BIOL 3380 Chapter Notes - Chapter 1: Hans Christian Gram, Crystal Violet, Safranin
Document Summary
Gram stain hans christian gram (1884: procedure, 1. Stain with crystal violet (cationic, interacts with anionic components of both. Gram pos and neg in bacteria: 2. Add iodine (complexed with crystal violet to form complexes: 3. Wash with alcohol gram negatives become decolorized and gram positives retain color: 4. Counterstain with safranin (red dye) gram negatives become red and gram positives remain purple: ** gram positive purple (ex. Staphylococcus aureus: gram negative red (ex. Escherichia coli: some bacteria don"t follow this paradigm, 1. Acid fast bacteria mycobacterium; contains waxes, hydrocarbons 60 to 90 carbons in length (mycolic acid); can be attached to pg impervious to harsh chemicals: 2. No cell walls mycoplasma; contains no pg delicate in culture but survives in human body: s layer protein or carb layer around cells; in eubacteria, often present along with other cell wall components. Capsule extracellular polymeric matrix can be polysaccharide, proteinaceous, or.
