Teacher preparation for the slide activity:

You will need to obtain slides of chromosomes to be viewed under an oil immersion microscope.

My I suggest Carolina Biological . They have slides listed under genetics which will show the actual chromosomes. Here is a brief list of what you can order.

Carolina Biological Supply Company

Catalog #67

1-800-334-5551

P7-G500 Human female 46,XX (normal) $17.50 ea.

P7-G502 Human male 46,XY (normal) $17.50 ea

P7-G512 Human chromosomes Trisomy 21 Down Syndrome (47,XX,+21) $17.65 ea

P7-Human chromosomes 14/21 translocation carrier, spread $17.50 ea

After you obtain the slides cover the name with masking tape and reliable as slides 1,2,etc.

Have the students complete the worksheet using each slide. Remember the need to be viewed with oil.

Student Activity sheet

Geneticists use karyotypes to determine genetic abnormalities. They examine the chromosomes for structural defects,having too many or too few chromosomes as well as chromosome location. By determining these factors they are able to diagnosis genetic abnormalities.

Your job is to count the chromosomes you see under the microscope and determine if there are too many,too few or the correct number of chromosomes on each slide. Answer the questions and record the information below.

1. Draw and describe a homologous chromosome pair
2. How many chromosomes are found in a "normal" human cell?
3. Where are the sex chromosomes located on a karyotype ?
4. How can you determine male from female on a karyotype? Explain.

Slide 1:

chromosome number ______

too many ____ too few ____ correct number _____

Describe the structure of the chromosomes.

Slide 2:

chromosome number ______

too many ____ too few ____

Describe the structure of the chromosomes.

Slide 3:

chromosome number ______

too many ____ too few ____

Describe the structure of the chromosomes.