During this chromosome lab, the students prepare,

develop and stain their won chromosomes. The metaphase

spread is photographed and the students then do the

karyotyping of their own chromosomes. Students will get a

feeling of accomplishment and excitement over the

numerous, but simple steps that are required.
 

A note of caution: this lab requires the withdrawal of blood from the arm by a qualified

individual. The overview of the lab procedure is rather straightforward. A blood sample is taken

and white blood cells grown in a special medium for three days under the influence of the mitotic

stimulant, phytohemaglutinin. After 72 hours, Colcemid, a chemical that inhibits spindle

formation, is added. The red blood cells are exploded with a hypotonic solution of potassium

chloride. The remaining swollen white blood cells are fixed with alcohol and acetic acid. The

resulting cells are dropped from a pasteur pipette onto a clean slide, causing the cells to splatter

and separate. When the slide is stained with giemsa stain, the chromosomes of the individual

white blood cells are visible (Macgregor & Narley 1983).

    Laboratory Procedures