Monday, October 18, 2010

Karyotypes!! Say what!

Karyotype practice and vocabulary

The link above will take you to the second website we visited in class today.  There you can find practice terms and revisit how to make and read a karyotype.

http://www.biotechnologyonline.gov.au/popups/img_karyotype.html

The karyotype above is a normal male.  A technician preparing a karyotype would first arrange the chromosomes by length from longest to shortest.  Then they would match up pairs using banding patterns and centromere placement.

Just think of the way you would match up your socks when folding laundry.  You wouldn't pair the ankle sock with a tube sock.  Nor would you match a pink ankle sock with a white one.  Socks are matched by length and pattern just like chromosomes are matched by length and banding patterns.

Once the karyotype is arranged, then we make sure all the chromosome are normal:
   1. Correct length
   2. Correct banding pattern
   3. Correct # of chromosomes in each pair (none missing and no extra)
  
If any of these characteristics aren't met, then they seek to diagnose the disorder.

For example, above is a karyotype from a human breast cancer cell.  In a normal cell, there are 46 total chromosomes.  As you can see, the cell division process has been altered and the chromosomes are duplicating without any checks and balances.

In the above karyotype, this female is missing a whole piece of her chromosome.  So even though there are 46 chromosomes present, there is still a disorder because information is missing.

This patient has monosomy 7 because there is only 1 chromosome at pair 7.

Basically it boils down to Goldilocks again!  Too much information = problem.  Too little information = problem.

When meiosis goes wrong, the zygote's chromosomal make-up will suffer!

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