Question

Which of the following stains is not used for staining chromosomes?
A. Basic Fuchsin
B. Safranin
C. Methylene green
D. Carmine

Answer 1

Hint: Staining is responsible for the alternating dark and light bands on chromosomes. Banding can be used to identify chromosomal abnormalities; this is done because there is a unique pattern of dark and light bands for each chromosome.

Complete answer:
Basic Fuchsin is a stain which can be used to detect proteins in acidic pH systems. Basic Fuchsin is widely used in biology to stain nuclei. The Basic Fuchsin is a cationic dye used for fast detection of bacilli. Methylene green used to stain Golgi bodies, pectic substances and also nuclei. Carmine is the basic dye used to stain nucleic acid and chromosomes and gives them pink colour.
Safranin is used as counterstain in gram staining and endospore staining. Safranin can also be used for detection of cartilage and mast cell granules.
There are several other staining techniques used for more advanced purposes. One called Q-banding, stains chromosomes with quinacrine mustard and. The bright Q bands correspond almost exactly with the dark bands seen with Giemsa. A second method, called R-banding, treats chromosomes in such a way that the dark and light G bands are reversed. Third, and most recent, is the FISH (fluorescence in situ hybridization) technique. FISH deploys DNA probes specific for each chromosome (or sub chromosomal region or single locus).
The probes are labelled with modified nucleotides that fluoresce under particular conditions. By using different fluorochromes, a karyotype can be “painted” as desired. 24 different probes and fluorochromes produce a visually striking karyotype that has powerful uses in cytogenetics.
It allows, for instance, direct karyotyping of a metaphase spread without the laborious cutting and arranging process usually employed.

Hence, the correct answer is option (B)

Note: There are various stains that can bind to chromosomes and thus, can be used for chromosome staining. Each chromosome pair stains with its own characteristics banding pattern.