Teacher's Guide for "A Chromosome Study"

This activity requires students to cut and paste paper models of chromosomes in order of largest to smallest. The chromosomes must be paired with their homologs. Students will often have trouble finding pairs and getting the exact matches and size orientation. Generally, when grading I look to see if it look mostly right, and look for the specific abnormality showing an extra chromosome.


There are enough karyotype sheets, that students can have different ones. For the normal section. Use Normal Girl and Normal Boy sheets.

For the abnormal, there are 4 sheets, so again each group can have a different one.

Sheet B - Klinefelter Syndrome (XXY)


Sheet D - Patau Syndrome
(extra chromosome 13)

Patau Syndrome

Sheet A - Down Syndrome

Down Syndrome

Sheet C - Edward Syndrome
(extra chromosome 18)

Edward Syndrome


Do NOT give students the abnormal sheets until the normal one is finished. This will prevent students from getting chromosomes from both sets mixed up.

This lesson generally takes 2 class periods. 1st day - go over the lab and do the "normal" karyotype. 2nd day, do the abnormal karyotype.

There are other karyotype resources that might be appropriate for your class

Karyotyping Activity - this one uses www.biology.arizona.edu to practice karyotypes and includes explanations for several genetic disorders, worksheet follows a simulation on the site

Karyotype Analysis - flash simulation where students can click and drag chromosomes to arrange them by size and diagnose a disorder.