Which type of dye has a negatively charged chromogen?

The correct answer is that both basic dyes and anionic dyes have negatively charged chromogens. Basic dyes are characterized by their positively charged chromogens, which allows them to bind easily to negatively charged cellular components such as nucleic acids and proteins. In contrast, acidic dyes, which contain negatively charged chromogens, are used to stain the background rather than the cells.

Anionic dyes are a subset of acidic dyes, and since both categories include dyes that possess a negative charge, they bind to positively charged structures in the cell. This understanding helps to clarify the purposes and cellular interactions of different dye types in microbiological staining techniques.