Презентация по биологии на тему "Грамм оң және грамм теріс бактеряилар"

Practical work # 11.4B

(D) Preparation of permanent preparations

Learning objectives: _______________________________________________________________________________________________________________________________________________________________________________________________________________

Hypothesis: _______________________________________________________________________________________________________________________________________________________________________________________________________________

Safety: Take care using the glassware, if there are any spillages or broken glass, tell the teacher immediately. Do not attempt to pick up broken glass or wipe up spillages yourself.

Wash your hands thouroughly.

Gram Stain method: Preparation of a Bacterial smear

1.       Aseptically sterilize the inoculating loop in a hot flame and transfer bacterial cells from the surface of the agar, to a drop of water on a microscope slide, forming a thin film of cells on the surface of the slide. Once the film has dried, the slide is passed through a flame in a process called heat fixing using a clothespin. Heat fixing the preparation will kill the cells and cause them to stick to the surface of the slide.

2.       Place a clothespin on the end of the slide and place over a tray. Place several drops of crystal violet on the slide.

3.       Allow the stain to react with the cells for 60 seconds.

4.       Tilt the slide and allow the excess stain to drain from the slide.

5.       Rinse the slide by dipping the slide in a large beaker  of  water several times.

6.       Hold the slide level, place several drops of Gram’s iodine solution on the slide. Allow the stain to react with the cells for 60 seconds.

7.       Rinse the slide in water as in step 5.

8.       Decolourize the smear with 95% ethyl alcohol. Tilt the slide and apply the alcohol above the smear, allowing it to run across the surface of the slide. Apply the alcohol drop by drop, repeating until the alcohol runs clear.

9.       Rinse the slide with water as above.

10.    Hold the slide level again. Place several drops of the counterstain, safranin (1%), on the slide.

11.    Allow the stain to react with the cells for 20-30 seconds.

12.    Tilt the slide and allow the excess stain to drain from the slide.

13.    Rinse the slide by dipping the slide in a large beaker  of  water several times.

14.    Blot the slide with paper towels.

15.    Place a coverslip over the specimen and examine the stained cells under a microscope.

Note: Gram-positive cells have a high amount of  peptidoglycan in their cell wall and will stain pink.

Gram-negative cells have a low amount of  peptidoglycan in their cell wall and will stain pink.

Draw and label the images of the microorganisms that you see using the microscope, (remember to include the magnification).

1.       Describe and name the type of microorganisms that were on the petri-dish inoculated with milk.

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2.       Describe and name the type of microorganisms that were on the petri-dish inoculated with soil and water.

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3.       Describe and name the type of microorganisms that were on the petri-dish inoculated from the mouth swab.

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4.       Describe the difference in a gram positive and a gram negative organism.

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5.       Draw a diagram of the microorganisms below.

coccus	bacillus	spirilum

Краткое описание документа:

Microbiology practical GRAM STAINING

Note: Gram-positive cells have a high amount of peptidoglycan in their cell wall and will stain pink.

Gram-negative cells have a low amount of peptidoglycan in their cell wall and will stain pink.

Safety: Take care using the glassware, if there are any spillages or broken glass, tell the teacher immediately. Do not attempt to pick up broken glass or wipe up spillages yourself.

Wash your hands thouroughly.