#AP Biology #AP Bio #Biology #Study Guide #campbell

CAMPBELL BIOLOGY, AP* 9th EDITION Chapter 27: Bacteria and Archaea 27.1 first organisms were likely prokaryotes unicellular variety of shapes - spherical, rod-shaped, and spiral well-organized the cell wall keeps it from bursting in a hypotonic solution and supports structure in hypertonic solutions, they shrink away from walls/plasmolyze contain peptidoglycan - polymer made of modified sugars crosslinked by short polypeptides. Archaea lack peptidoglycan but bacteria have it. Using the a technique called the Gram stain, scientists classify bacterial species into two ?groups based on cell wall composition Gram positive - simpler walls and a large amount of peptidoglycan Gram negative - less peptidoglycan and more structurally complex. Has an outer lipopolysaccharide membrane