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Simple staining quickly assesses bacterial shape and size.  SIMPLE STAINING Simple staining quickly assesses bacterial shape and size. This experiment uses crystal violet to help visualize and understand microbial structures more accurately. PROCEDURE Note: If you are keeping a lab notebook, record the date, time, and experiment title on a fresh page before you begin. […]

Introduction to ScienceExperiment 1 Simple Staining Materials Crystal Violet 2 mL Deionized Water 6 Drops Sterile Saline Nutrient Agar Candle Matches *10% Bleach Solution *Isopropyl Alcohol *Sink or Disposable Plastic Container *Microwave or Boiling Water Bath *Permanent Marker Labware 100 mL Beaker Forceps 2 Sterile Cotton Swabs 1 Pair of Disposable Gloves Resusable Metal Inoculation

PROCEDURE:Gram Staining Experiment Inventory Note: If you are keeping a lab notebook, record the date, time, and experiment title on a fresh page before you begin. 1. Over a sink or disposable plastic container, place several drops of crystal violet onto the smear on one of the “Gram” slides so that the sample is completely

Gram Staining Experiment Inventory Materials 2 “Gram” Slides from Experiment 1 Crystal Violet Deionized Water Gram Iodine Decolorizer Safranin *Sink or Disposable Plastic Container *10% Bleach Solution Labware 1/2 Bibulous Paper Sheet Parafilm® 1 Pair of Disposable Gloves *Lab Notebook (optional) *Scissors Note: You must provide the materials listed in *red. EXPERIMENT 3: GRAM STAINING

Use your sterile inoculating loop to transfer a colony from the culture plate that corresponds with the slide you just prepared, and gently mix the microbes with the nigrosin. 4. Place the clean slide at about a 45° angle next to the nigrosin, and use the slide to gently spread the dye over the specimen

NEGATIVE STAINING Negative staining provides a more detailed assessment of a microbe’s morphology and helps prevent any distortion of the mi- crobe’s ultrastructure by the staining procedure. It also makes the outline of the cells highly visible. Nigrosin and bacterial cells are negatively charged. Therefore, negative staining works because like charges repel each other, preventing

Introduction to ScienceExperiment 2Negative Staining Experiment Inventory Materials 2 “Negative slides” from Experiment 1 Nigrosin Candle Matches *Sink or Disposable Plastic Container *10% Bleach Solution *Isopropyl Alcohol Labware 1 Clean Microscope Slide Reusable Metal Inoculation Loop Parafilm® 1 Pair of Disposable Gloves *Lab Notebook (optional) *Scissors *Timer Note: You must provide the materials listed in

Experiment 3 Post-Lab Questions 1. What color are the Gram-positive bacteria after Gram staining? Gram-negative bacteria? (5 points) Gram-positive bacteria appear as dark purple or blue due to retaining the primary dye (Crystal Violet) in the cell wall. Gram-negative bacteria appear as red or pink due to decolorizing to accept the counterstain (Safranin). 2. What

Experiment 3 Post-Lab Questions 1. What color are the Gram-positive bacteria after Gram staining? Gram-negative bacteria? (5 points) Gram-positive bacteria appear as dark purple or blue due to retaining the primary dye (Crystal Violet) in the cell wall. Gram-negative bacteria appear as red or pink due to decolorizing to accept the counterstain (Safranin). 2. What

Experiment 3 Post-Lab Questions 1. What color are the Gram-positive bacteria after Gram staining? Gram-negative bacteria? (5 points) Gram-positive bacteria appear as dark purple or blue due to retaining the primary dye (Crystal Violet) in the cell wall. Gram-negative bacteria appear as red or pink due to decolorizing to accept the counterstain (Safranin). 2. What