Example of structure or substance in living cell that represented by methylene blue?

Methylene blue is a dye that binds to cellular components, particularly nucleic acids and proteins. In living cells, it can highlight structures such as the nucleus, where DNA is concentrated, and other organelles like mitochondria. This staining allows for visualization of cellular morphology and can help identify living versus dead cells, as viable cells typically take up the dye differently than non-viable ones.