Human karyotypes for teaching, hints for use.

These images were originally TIFF files, which have been converted to jpeg's. At the Lab of Hygiene the karyotypes are analyzed with proprietary software, but for teaching, it is easier and more useful to make hard-copy prints, mimicking the older professional method of using photographs.

You can print the images directly from your web browser. These prints will come out an appropriate size to use in class, although the browser may insert some printing that will obscure part of the image. Be sure to change the printer set up to landscape orientation.

If you save them as a separate file, and print them from a graphics program, you may need to increase the image size. The original files opened to an image size of about three inches wide and two inches tall, which is too small for use by undergraduates. However, they have been left this way to keep the file size smaller file for transferring over the internet. This is how I have used them so far:

  1. Open the file in Photoshop and increase the image size to about 9.5 inches wide. This will result in a length of about 7 inches (and an increase in file size by a factor of 10).
  2. Make sure the page set-up is adjusted to "landscape".
  3. Print on a laser printer. As increasing the image size produces a very large file, it will print slowly.
  4. Photocopy the laser print on a high-quality photocopy machine. The reduction in quality during photocopying seems to be quite small. Printing on relatively heavy paper will make it easier for students to handle the cut out chromosomes.
  5. Use in class as you might have used other karyotypes. I normally provide each student with a karyotype, a scissors, a layout sheet with spaces for each pair, and some pages with discussion of chromosome morphology containing hints for identifying the various pairs. (We are working on a handout to post on this site. It will not be ready till late spring 1999.) There is abundant opportunity for discussion of chromosome shape, and implications of abnormal numbers as they struggle with the layout. When the student and I agree that we have done the best we can, we compare our result to the key, and tape the chromosomes in place with transparent tape. They then bring the karyotype to the next quiz to turn in, after answering a question or two about it.

The keys for this site were prepared using Photoshop. If you have the appropriate computer facilities with Photoshop, or another image editing program that allows rotation and movement of selections, it would be worth exploring having students do this as well.

If you have used karyotypes in your teaching and have other ways of using them that you would be willing to share, let me know and I will make space on this site for your insights.

These karyotypes are from the Wisconsin State Laboratory of Hygiene. They are intended for use in teaching to help students study human chromosomes. Copyright for these images remains with the State Laboratory of Hygiene, apply to them for permission for any other use than non-profit teaching.

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