good for tiny things), very expensive, kills the organism (don"t see emergent properties) Scanning em: 3d image, beam of electrons on specimen, can"t see its behavior, specimen coated with a thin layer of gold. Transmission em: specimen embedded in plastic, cut into very thin slices, beam of electrons through a specimen, study internal structure of cells, use heavy metals as a stain for more contrast, cell fractionation by using a centrifuge. Homogenization: fractionate cells into their component parts (heavy stuff ends up at bottom)
