Ex. 8: Negative Staining Flashcards
What is negative staining?
stains background, leaves bacteria transparent. due to ionic repulsion
Why do we used a negatively charged chromophore?
because -ive chromophore unable to penetrate cell due to -ive charge on surface of bacteria
Are negative stains heat fixed? What would this mean for cell size?
No. Do not shrink, accurate measure of cell size
Name advantages of negative staining
visualize bacteria hard to stain, such as Mycobacterium. carried out on bacteria too delicate for heat fixing
Why is negative staining useful for viewing capsules?
capsules lack charges at pH of 7 thus impeding staining. by remaining uncoloured, capsules remain visible against coloured field
What is a capsule?
pronounced gelatinous or slimy layer surrounding some bacterial cells
What other preparation is negative staining used in?
human blood films
