Download How can Karyotype Analysis Explain Genetic Disorders

How can Karyotype Analysis Explain Genetic Disorders??
Background:
A karyotype is a picture in which the chromosomes of a cell have been stained so that the banding
patterns of the chromosomes appear. Cells in Metaphase of cell division are stained to show distinct
parts of the chromosome. The cells are then photographed through the microscope and the photograph
is enlarged. The chromosomes are then cut from the photograph and arranged in pairs according to
their size, arm length, centromere position, and banding patterns. Karyotypes have become of
increasing importance to genetic counselors as disorders and diseases have been traced to specific
visible abnormalities of the chromosomes.
Problem:
Researchers have been studying the population of a rare insect, Insecta amadoricus, found only on the
Amador Valley High School Campus. The researchers have observed various forms of the insect and
have concluded that many of these forms are the result of genetic disorders.
You will prepare Karyotypes of the insects found on AVHS’s campus and analyze them for
chromosomal abnormalities. Furthermore you will identify the disorder based on your analysis.
Procedure:
1. For this investigation you will first need to recognize the chromosomal karyotype for a normal
male and female. Study the figures below (Figure 1). Note the difference in the last pair of
chromosomes. These are the sex chromosomes and determine if the insect will be male or female.
SORRY NO PICTURES ON-LINE
2. Along with normal Karyotype, you will need to know what genetic disorders you are looking for in
your insects.
 Size reduction disorder:
Appears when there is a
monosomy of the sex
chromosomes. A single large
sex chromosome makes a small
female insect while a single



small sex chromosome makes a
small male insect. (Figure 2)
Clear wing disorder: Appears
to result from a trisomy of the
2nd chromosomal pair. The
extra chromosome produces a
sterile insect that lacks coloring
in its wing. (Figure 3)
Duplication Disorder: Results
from duplication in a
chromosome. A repeated gene,
from this duplication causes the
insect to produce 2 heads. This
duplication also produces
banding on the wings and
additional body segments.
(Figure 4)
Deletion Disorder: A portion of
the sex chromosome is missing,
deleted. This deletion reduces
the number of body segments,
and in turn reduces the body
size. (Figure 5)
3. Collect your 6 karyotypes from the head insectologist, your teacher.
4. Have your team make a hypothesis as to what disorder will appear the most? Write your hypothesis
in the space provided.
5. Cut out the chromosomes from each insect and paste them onto the appropriate karyotype space.
Make sure you paste your chromosomes with their correct partner in the correct order (Compare
them to the Figure 1- the normal karyotypes.) The centromere should be directly on the line.
6. Once all insects’ chromosomes are pasted on the sheet, answer the question on the back.