Name: ________________________________
Karyotyping Activity
In this activity, you will use a computer model to look at chromosomes and prepare a
karyotype. You will diagnose patients for abnormalities and learn the correct notation for
characterizing karyotypes.
Write all of your answers on a separate sheet of paper. Attach the answers to this sheet and
turn both in.
Pre-lab Vocabulary:
Define the following terms.
1. Karyotype
2. Chromosome
3. Autosome
4. Sex chromosome
5. Homologous
6. Amniocentesis
Karyotyping:
Go to the website:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
Read through the introduction and answer the following questions:
1.
2.
3.
4.
What is a karyotype?
How many times a year is this type of analysis performed?
How many pairs of chromosomes do humans have?
During mitosis, cells are blocked (stopped) and the condensed chromosomes are stained
with what dye?
5. The dye stains regions that are rich in ____ and ___.
6. The thinnest band of dark regions contains ___ base pairs and probably ___ of genes.
Scroll to the bottom of the page and click on the link “Patient Histories.” You will start with
patient A.
Patient A
Patient A is the nearly-full-term fetus of a forty year old female. Chromosomes were obtained
from fetal epithelial cells acquired through amniocentesis.
A 1. How old is patient A? Who is the karyotype actually of?
A 2. The karyotype was generated through the process of amniocentesis. Look up the word
amniocentesis. What does it mean?
Click the hyperlink “Complete Patient A’s Karyotype.”
Complete Patient A’s karyotype.
Interpreting the Karyotype
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.
A 3. Given the information provided above, what notation would you use to characterize
Patient A’s karyotype? _______________
A 4. Is it a male or a female? Why?
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 inviable. 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.
A 5. What diagnosis would you give patient A? Write the correct diagnosis on your sheet and
explain why you chose what you did.
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 Syndrome
Trisomy 21, extra 21 chromosome
Trisomy 13 Syndrome
extra chromosome 13
A 6. Do some research on this disorder. Write at least on paragraph that describes the
characteristics of the disorder. Include a picture with your description.
Patient B
Go back to “Patient Histories.” Read the background on Patient B.
B 1. How old is Patient B?
B 2. How did they obtain Patient B’s chromosomes?
Now click on “Complete Patient B’s Karyotype.”
Complete Patient B’s karyotype.
Interpreting the Karyotype
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.
B 3. Given the information provided above, what notation would you use to characterize
Patient B’s karyotype? _______________
B 4. Is it a male or a female? Why?
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 inviable. 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.
B 5. What diagnosis would you give Patient B? Write the correct diagnosis on your sheet and
explain why you chose what you did.
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 Syndrome
Trisomy 21, extra 21 chromosome
Trisomy 13 Syndrome
extra chromosome 13
B 6. Do some research on this disorder. Write at least on paragraph that describes the
characteristics of the disorder. Include a picture with your description.
Patient C
Go back to “Patient Histories.” Read the background on Patient C.
C 1. Is Patient C a baby?
C 2. How did they obtain Patient C’s chromosomes?
Now click on “Complete Patient C’s Karyotype.”
Complete Patient C’s karyotype.
Interpreting the Karyotype
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.
C 3. Given the information provided above, what notation would you use to characterize
Patient C’s karyotype? _______________
C 4. Is it a male or a female? Why?
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 inviable. 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.
C 5. What diagnosis would you give patient C? Write the correct diagnosis on your sheet and
explain why you chose what you did.
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 Syndrome
Trisomy 21, extra 21 chromosome
Trisomy 13 Syndrome
extra chromosome 13
C 6. Do some research on this disorder. Write at least on paragraph that describes the
characteristics of the disorder. Include a picture with your description.
Conclusion:
Conclusion 1. Each of these disorders includes the process of nondisjunction. Look up what
nondisjunction means. What happens during this process? Why are these disorders a result of
nondisjunction?
Conclusion 2. Why might a person be interested in obtaining a karyotype?