LAB REPORT : Looking at unusual Chromosomes

Name - Debojjal Bagchi SR N – 16849

Group - B

A) Observing Polytene Chromosomes in Drosophila melanogaster

Key to the labels in the diagram Sl. No. Legend Key Identification 1. a Chromocentre A region at which the centric region of polytene

chromosomes are joined together. (Common connection point)

2. b1, b2, b3, b4, b5 5 Chromosomal arms Thread like structures with bands.

3. c Asynapsis Asynapsis is the portion where two homologous polytene chromosomes fuse

4. d Chromosmal Puffs

Localised swelling of the chromosome

B) Observing Barr Bodies in Homo sapiens As pointed out (‘e’ in figure 2) we can see Barr Body in female epithelial cells from buccal cavity but not in male. It is not very distinct maybe because of improper staining.

Figure 1 :- Images of Polytene Squashes at 40x

Figure 2 : Female Buccal Smear Figure 3 : Male Buccal Smear