6.5 Karyotyping Webquest
Name:
Date:
Block:
Overview: Karyotypes offer information that allows genetic counselors to offer guidance to prospective parents and
patients that suffer from chromosomal abnormalities. In this activity you will use Karyotypes to make diagnoses for
three patients.
Instructions
 Open this Google doc, make a copy and save it in your Unit 6 Folder with your name and date in the file name of
the document.
 Use the links in this assignment to complete the questions.
 Know the information in this webquest so that you can complete the Human Genetics packet that you will
receive during our next class.
Part 1 Meiosis Review
Go to the link titled Using Karyotypes to Diagnose Genetic Disorders.
Scroll down to the section titled: “Too many or too few chromosomes” and read the information. The
following concepts address how cells end up with too many or too few chromosomes. You may copy and
paste definitions for the items below.
a. Describe the content of gametes produced when chromosomes are not distributed properly.
one cell may get two copies of a chromosome, while another cell gets
none. Incorrect distribution of chromosomes is called nondisjunction
b. Define the term trisomy: A zygote with 3 copies of a chromosome
c. Describe how trisomy occurs: A sperm or egg cell with too many chromosomes
participates in fertilization, it will produce a zygote with too many
chromosomes
d. Define the term monsomy: A zygote that is missing a chromosome is said to
have monosomy
e. Describe how monsomy occurs: A sperm or egg cell with too few chromosomes
participates in fertilization, it will produce a zygote with too few
chromosomes.
f. List three genetic disorders resulting from too many or too few chromosomes
 Klinefelter Syndrome (XXY)
 Turner Syndrome (X)
 Down Syndrome (Trisomy 21)
g. Define the term chromosome deletion: pieces of chromosomes are lost or rearranged during
meiosis. HOMOLOGOUS chromosomes swap pieces AKA CROSSING OVER
DURING MEIOSIS . When genetic material is missing, a chromosome is
said to have a deletion.
h. Define the term chromosome translocation: A translocation is a chromosome
rearrangement in which part of a chromosome breaks off and then
reattaches to a non-homologous chromosome DURING MEIOSIS
CROSSING OVER.
i.
Fill in the blank: When monosomy or trisomy involves sex chromosomes, individuals
usually survive and many are quite healthy.
Part 2 Karyotyping Activity.
You will be taking screen shots and pasting them into this document. Go to the link titled Karyotyping Activity
1. Introduction
a. What is a karyotype and how is it prepared? A picture of your chromosomes taken during mitosis
.
b. State what the bands on the stained chromosomes represent the base pairs Adenine (A) and Thymine
(T) producing a dark band
c. List (in a sentence) the characteristics used to compare chromosomes in a karyotype.
Place chromosomes in order by length, longest first. Placement of centromeres (areas where the two
chromatids are joined), and the location and sizes of G-bands also determines the order.
2. Click on Patient Histories
at the bottom of the
webpage.
Patient A is the nearlyfull-term fetus of a forty
year old female.
Chromosomes were
obtained from fetal
epithelial cells acquired
through amniocentesis
Click on Patient A to
place the chromosome
provided in the right
place in the Karyotype.
Obtain a screen shot of your completed karyotype and insert it in the space below
a. State the chromosome notation you would use to characterize Patient A’s Karyotype:
_47XX + 21___
b. What diagnosis would you give patient A?
Down’s Syndrome.
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.
Click on Patient B to place the chromosome
provided in the right place in the Karyotype.
a. State the chromosome notation you would use
to characterize Patient B’s Karyotype: 47 XXY
b. What diagnosis would you give patient B?
Kleinfelter’s Syndrome
Patient C died shortly after birth, with a multitude of anomalies, including polydactyly and a cleft lip.
Chromosomes were obtained from a tissue sample.
Click on Patient C to place the chromosome provided in the right place in the Karyotype.
a. State the chromosome
notation you would use to
characterize Patient C’s
Karyotype: 47 XY +13
b. What diagnosis would you
give patient C?
Trisomy 13 Syndrome
Be prepared to ask questions and check your work during our next class. You will be expected to know this
material for the completion of the 6.5 Human Genetics packet (20 points possible.)