the Gram stain
In your next practical you will be characterising bacterial mixtures . One technique you will be using to do this is the Gram stain . Here is the Gram stain explained: The Gram stain differentiates between two major groups of bacteria based on their cell wall structure. So lets take a look at the two types of cell wall structure we are talking about... As you can see from the above diagram, Gram-positive bacteria have a thick peptidoglycan layer surrounding the membrane. Gram-negative bacteria on the other hand have a much thinner peptidoglycan layer and in addition they have another membrane surrounding this peptidoglycan layer. The Gram stain differentiates between these bacteria - hence they are called Gram positive and Gram negative depending on what they look like after being treated by the Gram staining procedure. What happens du...