Mb 23.0 21.4 24.4 28.0 21.8 20.0 1.2 Mb 5.4 11.0 8.2 8.2 3.1 Chromosome 2 2R 3L
ID: 191163 • Letter: M
Question
Mb 23.0 21.4 24.4 28.0 21.8 20.0 1.2 Mb 5.4 11.0 8.2 8.2 3.1 Chromosome 2 2R 3L 3R 40.9 X and Y Heterochromatin Euchromatin O Centromere Fig. 1. Mitotic chromosomes of D. melanogaster, showing euchromatic regions, heterochromatic regions, and centromeres. Arms of the autosomes are designated 2L, 2R, 3, 3R, and 4. The euchromatic length in megabases is derived from the sequence analysis. The heterochromatic lengths are estimated from direct measurements of mitotic chromosome lengths (67). The heterochromatic block of the X chromosome is polymorphic among stocks and varies from one-third to one-half of the length of the mitotic chromosome. The Y chromesome is nearly entirely heterochromatic. H 2000 VOL 287 SCIENCE www.sciencemag.orgExplanation / Answer
answer- the image is about mitotic chromosome of D. melanogaster or common fruit fly. euchromatic and heterochromatic regions of the chromosome are depicted in white and grey colors, respectively. the euchromatic region is highly condensed and contains transcribed genes, whereas, heterochromatic regions are less active. the lengths of euchromatic and heterochromatic regions are depicted in the image and it is evident that Y chromosome of fruit fly have majorly heterochromatin, whereas, X chromosomes have both hetero- as well as euchromatin.