BRAINCAKEGram Stain
All bacterial cell walls are made of peptidoglycan. Before staining bacteria are often colourless.
Gram positive bacteria have a thick net-like layer of peptidoglycan containing a substance called teichoic acid.
When crystal violet followed by iodine is applied, the crystal violet-iodine complex is trapped within the cell wall and is not washed away when the sample is dehydrated with alcohol.
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More in Components of Living Systems
- Development of Cell Theory
- The Light Microscope
- Preparing Samples
- Staining
- Acid-Fast Technique
- Magnification
- Resolution
- The Eyepiece Graticule
All 21 lessons in Components of Living Systems · All OCR AS-level Biology topics