Karyotyping Activity
Name ________________________
Date ____________ Period ______
Many genetic disorders are caused by a change in a certain allele. These disorders can be passed from
parent to child and continue down through the generations of a family. Other disorders are caused by a change
to a particular chromosome. These disorders are not inherited; they are a result of a mistake during meiosis
when the gametes are produced.
Go to the following website:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
Read the information contained on the webpage and answer the questions that follow.
1. a) A karyotype is a picture (“photomicrograph”) of chromosomes arranged in pairs. Would a medical
technologist use chromosomes taken from a cell in interphase or a cell in mitosis? Explain.
b) What is used to stain the chromosomes for a karyotype?
c) Why are some bands on the chromosomes darker than others?
d) Approximately how many genes are located in each dark band?
2. Describe 3 features that are compared when scientists try to pair chromosomes with their match:
a)
b)
c)
3. Summarize the purpose of this activity.
4. Click on the “Patient Histories” button at the bottom of the page. Summarize the patient histories of each.
Patient
Patient History
A
B
C
Click on “Complete Patient A’s Karyotype”.
 Using the features you described in question #3, place each chromosome with its match.
 Place the chromosome with its match by clicking on the number of the chromosome that it most
resembles (only choose from the numbers in blue).
 When you have successfully finished the karyotype, answer question #5 on the next page.
Read the section titled “Interpreting the karyotype”.
5. Write the notation used to characterize Patient A’s fetal karyotype. Scroll to the bottom of the page to
review the completed karyotype.
 The first blank should be the total number of chromosomes for this patient’s fetus. (Ex: 46, 47, etc.)
 The second blank should be the gender of the fetus (Ex: XY)
 The third blank should be the number of chromosome pair that is abnormal with a “+” or “-“ in front of
the number to represent an extra or missing chromosome. (Ex: +18)
Patient A’s fetus: _________
_________ _________
Scroll back up and read the section titled “Making a Diagnosis”.
6. Based on the chromosomal abnormality found in the karyotype, what is the diagnosis for Patient A’s fetus?
Click on the “Patient B” button at the bottom of the page and match the chromosomes as before.
7. Write the notation used to characterize Patient B’s fetal karyotype. Remember to scroll to the bottom of the
page to see the completed karyotype.
Patient B: _________
_________
_________
8. What is the diagnosis for Patient B?
Click on the “Patient C” button at the bottom of the page and match the chromosomes as you did with the
previous two patients.
9. Write the notation used to characterize Patient C’s fetal karyotype.
Patient C’s fetus: _________
_________ _________
10. What is the diagnosis for Patient C?
Now that you understand how a karyotype is created, it’s time to learn about how the chromosomes were
originally obtained for the karyotype. Use a search engine (such as Google) to help you answer the following
questions.
11. One method of obtaining the chromosomes necessary for a karyotype is through a process known as
amniocentesis.
a) What is tested during this process?
b) Describe how the procedure is performed.
c) Who usually receives this test?
d) When is this test usually administered?
12. Chorionic villi sampling (CVS) is a different method of obtaining chromosomes.
a) What is tested during this process?
b) Describe how the procedure is performed.
c) When is this test usually administered?
d) What is the advantage that CVS has over amniocentesis?
13. a) What is nondisjunction?
b) How does nondisjunction explain the abnormal karyotypes observed in the activity?
14. a) What is monosomy?
b) Name a condition that results from monosomy.
c) What is trisomy?
d) Name a condition that results from trisomy.
15. Choose one of the 3 patients (A, B, or C) and do further research on the condition of the patient and/or the
patient’s fetus by “googling” the condition. Fill out the table below as you find the information.
Cause
Symptoms/Characteristics
Life Expectancy
Treatments Available
Other Information
On separate piece of paper, write a letter to Mr. and Mrs. Mendel, the parents of the child. Include a brief
explanation of your testing procedure (amniocentesis or CVS) and the conclusions you have made regarding
their child’s health and gender. Explain the abnormality, its causes, and possible treatments. Remember that
this is someone’s future child, so be compassionate and use appropriate language.