Lab Exam 1 Flashcards
Place one drop of water in the center of the slide, transfer small amount of bacterial inoculum from the culture, spread into the size of a nickel, Air dry, heat fix.
Preparation of bacterial smears from solid medium
Wet mount
Determine how to do a wet mount
Let slide dry, heat fix, apply stain (1 to 2 minutes), gently wash with tapwater, blot slide with bibulous paper
Simple staining Crystal violet 20 to 60 seconds
Place a drop of Negrosin at one end of the slide, place loop full of inoculum in the drop, mix, place slide against the drop at 45° angle and spread, Air dry.
Negative staining
Prepare a slide (Inoculum, water, smear, heat fix). Flood slide with crystal violet. One minute. Wash with tapwater (Still purple). Flood slide with gram’s iodine. One minute. Wash with tapwater. Decolorize with ethyl alcohol (Almost clear). Wash with tapwater. Counterstain with saffranin for 45 seconds. Wash with tapwater. Blot dry.
Gram staining
The bending power of light passing through air from glass slide to objective lens
Retractive index
When one lenses and focus, the other lenses will also have the same focal length, and can be rotated into position without further major adjustment.
Parfocal
Vibratory movement of the cells due to their bombardment by water molecules in the suspension
Brownian movement
Pair of cocci
Diplococcus
Chain of cocci
Streptococcus
Cluster of cocci
Staphylococcus
Packet of four cocci
Tetrad
Packet of eight cocci
Sarcina
Rod shaped, pair
Diplo bacillus
Rod shaped chain
Streptobacillus
Spiral bacteria, curved rods
Vibrios
Spiral, helical and Rigid
Spirilla
Spiral bacteria, helical and flexible
Spirochetes
Two Loopfulls of the cell suspension, spread suspension, allow the smear to air dry, heat fix.
Preparation of bacterial smears from broth medium
Requires the use of at least four chemical reagents that are applied sequentially to heat fixed smear
Differential staining
Imparts it’s color to all cells, Crystal violet
Primary stain
Killing agent, increases the cells affinity for a stain, Used to intensify the color of the primary stain, grams iodine
Mordant, Crystal – Violet – iodine complex CV –I
Protein dehydrating agent and lipid solvent. In gram-negative cells, the alcohol increases the porosity of the cell wall by dissolving the lipids in the outer layer. CV – I complex is washed out. Gram-positive cells retain CV – I complex do you to thicker peptidoglycan. May or may not remove the primary stain from the entire cell or for only certain cell structures.
Decolorizing agent, ethyl alcohol