Name: _____________________________________________________ Date: _____________ Period: ______
Building a Karyotype: A Chromosome Study (Patient B)
Francine is 5 months pregnant. Both she and her husband Lawrence are expecting the birth of their first child and are very
excited. Francine just completed a routine ultrasound and was told by her doctor there is a potential problem. It appears that the
unborn baby is not as grown as he/she should be after 5 months. For this reason, her doctor suggested Amniocentesis. This
process allows cell from the unborn child to be collected and analyzed. A picture of the unborn child’s chromosomes has been
taken and is partially arranged on the following page.
1.
Cut out the unpaired chromosomes in the section titled “Cut out chromosomes here”. Match them up with the labeled
chromosomes on the other half of the paper. Each labeled chromosome will have an identical match (size, shape, and color
banding).
2.
Glue each identical pair of chromosomes next to its match and then answer the questions below.
A karyotype is a picture of an organism’s chromosomes. Cells can be obtained from an unborn child using amniocentesis. Once
obtained, the cells are stained so the chromosomes can be more visible underneath the microscope. A picture of the chromosomes
is then taken and the chromosomes are arranged in pairs in order from largest to smallest, with the sex chromosomes being placed
at the end.
Once created, the karyotype can be analyzed and a notation described. The 1 st part of a notation is to record the total number of
chromosomes visible in the final karyotype. The 2nd part of a notation is to list the sex chromosomes that are visible in the final
karyotype. The 3rd part of the notation is to list which chromosome number is altered. A plus sign (+) means the person has an
extra chromosome and a minus sign (-) means they are lacking a chromosome. The table below is a partial list of some of the
chromosome disorders. The notation for a male with Warkany Syndrome would be: 47, XY, +8.
Down Syndrome
Patau Syndrome
Edward Syndrome
Warkany Syndrome
Klinefelter Syndrome
Turner Syndrome
3.
Three chromosome 21’s
Three chromosome 13’s
Three chromosome 18’s
Three chromosome 8’s
Two X and one Y chromosome
One X chromosome
Examine the cut-out karyotype you created to answer the next set of questions.
a.
How many chromosomes does patient B have?
b.
What is the normal chromosome number for this species?
c.
How many chromosomes are normally found in gametes of this species?
d.
What is the notation used to describe the chromosome arrangement of patient B?
e.
What is the name of the genetic disorder patient B will suffer from? (use chart above)
Answer the following questions using your best writing skills (complete sentences).
4. How does the arrangement of chromosomes differ in a gamete (egg cell or sperm cell) versus a somatic (body) cell?
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5.
Is your karyotype made from a gamete or somatic cell? Be sure to explain how you can tell.
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The final two chromosomes are called sex chromosomes. They determine the gender of the individual. The longer of
the chromosomes is called the “X” chromosome. The shorter of the two (if present) is called the “Y” chromosome.
Some organisms, including humans, have paired sex chromosomes. This combination is referred to as XX
chromosomes. The XX combination produces a female and the XY combination produces a male.
8.
6.
Which sex chromosomes are present in patient B? (i.e. XX, XY?)
7.
What is the gender of patient B?
Explain to Francine and Lawrence what you have learned (gender & health) about their unborn child.
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