Correct option is A
Ans. (a) A-ii; B-v; C-iii; D-i; E-iv
Sol. The correct pairings between Column X and Column Y are based on the treatments, reagents, and events used in human lymphocyte culture and chromosomal banding or karyotyping:
A-ii: 5% barium hydroxide treatment at 50°C is used to induce C-banding, which highlights the centromeric regions of chromosomes.
B-v: Trypsin treatment is commonly used in G-banding, which is a technique for visualizing chromosomes after staining.
C-iii: Phytohaemagglutinin (PHA) is used for mitotic stimulation, as it stimulates cell division, particularly for lymphocyte culture.
D-i: Phosphate buffer treatment at 80°C is used in R-banding, which is typically applied to visualize the chromosome’s bands in a reverse pattern compared to G-banding.
E-iv: Silver Staining is used for visualizing Nucleolar Organizer Regions (NOR) on chromosomes, which are associated with the production of ribosomal RNA.
Information Booster
C-banding (ii): This technique specifically stains the constitutive heterochromatin near the centromeres of chromosomes, resulting in a characteristic pattern that helps to identify certain chromosome features. It is achieved using barium hydroxide treatment.
G-banding (v): This is a widely used technique where chromosomes are stained with a dye such as Giemsa to produce a characteristic banding pattern. G-banding helps to visualize structural features of chromosomes and is important in karyotyping.
Mitotic stimulation (iii): Phytohaemagglutinin (PHA) stimulates lymphocytes to enter the mitotic phase, which is essential for obtaining chromosomes for banding and karyotyping.
R-banding (i): R-banding is essentially the reverse of G-banding. It stains the regions of the chromosome that are rich in guanine and cytosine, producing a different banding pattern.
Nucleolar Organizer Regions (NOR) (iv): Silver staining highlights the NORs in chromosomes, which are involved in ribosome production, essential for cell survival and growth.
