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Transcript
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