Depolarizationof the axon hillock to threshold results in the generationand propagation of an action potential. The action poten-tial is a transient change in the membrane potential charac-terized by a gradual depolarization to threshold, a rapid ris-ing phase, an overshoot, and a repolarization phase.
Ecology. Staphylococcus aureus is a normal inhabitant of the skin and mucous membranes in the nose of a healthy human, while S. epidermidis inhabits only the skin of healthy humans. S. aureus is infectious to both animals and humans.he Staphylococcus aureus genome, which is the most common species amoung the genome projects, is about 2.8 Mega-base pairs long with approximately 2,600 open reading frames, comprising 84.5% of the genome.
Colonies formed by S. aureus are yellow (thus the name aureus, Latin for gold) and grow large on a rich medium. Staphylococcus aureus and their genus Staphylococci are facultative anaerobes which means they grow by aerobic respiration or fermentation that produces lactic acid.RSA (Methicillin-Resistant Staphylococcus aureus), which is resistant to the antibiotic methicillin, expresses a modified penicillin-binding protein encoded by mecA gene. This was brought about by many evolutions thought horizontal gene transfer of mecA to a wide variety of methicillin susceptible S. aureus strains.