Lecture #12
Date ________
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Chapter 27~
Prokaryotes and
the Origins of
Metabolic Diversity
Classification
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Kingdom: Monera?
Domain: Bacteria
Domain: Archaea
Shape
•cocci (sphere)
•bacilli (rod)
•helical (spiral)
Structural characteristics
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Cell wall~ peptidoglycan
(sugars & proteins);
√ Gram +: w/peptidoglycan
penicillin action
√ Gram -: little peptidoglycan,
lipopolysaccharides; most
pathogens; impede drug action
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Capsule: adherence; protection
Pili: adherence; conjugation
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Motility
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1- Flagella
2- Helical shape
(spirochetes)
3- Slime
4-Taxis
(movement away or
toward a
stimulus)
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Form & Function
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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
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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
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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)