Download Some chromosomal abnormalities that can be detected by

Karyotype Analysis
Name
Date
Period
Directions: Use the karyotype you completed to answer the following questions about the person whose
chromosomes you looked at.
1. What set of chromosomes (“photograph”) did you use?
2. What is the gender of the person whose chromosomes you analyzed?
3. How did you determine whether your karyotype was male or female?
4. Complete the following table with the information provided on the back of this sheet and the information of
others in the class:
Karyotype #1
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Karyotype #4
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Karyotype #2
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Karyotype #5
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Karyotype #3
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Karyotype #6
Individual is a
Number of chromosomes
Normal or Abnormal (circle one)
If abnormal, what is the name of the disorder?
Complete the Debrief Questions on the following pages.
Some chromosomal abnormalities that can be detected by karyotyping are
listed below:
Abnormality
Extra chromosome 21
Down Syndrome
XXY
Klinefelter Syndrome
XYY
Double Y Syndrome
XXX
XO - missing sex chromosome
Turner Syndrome
Partial chromosome 5
Cru de chat Syndrome
Abnormal X chromosome
Fragile X Syndrome
Trisomy 18
Edwards Syndrome
Trisomy 13
Patau Syndrome
Effects
Associated with mental retardation,
characteristic facial features and
stature, heart defects, respiratory
infection, leukemia, and Alzheimers
disease; occurs in 1 in 700 births in
U.S.
Typically sterile males with
abnormally small testes, some
female characteristics, normal
intelligence; occurs in 1 in
2000 births
Affected individuals tend to be taller
as a group, increased activity,
delayed mental maturity, sometimes
normal intelligence
Distinguished from normal XX
females only through karyotyping;
occurs in 1 in 1000 births
Sterile females with immature sex
organs, normal intelligence; occurs
in 1 in 5,000 births
Associated with small head,
characteristic cry and facial
features, death in infancy or early
childhood
Common genetic cause of mental
retardation
Affects girls 3 times more than boys.
Low birth weight, mental retardation,
low set ears, small jaw, hand
abnormalities
Cleft lip, cleft palate, low-set ears,
small eyes with defect in the iris.
Rarely survive until adulthood.
Debrief Questions
1.
Achondroplasia is a form of short-limbed dwarfism. The word achondroplasia literally means "without cartilage formation."
Cartilage is a tough but flexible tissue that makes up much of the skeleton during early development. However, in
achondroplasia the problem is not in forming cartilage but in converting it to bone (a process called ossification), particularly
in the long bones of the arms and legs. Achondroplasia is similar to another skeletal disorder called hypochondroplasia, but
the features of achondroplasia tend to be more severe.
Mutations in the FGFR3 gene cause achondroplasia. The FGFR3 gene, located on chromosome 4, provides instructions for
making a protein that is involved in the development and maintenance of bone and brain tissue. Two specific mutations in
the FGFR3 gene are responsible for almost all cases of achondroplasia. Researchers believe that these mutations cause the
FGFR3 protein to be overly active, which interferes with skeletal development and leads to the disturbances in bone growth
seen with this disorder. Achondroplasia is inherited in an autosomal dominant pattern, which means one copy of the altered
gene in each cell is sufficient to cause the disorder. It is a dominant trait.
Based on the information above, label chromosome pair #4 on the karyotype you made for a person who
does not have Achondroplasia. One allele should be labeled on one chromosome; the other allele on the
other chromosome.
2.
How do people inherit achondroplasia? Support this with evidence from your karyotype.
3.
What is the genotype of a person without this disorder?
4.
Where did each allele, that when combined to form the person's genotype, come from?
5.
What does that mean for the rest of the traits a person inherits? How do they obtain 2 alleles for each trait?
6.
Some genetic disorders may result from having more than 46 chromosomes or less than 46 in the nucleus of the fertilized egg
(that of course was you before your cells multiplied to "grow"). How do you think a fertilized egg might come to have an
abnormal number of chromosomes? Hint: What had to combine in order to make a fertilized egg?
7.
What information can you get from a karyotype? List 2-3 pieces of information.
8.
What information can you NOT get from a karyotype? List 2-3 pieces of information