Question

need an explanation of how the gram stain is used and why it works. (this is not the gram stain procedure, but rather, how the dyes and steps work together to show Gram positive and Gram negative cell wall types)

Answer 1

The Gram staining technique is based on the characteristics of cell wall of bacteria. Gram positive bacteria have cell wall made of peptidoglycan while gram negative bacteria have cell wall made of lipids.

So, when crystal violet and iodine is added, crystal violet iodine complex forms which gets adhered to peptiglycan layer and so gram Positive bacteria will appear purple in color. When decoloriser by acid alcohol, this complex gets degraded in gram negative bacteria. So, when counter stain like saffronin is added, it takes up the color of counter stain and appears pink.