Gram Staining Experiment

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Introduction Gram staining is a method commonly used to determine the chemical make up of the cell wall of bacteria. The cell wall can stain either positive or negative, depending on its chemistry.The aim of this experiment. Gram staining was the first differential technique used and still in use to make microscopic vision of bacteria clearer while also sub-divides the bacteria into two major groups: Gram-positive and Gram –negative. This experiment should help us describe how Gram staining affects the different cell walls of the different types of bacteria, based on their structural and biochemical differences. Different bacteria have different cell walls that react differently to the staining and de-colourisation procedure of Gram staining. …show more content…
If the bacteria stains positive it will retain a purple/blue color. If the bacteria stains negative, the bacteria will not retain the purple/blue color, but rather have a pinkish/red color.This method can also be useful in detecting pathogens from suspected specimens that need testing. The dyes used are not only used for Gram staining but extensively used to highlight structure of many biological specimens such as tissues and cells. Gram staining was developed in Berlin, in 1884, by the Danish scientist Hans Christian Joachim Gram. He studied at the University of Copenhagen where here turned as a Professor of Medicine. Gram staining is based on the ability of the bacteria's cell wall to retain the stain colour. Gram-negative bacteria do not have the ability to keep the stain colour of Crystal Violet and Gram's Iodide when washed with alcohol, while the Gram-positive bacteria, when washed with alcohol, causes their cell wall to shrink and traps the stain colour and therefore remains purple. Gram-negative bacteria are finally stained with or Safranine and that is how they obtain a pink …show more content…
If the bacteria stains negative, the bacteria will not retain the purple/blue color, but rather have a pinkish/red color. From my result in Fig 1 below, under the microscope,the bacteria stain positive and retain a purple/blue color. Fig. 1.Gram-positive bacteria appeared purple/blue color under the microscope. A typically gram positive reaction exhibited by Staphylococcus aureus. These organisms characteristically retain the primary dye, usually crystal violet,and appear dark purple in colour.

DISCUSSION All bacteria's cell wall contain peptidoglycan (murein), a molecule unique to bacteria.The cell wall of Gram-positive bacteria is made up of peptidoglycan (murein), a periplasmic space and an inner plasma membrane. The cell walls of Gram-positive bacteria binds with the Crystal Violet stain and thus they become purple.Gram-negative bacteria have many thin layers consisting of an outer membrane made of lipopolysaccharides and protein, periplasmic space, peptidoglycan and aninner plasma membrane. Lipopolysaccharides (LPS) is an endotoxin and can be harmful to organisms infected with Gram-negative bacteria . This outer layer of Lipopolysaccharides is dissolved by the alcohol during Gram staining so the cell wall loose the dye like the Crystal Violet ( 3

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