BIO 3124 Lecture Notes - Lecture 4: Micrococcus, Clostridium, Mycobacterium
Document Summary
Interacts with negative groups (ie. plasma membrane is the most common target) Bacteria will be stained, background will not (stain specimen) Interacts with positive groups (ie. glass, the background) Background will be stained, bacteria will not: method: simple staining. Allows to determine the size, shape, and grouping of cells. Number of axes along which division occurs gives rise to different groupings. Typical of spirochetes: differential staining: gram staining. Gram staining divides bacteria into two groups as a function of the composition of the cell wall. Gram staining uses a combination of two stains: primary stain (crystal violet), and the secondary stain (safranin): gram negative: red. Cell wall does not allow primary stain to be trapped. Plasma membrane (lipids), thin cell wall (peptidoglycan), additional plasma membrane: gram positive: purple. Bio3124: method, staining with crystal violet (positive charge), add gram"s iodine (mordant), alcohol wash. Gram positive: cell wall is dehydrated and less permeable.
