1 explain how the differences in cell wall structures of...

1. Explain how the differences in cell wall structures of gram-positive and gram-negative bacteria cause them to stain differently with the Gram stain. 2. Describe the purpose of each of the four basic steps of Gram staining. 3. Describe the images provided at the "Bacterial Morphology and Staining Techniques" web link for Staphylococcus epidermidis and Escherichia coli, including the color and morphology of each organism. 4. Discuss how the structure of gram-negative bacteria contributes to their ability to cause disease.

Transcript

00:01 Hello students, the question is we have to give the differences in staining of gram positive bacteria and gram negative bacteria.

00:12 If we see gram positive bacteria it has thick peptidoglycan layer, it retains crystal violet and iodine complex.

00:25 In case of gram negative bacteria the thinner peptidoglycan layers it has and the outer membrane contains lipopolysaccharide which in turn leads to the loss of crystal violet, iodine complex and uptake of the counter strain that is safranin.

00:45 If we see in gram positive bacteria the stain staining it appears purple, the bacteria it appears purple after staining and the gram negative bacteria it appears pink under the microscope after staining.

01:05 If we see we have asked the four basic gram staining steps.

01:10 The first step will be crystal violet.

01:15 The crystal violet step in this step there will be this, this is the primary stain and it binds to the peptidoglycan layer of both the gram positive and gram negative bacteria.

01:35 Next step will be iodine.

01:39 This moderate enhances the binding of crystal violet to the peptidoglycan layer the crystal forming a crystal violet iodine complex which is retained by only gram positive bacteria.

01:55 Next step is alcohol and acetone.

01:58 It is a decolorizing agent.

02:00 It removes the crystal violet iodine complex from the gram negative bacteria making them colorless.

02:10 Next will be safranin...

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