Chapter 27~ Prokaryotes and the Origins of Metabolic Diversity

Classification

Kingdom: Monera? Domain: Bacteria Domain: Archaea

Shape •cocci (sphere) •bacilli (rod) •helical (spiral)

Structural characteristics

Cell wall~ peptidoglycan (sugars & proteins); √ Gram +: w/peptidoglycan penicillin action √ Gram -: little peptidoglycan, lipopolysaccharides; most pathogens; impede drug action

Capsule: adherence; protection Pili: adherence; conjugation

Motility 1- Flagella 2- Helical shape (spirochetes) 4-Taxis (movement away or toward a

stimulus)

Form & Function Nucleoid region

(genophore: non-eukaryotic chromosome)

Plasmids Asexual

reproduction: binary fission (not mitosis)

“Sexual” reproduction (not meiosis): transformation~ uptake of genes from

surrounding environment conjugation~ direct gene transfer from 1 prokaryote to another transduction~ gene transfer by viruses

Endospore: resistant cells for harsh conditions (250 million years!)

Nutrition & Metabolism Photoautotrophs:

photosynthetic; harness light to drive the synthesis of organics (cyanobacteria)

Chemoautotrophs: oxidation of inorganics for energy; get carbon from CO2

Photoheterotrophs: use light to generate ATP but get carbon in an organic form

Chemoheterotrophs: consume organic molecules for both energy and carbon

saprobes- dead organic matter decomposers parasites- absorb nutrients from living hosts

Nitrogen fixation: conversion of atmospheric nitrogen (N2) to ammonium (NH4+)

Oxygen relationships: obligate aerobes; facultative anaerobes; obligate anaerobes

Prokaryotic ecology Decomposers: unlock organics from

corpses and waste products Symbiosis~

•symbiont/host •mutualism (+, +) •parasitism (+, -) •commensalism (+, 0)

Disease •opportunistic: normal residents of host; cause illness when defenses are weakened •Koch’s postulates: criteria for bacterial disease confirmation •exotoxins: bacterial proteins that can produce disease w/o the prokaryote present (botulism) •endotoxins: components of gram - membranes (Salmonella)