Name _________________________________________________
Date __________
Activity: Karyotyping Human Chromosomes
Goals:
1. To select and organize homologous chromosomes on a
karyotype chart.
2. To simulate karyotying, one of the many techniques
A Human Karyotype
that allow scientists to look for thousands of possible
genetic diseases in humans..
Background Information: Thread-like strands of DNA called chromatin replicate during
the first stage of cell division. During the prophase stage of mitosis, the 23 pairs of
chromatin strands coil tightly and become visible under a microscope. The X-shaped
pairs of chromosomes that result from this coiling represent the image most people
have of chromosomes. When the chromosome pairs (sister chromosomes) separate
and move toward opposite poles individual chromosomes can be seen for the first time.
Karyotyping is one of many techniques used by scientists to look for genetic diseases.
Karyotyping involves halting cells after separation from sister chromatids has occurred
and staining them with a dye (Giemsa dye). The dye stains the areas of each
chromosome that have large regions of Adenine (A) and Thymine (T) base pairs
together producing dark bands.
Many people think that the bands represent individual genes. This is a misconception!
In fact, even the thinnest dark bands may contain over a million base pairs and
potentially hundreds of genes.
The analysis of chromosomes in a karyotyping activity involves comparing
chromosomes for their length, the placement of their centromeres (areas where the two
chromatids were joined), and the location and sizes of their dark bands (called Gbands). (This information came from:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
Materials: A photograph of a chromosome smear containing 23 randomly distributed
human chromosomes, an incomplete karyotyping chart with 23 chromosomes,
hand lenses, scissors, glue or paste.
Procedure:
1. What I Know: Write two sentences describing what you already know about
karyotypes.
2. Cut out each randomly distributed chromosome and arrange it on the karyotpe
chart with its matching pair to create a complete human karyotype containing 23
homologous chromosome pairs. It is best to cut out one chromosome at a time
and paste it onto the karyotype chart with its match.
3. What I Observed: This will be the completed karyotype chart on the last page of
this packet. The chromosomes should paired and placed in order from 1 -23
(pairs).
4. Questions: Answer the following questions in complete statements.
a. Karyotype analyses are performed in hospital labs and clinics over
400,000 times a year in the U.S. and Canada.
1. Based on your own experiences with this karyotyping
simulation, what personality traits would a scientist or
technician have to have to be good at karyotyping?
2. Would you be interested in a career that involved doing
karyotypes? Explain your answer.
b. Scientists complete karyotypes for real people and their results
sometimes drastically affect their lives. Log on to:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
and complete a karyotype simulation for one of the patients provided.
1. Tell the patient whose karyotype you completed. (Was it Patient A, B,
or C?)
2. Explain the condition or problem that the patient experienced.
5. What I Wonder: Pose a question that you may still have concerning karyotype.
6. Claim and Evidence Writing Prompts: Use the following prompts to help you
construct your lab conclusion, What I Learned.
 Goal: State the goal of this lesson.
The goal of this lesson is…
 Claim: What did you learn from the activity that satisfies the goal of this
lesson? This is an I Learned statement.
I learned that…
 Evidence: How can you prove from your observations that you learned
what you claim? This can be a general statement that you will explain in
detail in your explanation.
I know this because….
 Explanation: Use specific data from your observations to support your
claim and describe the evidence. Use details to support your claim.
 Concluding Statement: Reword the goal and either add information you
learned about the topic from your text book, class discussions, and/ or
personal research OR you can extend the statement by adding a relevant
question.
7. What I Learned: Write at least a one paragraph summary of what you learned
from completing this activity. Use the Claims and Evidence Writing Prompts to
help you compose your summary.
Human Karyotype Chart
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