What is the Giemsa staining of chromosomes? I got the question in my exam and wrote the following and I do not understand what is wrong in it: > Giemsa staining is a staining method to stain particularly malaria and other parasital diseases. G-bands occur because Giemsa stain consists of A,T rich material i.e. poor gene such that dark and white bands occur. Each chromosome has an unique reaction to Giemsa staining so G-bands occur. 0 points. I do not understand what's wrong with it, since in their comments about the same question in my first exam they wrote also the extra questions: **What are G-bands? How are they formed and why?** This time I answered the given things and got zero mark. Probably, the mistake was that I did not answer to the question in the scope of medical Biology in some way. However, I am not exactly sure what it is exactly. **How would you answer to the question when you know that the course was about medical biology?** Please, add the tag Giemsa.

Giemsa is not a particular methid to stain malaria or any other parasite. It stains DNA. As such, it can be used to stain any DNA-containing organism, or, in other words, any known cell.

Regarding its particular use in chromosomal banding, you can refer to many online resources, such as this one of the University of Washington:

> Chromosomes in metaphase can be identified using certain staining techniques, so called banding
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> (...)
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> G-bands are most commonly used. They take their name from the Giemsa dye, but can be produced with other dyes. In G-bands, the dark regions tend to be heterochromatic, late-replicating and AT rich. The bright regions tend to be euchromatic, early-replicating and GC rich.