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Karyotype
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Under the microscope, after careful preparation and staining, chromosomes from dividing cells can be observed, photographed and arranged in pairs for close examination. This is called a karyotype.
Key concepts:
- It is usual to examine the chromosomes of somatic ("body") cells.
- In humans 46 separate chromosomes can be seen in the karyotype.
- Dividing cells (in humans these are usually white blood cells) are stopped in metaphase of mitosis by the addition of the drug colchicine.
- Cells are swollen with water, fixed with alcohol on a glass slide and stained - often with florescent or other dyes.
- A photograph of the stained chromosomes is taken (through a powerful microscope) and the individual chromosomes cut out and arranged in pairs.
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Science@a Distance
© 2001, Professor John Blamire |
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