Four common staining procedures used in chromosomal analysis. Most karyotypes are prepared using G-b

Four common staining procedures used in chromosomal analysis. Most karyotypes are prepared using G-banding. R-banding produces a pattern of bands that is the reverse of those in G-banded chromosomes.


Banding technique
G-banding — Treat metaphase
spreads with trypsin, an enzyme that
digests part of chromosomal protein.
Stain with Giemsa stain. Observe
banding pattern with light microscope.
Q-banding — Treat metaphase
spreads with the chemical
quinacrine mustard. Observe
fluorescent banding pattern with
a special ultraviolet light microscope.
R-banding — Heat metaphase
spreads at high temperatures to
achieve partial denaturation of
DNA. Stain with Giemsa stain.
Observe with light microscope.
C-banding — Chemically treat
metaphase spreads to extract
DNA from the arms but not the
centromeric regions of
chromosomes. Stain with Giemsa
stain and observe with light microscope.
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Appearance of chromosomes
17 Darkly stained G bands.
I> Bright fluorescent bands
upon exposure to ultraviolet
light; same as darkly stained
G bands.
17 Darkly stained R bands
correspond to light bands
in G-banded chromosomes.
Pattern is the reverse of
G-banding.
4/ Darkly stained C band
centromeric region of the
chromosome corresponds to
region of constitutive
heterochromatin.
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