Chapter 27 p

MMost abundant organisms on Earth AAble to grow in hot, cold, salty, acidic, or basic (alkaline) conditions 22 Types: AArchaea: “ancient” live in extreme environments similar to early Earth BBacteria: modern bacteria

MMost are beneficial or non-harmful PProvide vitamins to humans CCycle elements through biosphere (C) AAre decomposers (digest dead/decaying organisms) FForm symbiotic relationships w/ other prokaryotes & eukaryotes

MMostly unicellular MMay aggregate into groups called colonies SShapes: CCocci: sphere BBacilli: rod HHelices: spiral or corkscrew DDiameter = 1-5 μm

MMaintains shape, protects, prevents bursting SSusceptible to plasmolysis (shrinkage) BBacteria (not archaea) contain peptidoglycan GGram Stain: tests for peptido. Gram + = ↑ peptido.; stains purple Antibiotics will inhibit peptido. formation Gram - = ↓ peptido.; stains pink Cells have outer membrane of lipopolysaccharides Generally more toxic (outer membrane protects)

 Capsule: sticky substance outside cell wall  Aids in cell adhesion (colonies) & protects  Polysaccharide or protein  Fimbriae: numerous hair-like appendages used to attach to host cell  Pili: hold cells together  Sex Pilus: used on conjugation

FFlagella: long cellular appendage CComposed of: BBasal Apparatus (motor): uses chemiosmosis (H+ diffusion INTO cell) to turn the hook HHook: anchors filament to basal apparatus & turns FFilament: composed of long chain of flagellin protein UUnder outer layer of cell wall TTaxis: movement toward/away from stimulus i.e.: chemical, light, magnetic field, each other (colonies)

IInstead of organelles, have infolds of plasma membrane for metabolism NNucleoid Region: where DNA located 11 ring of ss DNA (“genophore”) Plasmids: smaller separate rings of DNA HHave smaller ribosomes; susceptible to antibiotics

BBinary Fission: asexual reproduction; can exchange DNA by: 11) Transformation: intake from environment 22) Conjugation: exchange between 2 cells 33) Transduction: w/ help of viruses MMutations are main source of genetic variation VVery fast reproduction → spread rapidly AAccelerated natural selection

PProkaryotic “growth” = multiplication 11-3 hours IInhibited by medium or accumulation of waste EEndospores: thick- coated resistant cells formed within bacterial cell RRequires ↑ ↑ temps to kill (120°C min.) MMay remain dormant & re-emerge

AAll species require energy & C source 11) Photoautotrophs: light + CO 2 ii.e.: cyanobacteria (also plants & algae) 22) Chemoautotrophs: chemical (H 2 S, NH 3, Fe 2 - ) + CO 2 ii.e.: Sulfolobus 33) Photoheterotrophs: light + organic nutrients rrare 44) Chemoheterotrophs: chemical + organic nutrients ii.e.: saprobes & parasites