BIOL 102 Lecture 10: Chapter 27
20 Nov 2016
Department
Course
Professor
Document Summary
Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms. More in a handful of soil than the number of people who have ever lied. Divided into 2 domains: bacteria and archaea. Most prokaryotes are unicellular, but some species form colonies. Have variety of shapes and 3 most common are spheres (coccus/cocci), rods (bacillus, bacilli), and spirals. Important feature is cell wall, which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic enviro. Eukaryote cell walls are made of cellulose or chitin. Bacterial cell walls contain peptidoglycan: peptidoglycan= a network of sugar polymers cross-linked by polypeptides. Scientist use the gram stain to classify bacteria by cell wall composition. Gram-positive bacteria= have simpler cell walls w/ a large amount of peptidoglycan. Gram-negative bacteria= have less peptidoglycan and an outer membrane that can be toxic to us. Archaea contain polysaccharides and proteins but lack peptidoglycan: stain mostly gram-negative.
