(Solved) Why are bacteria stained before viewing through a microscope?

Julia

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11 years ago

Why are bacteria stained before viewing through a microscope?

What are the advantages of the different shapes of bacteria to organisms?
What are the structural differences between Gram positive and Gram negative bacteria?
What is another method for classifying bacteria (other than shape or cell wall structure)?

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lenaclaire

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11 years ago

You stain specimens to show up different structures in them different proteins, starches, cellulose and fats in the cells absorb different dyes different ways. With the right dyes you can colour specific structures very effectively.
Gram negative bacteria usually have an extra outside layer on the cell wall.

Bacteria might also be classified as procaryote or eucaryote depending on whether they have a nucleus.

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smooch92

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fionacurley

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11 years ago

Advantages of the different shapes of bacteria to organisms:
I do not know of any direct benefit of a bacillus (rod) or coccus (sphere) shape. However, the spirilla/spirochete (corkscrew) shape allows the bacteria to be motile. These bacteria move through liquid by rotating their entire self.

Gram positive bacteria have a thick cell wall (made of peptidoglycan) outside their plasma membrane. This thick cell wall holds the purple crystal violet stain during a gram stain.

Gram negative bacteria have a think peptidoglycan cell wall in the periplasmic space between the cell membrane and the outer membrane. The outer membrane is composed of lipopolysaccharide (LPS) in most species. LPS is an endotoxin that induces an inflammatory response in your body.

Another method for classifying bacteria is genetic analysis. This is the most common method used in research. Shape and cell wall tell very little about the metabolism of a bacterium. By analyzing the genome, scientists can determine phylogenetic relationships between bacterial species and can discover which proteins certain species produce.

Less sophisticated classification methods include colony morphology, metabolic tests (such as succinate fermentation, oxidation of hydrogen peroxide, etc), generation time, natural bioluminescence or pigmentation (Vibrio vulnificus naturally 'glows' and Serratia marcescens is red), and antibiotic resistance.

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