BIOL 1202 : Biology Notes Exam 4
Document Summary
Chapter 26: phylogeny and the tree of life. Prokaryotic cells have a variety of shapes: the three most common, sphere (cocci, rods (bacilli, spirals (spirilli) Cell-surface structures: cell wall, maintain cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment, composed of peptidoglycan in bacteria, may also have and outer phospholipid membrane. Cell surfaced structures: a capsule (sticky layer of polysaccharide or protein) may cover the cell wall of many prokaryotes, fimbriae and pilli allow prokaryotes to stick to their substrate or other individuals in a colony. Question: gram-negatuve bacteria have ____ peptidoglycan than gram-positive cells and their cell walls are ______ complex structurally. Motility: motile bacteria move by means of flagella, bacteria exhibit taxis, ability to move forward or away from certain stimuli, e. g. , positive chemotaxis- moving toward a chemical stimulus. Internal organization: prokaryotes do not have membrane-bound organelles, some do have specialized membranes that perform metabolic functions. Question: groups of staphylococcus aureus look like _______.
