Prokaryotes can live in extreme environment.
salt/ hot/ methane. they have cell walls for survival.
the cell wall keeps it from bursting (lyse) in a hypertonic environment. (water lost inhibits reproduction).
Cell walls are made of a mesh called Peptidoglycan (polysaccharides and peptides/proteins).
Peptidoglycan: thick layer (gram positive) cell turns purple. thin layer (gram negative) cell turns pink.
Pencillin makes holes in the cell walls, cause the cells to die.