Online Karyotyping Activity NAME:
Go to http://www.biology.arizona.edu/ and click on Karyotyping under Human Biology in the left hand column.
During mitosis, the 23 pairs of human chromosomes condense and are visible with a light microscope. A karyotype analysis usually involves 1. __________________ the condensed chromosomes with Giemsa dye. The dye stains regions of chromosomes that are rich in the base pairs
Adenine (A) and Thymine (T) producing a dark band. A common misconception is that 2. ___________
__________________________________________________________________, but in fact the thinnest bands contain over a million base pairs and potentially hundreds of genes. For example, the size of one small band is about equal to the 3. _____________________________________________
____________________________________________________________________________.
4. Diagram and label the identifying features of a chromosome.
5. The analysis of comparing chromosomes involves what three features?
A.
B.
C.
Your task is to determine the genetics behind the following individual’s medical conditions. You will electronically complete the karyotype for each patient and look for abnormalities that could explain the phenotype. Imagine that you are performing the following analyses for real people, and that your conclusions will drastically affect their lives.
Click on Patient Histories
6. Who is Patient A?
7. How were patient A’s chromosomes obtained?
8. What does fetal mean?
9. What is an epithelial cell?
10. What is amniocentesis?

Lab technicians compile karyotypes and then use a specific notation to characterize the karyotype. This notation includes the total number of chromosomes, the sex chromosomes, and any extra or missing autosomal chromosomes. For example, 47, XY, +18 indicates that the patient has 47 chromosomes, is a male, and has an extra autosomal chromosome 18. 46, XX is a female with a normal number of chromosomes. 47, XXY is a patient with an extra sex chromosome.
11. What notation would you use to characterize Patient A's karyotype?
Making a diagnosis
The next step is to either diagnose or rule out a chromosomal abnormality. In a patient with a normal number of chromosomes, each pair will have only two chromosomes. Having an extra or missing chromosome usually renders a fetus unviable. In cases where the fetus makes it to term, there are unique clinical features depending on which chromosome is affected. Listed below are some syndromes caused by an abnormal number of chromosomes.
12. What diagnosis would you give patient A?
Diagnosis Chromosomal Abnormality
Normal # of chromosomes patient's problems are due to something other than an abnormal number of chromosomes.
Klinefelter's Syndrome one or more extra sex chromosomes (i.e., XXY)
Down's Syndrome Trisomy 21, extra chromosome 21
Trisomy 13 Syndrome extra chromosome 13
Click on Patient Histories
13. Who is patient B?
14. Why is he being tested?
15. Where did the chromosomes for his test come from?
16. What notation would you use to characterize Patient B's karyotype?
17. What diagnosis would you give patient B? (use the chart above)
Click on Patient Histories
18. Who is Patient C?
19. What is polydactyly?

20. What is a cleft lip?
21. From where were chromosomes obtained?
22. What notation would you use to characterize Patient C's karyotype?
23. What diagnosis would you give patient C? (use chart above)
Use the following websites as a guide: http://learn.genetics.utah.edu/
AND http://ghr.nlm.nih.gov/condition=trisomy13 .
Fill in the following table for each of the patients you studied.
Disease Name Description of Disease Symptoms Treatments Population
Affected