Exam I SG Set 2 QA-revised

Exam I SG Set 2 QA-revised - Study Question Sets for Exam 1...

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Study Question Sets for Exam 1   Study Question Set 2 -- EM, Tissue Preparation, and Staining 1. Describe the steps involved in preparing a rat liver for staining before examination with a  standard light microscope. Fixation, Dehydration, Embedding, and Sectioning.  First, the rat liver cells are treated with  a fixative to immobilize, kill, and preserve them.  The fixation makes the liver cells  permeable to staining reagents and cross-links their macromolecules so that they stay in  place.  The current fixative procedure uses Formaldehyde and Glutaraldehyde, which form  covalent bonds with the free amino groups of proteins of the large molecules in liver cells,  and so link them together forming methylene bridges.  After fixation, we wash the liver  tissues through series of solutions of decreasing polarity to dehydrate their proteins.  Then  the dehydrated liver tissues are placed in liquid embedding medium (waxes or plastic  resins), which permeate and surround these tissues.  They can then be hardened and are  readily sectioned by the microtome.  Once the liver tissues have been cut into very thin  slides, they are ready for staining before examination with a standard light microscope. 2. Describe how glutaraldehyde functions as a fixative.  Aldehyde fixatives form methylene bridges between amino groups in side chains of  proteins; aldehyde groups of glutaraldehyde are enabled to cross-link various types of  molecules, forming covalent bonds between them.  Such fixatives, stabilize, and lock 
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This note was uploaded on 04/13/2009 for the course BIOL 3622 taught by Professor Ms during the Fall '05 term at UMSL.

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Exam I SG Set 2 QA-revised - Study Question Sets for Exam 1...

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