Download 800X400 pixel file here

Return to Luverne Biology Main Menu
Karyotype Activity
View the actual karyotypes under the microscopes!
In this lab you will use a computer to build a karyotype of an individual.
Evaluation of the outcome will be 50% hardcopy karyotype, 30% essay (letter
to parents) and 20% quiz (rubric attached). You will download the stylized
spreads from the web site and use any paint program you choose (it just needs a
lasso selection tool).
Read the narrative below before the first lab day!
Background
Geneticists are able to use karyotypes to determine the chromosomal
complement of a cell. It wasn't until 1956 that man discovered he had 46
chromosomes, until this time he thought the number was 48. It wasn't until
1959 scientists discovered Down Syndrome was the result of an extra 21st
chromosome. That means that much of the material you are studying has been
discovered in your parent's lifetime.
Since you are already aware that the genetic material in the nucleus is DNA, we
can dispense with any lengthy explanations and get down to the business at
hand. Genes (segments of DNA) carry the code for the synthesis of proteins.
Proteins make up many structural components of living things (especially
animals), but of greater importance is their function as enzymes.
It is important to note the basic differences between single gene disorders and
chromosomal disorders. In a single gene disorder a section of DNA carries a
faulty message for protein synthesis. Genetic diseases such as hemophilia,
cystic fibrosis, and sickle cell anemia would be examples. These are often the
result of a mutation. In a chromosomal disorder the actual amount of genetic
material is affected. One of the more common chromosomal disorders would be
Down syndrome which amounts to having three 21st chromosomes. Other
chromosomal disorders are characterized by the lack of one chromosome in a
pair, or the addition or subtraction of parts of chromosomes.
The technique of karyotyping allows us to look at a stained preparation of the
chromosomes in a studied cell. These chromosomal preparations are most
easily obtained from white blood cells. A simple count and arranging of the
observed chromosomes allows us to identify many characteristics. Further
observation of banding on the chromosomes allows the determination of some
gene aberrations (mistakes). Still, most single gene mistakes go unnoticed.
(Special note: many single gene dysfunction can be determined by chemical
analysis of the cells recovered during amniocentesis.)
One common use of karyotyping would be in conjunction with amniocentesis.
This is of significant importance since it deals with the unborn fetus and allows
us the determine some genetic traits before birth. This procedure involves the
removal of a small amount of amniotic fluid from the sac surrounding a fetus.
This fluid contains fetal cells which can be cultured for two to three weeks to
produce a sufficient number of cells to reliably make a karyotype.
For the actual karyotype a cell is arrested (stopped) at metaphase by means of
chemicals. This allows us the best view of the chromosomes. A special stain is
used to help identify distinguishing bands on the chromosome as they are
spread out through the nucleus. A technician will then take a photograph of the
chromosomes. In the past this photograph was enlarged to allow a geneticist to
cut the chromosome pairs out and organize them. Today, computers can now
accomplish this task quickly and accurately.
In this activity we are simulating the process of prenatal diagnosis of a genetic
condition. You are the geneticist responsible for analyzing the karyotype of an
unborn infant. The cells used for the karyotype came from an amniocentesis.
Technology Instructions
From the website copy your assigned karyotype into your student folder. You
can drag and drop or download the jpeg image that is on a 800X400 pixel
landscape image already formatted for the activity. These files are also in the
BioStudentFile folder on the classroom computers. Make a back-up.
http://www.isd2184.net/~jensenje/biology/activities/karyotype/karyotypelab.ht
m (in biology bookmarks)
Open the file with a paint program that has a lasso selection tool (PS Elements
of AppleWorks Paint work fine). In PhotoShop you might want to resize the
canvas to give you a more usable space.
• Count your chromosomes FIRST!! •
Do not place chromosomes on top of each other!!
Use your template for the following:
Now locate one of the chromosome #1's and select it with the lasso tool. (Use
the attached guide.) Move the chromosome to the upper left corner of the
screen. Rotate left/right or flip vertical / horizontal to position you chromosome
for best viewing (orientation). Now find and move the second #1 chromosome
and position it in a similar manner. Select the writing tool to identify the
chromosomes as pair #1 (see example). [You might wish to practice selecting
and moving with the lasso on a practice file you don't have to karyotype.]
Continue on to identify all the chromosomes and position them. You will most
likely have to move some groups of chromosomes around to make room for
your work. Some of the smaller ones are difficult to identify, this is true of
actual chromosome photographs also. Do the best you can. Try to locate dark
bands and different sizing to aid your identification.
Use the information below to identify the chromosome disorder you are
working with so you can label your karyotype with the writing tool as in the
example. You must also identify the area of the karyotype that is not normaldo this with the drawing tools. Finally identify the sex of the fetus. All this info
should be added using computer tools, no writing with pen should be necessary
on your karyotype. (see rubric)
When completed Print the file. Your hard copy will be at your selected printer.
Now that you have your karyotype hardcopy and have identified your patient's
disorder, the difficult part of your assignment has begun. You are to take the
role of the doctor responsible for the mother's and family's care. Research the
condition you identified from the amniocentesis. You can use the books
available in the biology room, go to the library, and definitely do an Internet
search. Then write a letter to the parents explaining what you have discovered
(diagnosis, prognosis, future scenarios, professional guidance). Feel free to
design letterheads, assume fictitious doctor's names etc. This letter (essay) will
become 30% of your grade on this outcome. It is imperative that you make a
sound judgment supported in the essay with scientifically accurate and socially
acceptable reasoning. See rubric!!
Possible Genetic Conditions in this activity:
Down Syndrome 47 (XX) or 47 (XY) extra #21.
Edward's Syndrome 47 (XX) or 47 (XY) extra #18
Patau Syndrome 47 (XX) or 47 (XY) extra #13
Turner Syndrome 45 (XO) monosomy X
Klinefelter Syndrome 47 (XXY) extra sex chromosome
This is an example of a karyotype that would receive an evaluation in the
low C range. It lacks organization, neatness, professional finish and
creativity. You can do better!
Download 800X400 pixel file here:
Karyotype 1 Patient
Karyotype 2 Patient
Karyotype 3 Patient
Karyotype 4 Patient
Karyotype 5 Patient
Number 1
Number 2
Number 3
Number 4
Number 5
Template
Return to Luverne Biology Main Menu