G banding

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G-banding is technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes.^[1] The metaphase chromosomes are treated with trypsin (to partially digest the protein) and stained with Giemsa. Dark bands that take up the stain are strongly A,T rich (gene poor). The reverse of G-bands is obtained in R-banding. Banding can be used to identify chromosomal abnormalities, such as translocations, because there is a unique pattern of light and dark bands for each chromosome.^[2]

It is difficult to identify and group chromosomes based on simple staining because the uniform color of the structures makes it difficult to differentiate between the different chromosomes. Therefore, techniques like G-banding were developed that made 'bands' appear on the chromosomes. These bands were same in appearance on the homologous chromosomes, thus, identification became easier and more accurate. The acid/saline/giemsa protocol reveals G-bands.

See also

• Giemsa

References

1. ^ Speicher, Michael R. and Nigel P. Carter. "The New Cytogenetics: Blurring the Boundaries with Molecular Biology." Nature Reviews Genetics, Vol 6. Oct 2005.
2. ^ ibid.

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