Molecular Biology 1-2 put together by: Linda Fahlberg-Stojanovska Disclaimer: I put these together for my kid for his smartphone. However, I found most images had very small type and increased the font size. I am posting it because another teacher might find this useful. The sources are given. If I have used anything illegally, write me and I will take it off. 1
Cell Structure, Cell Parts, Bacteria, Gram Positive Gram Negative, Viruses: The images have big font size and reduced background color. Useful for smartphones, classroom and printouts. The rest is standard stuff.
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Molecular Biology 1-2
put together by: Linda Fahlberg-Stojanovska
Disclaimer: I put these together for my kid for his smartphone.
However, I found most images had very small type and increased the font size. I am posting it because another teacher might find this useful.
The sources are given. If I have used anything illegally, write me and I will take it off.
– add Gram’s iodine solution to bind crystal violet in the cell
– rapid decolorization with alcohol or acetone
Gram-positive cells are stained deep purple.
– counterstain with safranin
Gram-negative cells are stained red.
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Bacteria – Gram Staining
28http://pathmicro.med.sc.edu/fox/culture.htm
Bacteria – Gram Staining
• Reagents of Gram Staining
– Crystal violet (primary stain)
– Gram's Iodine solution(mordant that fixes crystal violet to cell wall)
– Decolorizer (e.g. ethanol)
– Safranin (secondary stain)
– Water (preferably in a squirt bottle)
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Bacteria – Gram Staining
• How Gram Staining Works– 2. Gram's iodine solution (iodine and potassium iodide) is
added to form a complex between the crystal violet and iodine. This complex is a larger molecule than the original crystal violet stain and iodine and is insoluble in water.
– 3. decolorizer dehydrates the peptidoglycan layer, shrinking and tightening it. The large crystal violet-iodine complex is trapped in the thick peptidoglycan layer of Gram positive bacteria and stained.
– Conversely, the thin peptidoglycan layer of Gram negative cells cannot hold the crystal violet-iodine complex and the color (stain) is washed out and lost.
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Virus particles (virions) •genetic material (DNA or RNA segment)•capsid (protein coat that protects these genes) •envelope (of lipids) (some virions)