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)

3- Slime

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)

Koch’s Postulates

The bacteria must be present in every case of the disease.

The bacteria must be isolated from the host with the disease and grown in pure culture.

The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.

The bacteria must be recoverable from the experimentally infected host.

Bioremediation

Decompose sewage

Decompose petroleum products in spills

Decompose pesticides

Chemical “factories”

Acetone, butanol

Vitamins, antibiotics, insulin

Yogurt, cheese

Used in magnetic tapes ? ? ? ?