Download File - Pomp

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: noneukaryotic
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)