Karyotypes
Name:______________________________________Date:____________Pd:_______
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping2.html
Introduction and instructions:
Karyotyping is one of many techniques that allow us to look for several thousand possible genetic
diseases in humans. When doctors use karyotypes, they take a photograph of the chromosomes in a cell
and cut out each of the chromosomes. They then organize these chromosomes by size and banding
pattern. Diploid cells have 2 of each chromosome size. Humans have 23 pairs of chromosomes. Other
species have different numbers of chromosomes.
Notation of Karyotypes: 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.
This is a male with no chromosomal disorder. Notice there are 23 pairs of chromosomes and in the lower
right hand corner, the last homologous pair is not the same size. This is because the Y chromosome is
smaller than the X. The notation for this is 46,XY. Because there are 46 chromosomes and the sex
chromosomes are an X and a Y since it is a male.
This is a female with no chromosomal disorder. Notice there are 23 pairs of chromosomes and in the
lower right hand corner, the last homologous pair is the same size. This is because every female has 2 X
chromosomes. The notation for this is 46,XX. Because there are 46 chromosomes and the sex
chromosomes are an X X since it is a female.
Watch this video: https://youtu.be/Huf1-il_p84
Occasionally non-disjunction occurs during meiosis and an individual may receive a different number of
chromosomes. An extra chromosome will give a person trisomy, three of one type of chromosome. A
missing chromosome will result in monosomy. There are a few examples of non-disjunction that result in
a baby that can survive after birth; the others are too devastating and the baby usually dies inside the
mother and a miscarriage occurs.
You will evaluate 3 patients' case histories, complete their karyotypes, and diagnose any missing
(monosomy) or extra chromosomes (trisomy). This is what actual doctors do!
Complete each patient's karyotype by matching the chromosomes with their homologous pairs. When
you find the match, click the number that the chromosome belongs over (your choices will be blue).
Remember that a typical human karyotype will have 46 chromosomes; 2 of each type. Each homologous
pair should be the same size and have the same gene banding pattern. The only exception is that males
will have a Y chromosome that is a different size than the larger X. Then, use the karyotype and following
descriptions to diagnose the patient.
Possible Diagnosis:
Normal chromosome #- symptoms due to something other than an abnormal number of chromosomes.
Klinefelter's Syndrome – Trisomy of the sex chromosome , extra X sex chromosomes.
Down's Syndrome- Trisomy 21, extra chromosome 21
Patau Syndrome – Trisomy 13, extra chromosome 13
Turner Syndrome- Monosomy of the sex chromosomes
Jacob Syndrome- Trisomy of the sex chromosome, extra Y sex chromosome
Karyotype Lab Questions
Name:_________________________________________Pd:________________Date:_______________
Introduction Questions:
1. What is a Karyotype?_________________________________________________________
2. In your own words, how is a karyotype made?
__________________________________________________________________________________
__________________________________________________________________________________
3. When a patient has only 1 of a specific chromosome, instead of a homologous pair, this is called
_____________________________________________________________________________
4. When a patient has 3 of a specific type of chromosome, instead of a homologous pair this is called
_____________________________________________________________________________
5. What is the cause of abnormal chromosome numbers?
________________________________________________________________________________
6. Do abnormal chromosome numbers always result in Down syndrome?
________________________________________________________________________________
7. What do abnormal chromosome numbers usually cause?
________________________________________________________________________________
Application Questions:
Label each Karyotype as Patient A, B or C.
____________________
__________________
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Patient A
This patient is the nearly-full-term fetus of a forty year old female. Chromosomes were obtained from
fetal epithelial (skin) cells acquired through amniocentesis. Amniocentesis is a procedure where the
doctor takes a sample of the fluid in the womb to run tests on. Amniocentesis is a higher risk procedure
that doctors usually only do when they suspect that the baby may have a chromosomal disorder. Since the
mother is in her forties and non-disjunction occurs more frequently when the mother is over thirty five
they are testing the baby to check for abnormal chromosome numbers just in case.
Notation:_________________Gender:______________________Diagnosis:_______________________
Patient B
This patient is a 28 year old who is trying to identify a cause for his/her infertility. Chromosomes were
obtained from nucleated cells in the patient's blood.
Notation:_________________Gender:______________________Diagnosis:_______________________
Patient C
This patient died shortly after birth, with a multitude of anomalies, including polydactyly (more than 10
fingers) and a cleft lip. Chromosomes were obtained from a tissue sample.
Notation:_________________Gender:______________________Diagnosis:_______________________
1. What are 3 ways a doctor can get a sample of chromosomes?
(hint: how did they get them from our patients)
____________________
______________________
_____________________
2. In your own words, describe what an amniocentesis is.
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