MCB 3020C Lecture Notes - Lecture 3: Gliding Motility, Ultramicrobacteria, Gram Staining
Document Summary
Lecture 3: cell morphology and size of bacteria and archaea. Morphology: cell shape: coccus: spherical or ovoid, rod/ bacillus: cylindrical, spirillum: curved or spiral. Some stay grouped/clustered after cell division in characteristic arrangements. Morphology typically does not predict physiology, ecology, phylogeny, or other properties of a prokaryotic cell. Main function: selective permeability (nutrients transported in and waste products out) Bacterial cytoplasmic membrane: 8-10 nm wide, some species strengthened by hopanoids, embedded proteins including integral membrane proteins (significantly embedded) or peripheral membrane proteins (loosely attached) Species of bacteria separated into two groups based on gram stain. Gram-positives and gram-negatives have different cell wall structures: gram-negative cell wall (also called cell envelope, at least two layers, gram-positive cell wall, thicker, primary one layer of peptidoglycan. Few prokaryotes lack cell walls: mycoplasmas, group of pathogenic bacteria related to gram-positives, thermoplasma, archaea, have touch cytoplasmic membranes. Small amount of total cell wall contains peptidoglycan.
