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Biology-Mr. Willets
Karyotype Analysis
A karyotype is a picture in which the chromosomes of an organism have been arranged in pairs according to their size, shape, location of centromere, and any other easily seen characteristics. Karyotypes can be used to identify certain genetic abnormalities in the organism.
Below are two karyotypes (male and female) for a fictitious insect. Note that there are three pairs of chromosomes and that they are numbered. In the female, the members of the third pair match each other (XX). In the male, the third pair is not matched (XY). This is the same situation as is found in humans. The XX or XY are called the _______ chromosomes. The other pairs are called the __________________________
Please note that when the chromosomes are arranged to make a karyotype, the centromeres are placed on the line provided.
Researchers have discovered some unusual phenotypes among these insects and have examined the chromosomes in an attempt to explain them. There are 4 disorders that have been identified and described below.
You have available pictures of the chromosomes of 6 insects (click on "Chromosomes"above). These were taken during metaphase when the chromosomes were somewhat spread out. You are to arrange each of these chromosome groups into karyotype form and match the insect with the disorder (if it has one) To do this, carefully cut out the chromosomes and glue them in the proper spots on the sheet provided (click on "Karyotype Form" above).. You will then fill out the table, indicating the sex, the disorder and the chromosome error for each. There are also some questions to answer.
Size Reduction Disorder-Caused by Monosomy X - a single X chromosome without another X or Y. This produces a small female insect.
Clear Wing Disorder- Caused by Trisomy-2. (3 members of pair #2) This produces a wing without spots.
Duplication Disorder-Caused as a result of chromosome one having additional genetic material. The insect has two heads, additional body segments and banding on the wings.
Unsegmented Disorder-Caused by a deletion of a section of an X chromosome. This produces an insect with an unsegmented body and reduced in size.