Question

Karyotypes can be studied to determine an organism’s chromosomal makeup and to detect genetic defects. Down syndrome is a genetic disorder that is also called trisomy 21. What would trisomy 21 look like in a karyotype?
missing chromosome 21
extra chromosome 21
missing sex chromosome
extra sex chromosome

Answer 1

Extra chromosome 21 — a karyotype for trisomy 21 shows three copies of chromosome 21 (three #21s instead of the normal two).