BIO153H5 Study Guide - Final Guide: Decomposer, Heterocyst, Extremophile
Document Summary
Cell walls maintain shape, protects the cell and prevents it from bursing in hypotonic environments. Most bacterial cell walls are made up of pepidoglycan a polymer composed of modiied sugars cross-linked by short polypepides. Archaeal cells lack pepidoglycan, but contain other proteins and polysaccharides. Gram stain: bacterium are stained with crystal violet dye and iodine and then rinsed with alcohol and inally stained with a red dye such as safranin. >> gram posiive (purple) - have large amounts of pepidoglycan. >> gram negaive (pink) - less pepidoglycan and are more complex (lipid bilayer that is selecively permeable). A capsule (if dense and well deined)/slime layer (if less organized) is a sicky layer surrounding the cell wall made up of polysaccharides or protein. >> protect against dehydraion and host"s immune system. Fimbriae hair like appendages that help prokaryotes sick to their substrate or to one another.
