- Column X and Y of the following table list some treatment methods, reagents, and events that are related to human lymphocyte culture, and banding/ karyotyping of human chromosomes.
Which one of the following options represents all correct matches between Column X and Column Y?
(1) A-ii; B-v; C-iii; D-i; E-iv
(2) A-v; B-iii; C-ii; D-iv; E-i
(3) A-iv; B-v; C-i; D-iii; E-ii
(4) A-ii; B-v; C-iv; D-i; E-iii
Column Y (reagents/events)
A. 5% barium hydroxide at 50°C
B. Trypsin treatment
C. Phytohaemagglutinin
D. Phosphate buffer treatment at 80°C
E. Silver staining
Column X (what they are used for)
i. R-banding
ii. C-banding
iii. Mitotic stimulation
iv. Nucleolar organizer region (NOR)
v. G-banding
Correct matches
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A → ii (C-banding)
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C-bands highlight constitutive heterochromatin, typically after barium hydroxide denaturation followed by Giemsa stain.
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B → v (G-banding)
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G-bands are produced by trypsin digestion of chromosomal proteins followed by Giemsa staining, revealing a characteristic light/dark banding pattern.
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C → iii (Mitotic stimulation)
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Phytohaemagglutinin (PHA) is a plant lectin that stimulates resting human lymphocytes to enter mitosis, providing metaphase chromosomes for karyotyping.
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D → i (R-banding)
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R-bands (reverse bands), which are the inverse of G-bands, are generated by heat treatment (e.g., phosphate buffer at high temperature ~80°C) followed by staining.
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E → iv (NOR)
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Silver staining (Ag-NOR) specifically highlights nucleolar organizer regions, the active rRNA gene clusters on acrocentric chromosomes.
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Thus the complete correct combination is:
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A–ii, B–v, C–iii, D–i, E–iv → option (4).
