Download Insect Karyotyping

Name: ________________________________________________
Block: ___________
Insect Karyotyping
A karyotype is a picture of all the chromosome pairs an organism has. The organism’s
chromosomes are stained to show patterns of banding and a photograph of those chromosomes is
then taken, cut, and put into pairs arranged by size, arm length, centromere position, and banding
patterns.
Changes in chromosome number or differences in banding patterns may indicate genetic
disorders. Monosomy is when a cell has only one chromosome of a pair of chromosomes.
Trisomy is when a cell has an extra copy of a chromosome, so that there are three of that type of
chromosome rather than two. Sometimes part of a chromosome is missing – bands that should be
there are not. This is known as deletion. Sometimes chromosomes have repeated sections that
cause them to be larger than normal, this is known as duplication.
There is a certain (fictional) species of insect that normally has three pairs of chromosomes – two
pairs of body chromosomes and one pair of sex chromosomes. Their normal karyotypes and
genotypes are shown in Table #2.
However, sometimes these insects have chromosomal disorders in their karyotypes that cause
certain disorders. These disorders are listed in Table #1. Errors in a single chromosome can
cause multiple problems in these insects because there are many genes on each chromosome.
You are a researcher who has been given karyotypes of the chromosomes for six different
insects. You should use these karyotypes to determine the gender of each insect, what disorders
(if any) each insect has, and the chromosomal errors that caused each disorder.
Directions
1. Read Table #1 – Genetic Disorders of Insects to become familiar with the different
kinds of disorders and the errors they cause.
2. Look over Table #2 – Normal Karyotypes to become familiar with how a normal
insect’s karyotype should look.
3. Examine Table #3 – Insect Karyotypes and determine each of the following:
a. Determine the gender of each insect.
b. Circle the genetic disorder that has taken place, (if there is one).
c. Circle the chromosome error that has occurred, (if there is one).
4. Answer each of the questions in the Analysis/Matching sections.
Table #1: Genetic Disorders of Insects
Disorder
Size Reduction Disorder
Clear Wing Disorder
Chromosome Error
Only one sex chromosome
(Monosomy).
 A single large chromosome
produces a tiny female.
 A single small chromosome
produces a tiny male.
Trisomy of the second
chromosome pair
 Produces infertile insects
with clear wings.
Duplication Disorder
Duplication of a part of the
first chromosome (which makes
the chromosome appear larger
than normal)
 Produces a two-headed
insect with banded wings
and additional body
segments.
Unsegmented Disorder
Deletion of a small part of the
large sex chromosome (which
makes the chromosome smaller
than normal)
 Produces a small insect with
no body segmentation.
Phenotype
Table #2: Normal Karyotypes
Sex Chromosomes
Body Chromosomes
Normal
Male
Normal
Female
Table #3: Insect Karyotypes – Circle the correct answer for Gender, Genetic Disorder and
Chromosome Error.
Insect
1
2
Karyotype
Gender
Genetic
Disorder
Chromosome
Error
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
3
4
5
6
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
Size
Reduction
Trisomy
Male
Clear Wing
Monosomy
Female
Duplication
Deletion
Unsegmented
Duplication
None
None
Analysis:
1. What is a Karyotype? _____________________________________________________
_______________________________________________________________________
2. How are chromosome pairs arranged? ________________________________________
_______________________________________________________________________
3. How can genetic disorders be indicated?
a. _________________________________________________________________
b. _________________________________________________________________
4. How many disorders affect the gender (sex) of the insect? Which one(s)? ____________
_______________________________________________________________________
5.
If you had a small insect with no body segments and clear wings, what disorders may it
have? __________________________________________________________________
Matching – Put the letter of the correct answer in the space provided.
_____ 6. Monosomy
A. Part of a chromosome is missing.
_____ 7. Trisomy
B. Only one chromosome of a pair of chromosomes is
present.
C. Repeated sections of a chromosome that cause them to
be larger than normal.
D. A cell has an extra copy of a chromosome, so there are
three chromosomes rather than two.
_____ 8. Deletion
_____ 9. Duplication
Design an Insect – Use the Karyotype below to draw and describe the insect.
Drawing
Gender
Genetic
Disorder
Chromosome
Error
(List all that apply)
(List all that apply)