Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Human Karyotyping Lab
Background: Occasionally chromosomal material is lost or rearranged during the formation of
gametes or during cell division of the early embryo. Such changes, primarily the result of
nondisjunction or translocation, are so severe that the pregnancy ends in miscarriage — or
fertilization does not occur at all. It is estimated that one in 156 live births have some kind of
chromosomal abnormality. Some of the abnormalities associated with chromosome structure and
number can be detected by a test called a karyotype.
A karyotype can show prospective parents whether they have certain abnormalities that could be
passed on to their offspring, or it may be used to learn the cause of a child’s disability.
Karyotypes can also reveal the gender of a fetus or test for certain defects through examination
of cells from uterine fluid during a procedure called amniocentesis or through sampling of
placental membranes. Over 400,000 karyotype analyses are performed each year in the U.S. and
Canada.
To create a karyotype, chromosomes from a cell are stained and photographed. The photograph
is enlarged and cut up into individual chromosomes. The homologous pairs are identified and
arranged in order by size (with the exception of the sex chromosomes; these appear last). These
tests are typically done on a sample of blood, although any body cell could be used. The cell
must be undergoing mitosis, preferably in metaphase, so that the chromosomes are replicated,
condensed, and visible under a microscope (adapted from:
http://www.slic.wsu.edu/bios/biol107/107Karyotypesp05.pdf)
Purpose: The purpose of this laboratory experience is to
1. Understand what a karyotype is and how it is performed.
2. Understand the reason for performing a karyotype, especially for those with a higher risk
of genetic defect in their lineage.
3. To determine what genetic defect is present in a chromosome sample.
4. To investigate a variety of genetic disorders that commonly occur and are studied in
biology classes.
Materials: The following materials are needed to perform this laboratory experience:
Scissors
tape
ruler
small envelope
karyotype samples
Procedure:
1. Using the attached sheets, complete four different karyotypes: one normal male, one
normal female, two different disorders of your choice out of the four.
2. Working slowly and carefully, using scissors cut out the chromosome on one page
labeled “1” and find its’ EXACT match elsewhere on the page (it will not be numbered).
Cut out this chromosome and tape BOTH chromosomes side by side on a “data page”
that has the heading filled out.
3. Continue this procedure until you have matched all chromosomes and taped each of them
in the corresponding place on the data page.
4. If you are caught short of time, use the coin envelope to store any chromosomes you may
have clipped out and not matched. DO NOT CUT OUT ALL CHROMOSOMES AND
THEN ATTEMPT TO MATCH THEM!!! Cut out only one at a time or you will lose
chromosomes.
5. In the event that you have an extra chromosome, DO NOT THROW IT OUT! It is the
chromosome that causes your mutation/disorder and you must match it correctly.
1
Name: __________________
date of Lab _______________ Lab Partner/s: ________________
6. Once your chromosomes are all cut out and included in the karyotypes, answer the
questions and complete the lab.
2
Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Questions: Answer the following questions before turning in your lab.
1. What four karyotypes did you choose to complete?
2. How could you determine if your karyotype was male or female?
3. Complete the following table:
Karyotype #1
Karyotype #2
Individual is a ________ Individual is a _______
Number of
Number of
chromosomes: _______ chromosomes: _______
What is the sex? _____
What is the sex? _____
Normal or Mutated
Normal or Mutated
(circle one)
(circle one)
If mutated, name the
If mutated, name the
disorder below:
disorder below:
________________
_______________
Karyotype #3
Individual is a _______
Number of
chromosomes: _______
What is the sex? _____
Normal or Mutated
(circle one)
If mutated, name the
disorder below:
_______________
Karyotype #4
Individual is a _______
Number of
chromosomes: ___
What is the sex? _____
Normal or Mutated
(circle one)
If mutated, name the
disorder below:
_______________
After completing the karyotypes attached, go to the website at the end and do the activity. Give
answers
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Normal karyotype #1
4
Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Normal karyotype #2
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Set A
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Set B
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Set C
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Set D
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Online Part of Lab:
This exercise is a simulation of human karyotyping using digital images of chromosomes from
actual human genetic studies. You will be arranging chromosomes into a completed karyotype,
and interpreting your findings just as if you were working in a genetic analysis program at a
hospital or clinic. Imagine that you were performing these analyses for real people, and that your
conclusions would drastically affect their lives.
G Banding
During mitosis, the 23 pairs of human chromosomes condense and are visible with a light
microscope. A karyotype analysis usually involves blocking cells in mitosis and staining 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 bands represent single genes, 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 entire genetic information for one bacterium.
The analysis involves comparing chromosomes for their length, the placement of centromeres
(areas where the two chromatids are joined), and the location and sizes of G-bands. You will
electronically complete the karyotype for three individuals and look for abnormalities that could
explain the phenotype.
Your assignment
Karyotyping is one of many techniques that allow us to look for several thousand possible
genetic diseases in humans. You will evaluate 3 patients' case histories, complete their
karyotypes, and diagnose any missing or extra chromosomes.
Patient A is the nearly-full-term fetus of a forty year old female. Chromosomes were obtained
from fetal epithelial cells acquired through amniocentesis.
Patient B is a 28 year old male who is trying to identify a cause for his infertility. Chromosomes
were obtained from nucleated cells in the patient's blood.
Patient C died shortly after birth, with a multitude of anomalies, including polydactyl and a cleft
lip. Chromosomes were obtained from a tissue sample.
Attached is the website with the karyotypes. Do the three patient karyotypes and determine the
diagnosis. http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
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Name: __________________
date of Lab _______________ Lab Partner/s: ________________
Diagnosis patient 1: 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.
A1. 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 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 2. What diagnosis would you give patient A?
B 1. What notation would you use to characterize Patient B's karyotype? ________
B 2. What diagnosis would you give patient B?
C 1. What notation would you use to characterize Patient C's karyotype? _______
C 2. What diagnosis would you give patient C?
Diagnosis
Normal # of chromosomes
Klinefelter's Syndrome
Down's Syndrome
Trisomy 13 Syndrome
Chromosomal Abnormality
Patient’s problems are due to something other than an abnormal number of chromosomes.
One or more extra sex chromosomes (i.e., XXY)
Trisomy 21, extra chromosome 21
Extra chromosome 13
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