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by kjack1913
Last updated 5 years ago

Cell Biology

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MATERIALSdistilled watervial of HeLa cellsred dyemicroscope slideblue dyepipettestaining jarswooden blockhair dryermicroscopeglovesapronsafety glassesimmersion oilclothes pin or slide holder


Our Questions


What did we do?



Our Equipment

My Prediction

What I think will happen?

We will be able to observe human chromosomes on a microscope slide if we follow directionscarefully.


What happened & Why?

In order to analyze an individual’s chromosomes, or prepare a karyotype, the chromosomes must be easily observed. To make chromosomes more visible, a chemical called colchicine is used to stop cell mitosis in metaphase. It is during this stage that chromosomes are most condensed and visible with the light microscope. Once cells are in metaphase, they are placed in a hypotonic solution causing water to enter the cell and cause it to swell. The cells are then placed in a fixative to maintain this condition. These cells then can be “splatted” onto microscope slides, stained and the chromosomes observed. These chromosomes may be photographed, enlarged, cut out and arranged into a karyotype based on size, centromere, location, and banding patterns.

What are HeLa cells?What cellular structure are you preparing on this slide and why?What is a karyotype and how is it prepared?How is a karyotype used in genetic counseling?www.biologycorner.com/APbiology/cellular/notes_cells1.htmlwww.biology4kids.com/files/cell_main.html

1. Orient a microscope slide vertically at a 45-degree angle.2. Obtain a vial of HeLa cells. With a pipette, gently re-suspend the cells in the tube provided.3. Remove a small sample of cell suspension with a pipette and hold the pipette 6-12 inches above the slide. Allow one drop of cell suspension to “splat” onto the slide about ¾ inch from the upper end and tumble down the slide.4. Carefully apply 8-12 more drops from various heights onto the same region of the slide.5. Gently blow across the slide for 2-3 seconds. The drying will help “spread” the chromosomes.6. Allow the cells to air-dry completely.Stop (Discussion of origin of HeLa cells and their uses)7. Dip the slide into the jar containing stain #1 (red) for one second only. Repeat.8. Drain off stain and dip the slide into the jar containing stain #2 (blue) for one second only. Repeat.NOTE: Caution should be taken to avoid carryover of stains (blot the bottom of the slide on a paper towel before transferring).9. Remove the slide from the stain and thoroughly rinse with distilled water.10. Allow the slide to air dry completely. A stream of warm air or blowing may help speed up the drying process.


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