Question

Are prokaryotes gram-positive or gram-negative?

Answer 1

Gram-positive:

1. Bacteria that retain the crystal violet color and stain purple are Gram-positive bacteria.
2. They have a thicker cell wall due to multiple thick peptidoglycan layers.
3. Peptidoglycan layers retain the stain after the decolorization step.
4. They usually produce exotoxins.
5. Example- Streptococcus, Staphylococcus, etc.
6. Gram-positive prokaryotes: Actinomyces, Corynebacterium, Mycobacterium, etc.

Gram-negative:

1. Bacteria that lose crystal violet & stain red are Gram-negative bacteria.
2. They lack an outer membrane & have a thinner cell wall.
3. It is composed of thin peptidoglycan layers.
4. They generally produce endotoxins.
5. Gram-negative prokaryotes- Salmonella, Escherichia, etc.
6. Thus, prokaryotes can either be gram-positive or gram-negative.