Question

The banding pattern of chromosomes is suited by fluorescent dyes and this pattern remains constant for a particular chromosome. What pattern does a normal banding give?
A. Q-banding
B. G-banding
C. C-banding
D. All of the above

Answer 1

Chromosome banding is the alternating light and dark areas throughout the length of chromosome after staining it with a dye. A band is defined as the part of chromosome which is easily differentiable from its neighbouring segments by either appearing light or dark with the help of certain banding techniques.

Complete answer:
- Chromosomes show different patterns for different banding techniques and types of dye. Chromosomes stained with quinacrine mustard give alternating bands of light and dark variations are called Q-banding.
- When the chromosome is treated with the proteolytic enzyme trypsin followed by staining with Giemsa stain, such banding is called G-banding. The chromosome is stained on euchromatin, centromeric and heterochromatin regions.
- On staining chromosomes with Giemsa stains in alkaline medium, the chromosome is stained constitutively on heterochromatic regions. The process is called C-banding.
Hence, all of the above options are correct.

Note: The banding pattern distinguishes chromatic abnormalities and structural rearrangements such as translocations, deletions, inversions and insertions. A normal banding gives all of the three bandings namely, Q-banding, G-banding and C-banding.