Chapter 7, Problem 1Q

Why do gram-positive cells more than 24 hours old stain gram-negative?

Summary Introduction

To write:

The reason for iodide can be added before the primary stain in a gram strain.

Introduction:

Staining is a method that provides variance to the microscopic image for enhanced vision under the microscope. It is a method that is extensively used for the assessment of cells and tissue components. It is often used to draw attention to the microbial structures for viewing with the help of diverse microscopes.

Explanation of Solution

Gram staining:

It is a common method that is used to distinguish two large bacterial groups based on their dissimilar cell wall components. The Gram stain process differentiates between the Gram-positive and negative bacterial groups by coloring these cells violet or red.

Gram-negative bacteria:

It loses the crystal violet stain in the Gram staining method. It is a feature of bacteria which contain a cell wall made up of thin layer peptidoglycan.

Gram-positive bacteria:

These bacteria contain a very thick cell wall of peptidoglycan. These gram-positive bacteria hold the crystal violet dye.

The reason for the gram-positive cells that are more than 24 hours old can stain gram-negative:

Because in the older cells, the cell walls become degenerate and lose the purple dye.

Conclusion

In the older cells, the cell walls become degenerate and lose the purple dye.