In a typical karyotype worksheet, students are presented with a picture of scrambled chromosomes and must arrange them. Below are the answers for a and a Standard Normal Female (46,XX) .
Although chromosome 21 is slightly larger than 22 historically, the Denver System orders primarily by size but groups acrocentric chromosomes together. Both 21 and 22 are acrocentric and very short, so they fall into Group G. The numbering (21 vs. 22) is a historical artifact based on earlier technology; under the microscope, they look similar in size and shape. denver system worksheet karyotype answers
| Group | Chromosome Numbers | Visual Identification Key | | :--- | :--- | :--- | | | 1, 2, 3 | Largest. 1 and 3 are "X" shaped (metacentric). 2 has a slightly lower centromere. | | B | 4, 5 | Large. Centromere is clearly in the upper third (submetacentric). 4 and 5 look nearly identical. | | C | 6, 7, 8, 9, 10, 11, 12, X | Medium. The largest group. X is indistinguishable from this group but usually placed near #7 or #8. | | D | 13, 14, 15 | Medium. Centromere is at the very top (acrocentric). They look like they have a "topknot." | | E | 16, 17, 18 | Short. 16 is clearly metacentric (middle pinched). 17 and 18 are slightly offset. | | F | 19, 20 | Small. Very small "X" shapes (metacentric). Difficult to tell 19 from 20. | | G | 21, 22, Y | Smallest. Acrocentric (top pinched). Y is generally slightly larger and more vertical than 21 or 22. | In a typical karyotype worksheet, students are presented