-
-
Classification
of Bacteria and Archaea
- •Easy
- to distinguish the domains
- •Harder
- to classify by clades
- –Not
- many obvious structural differences
- –Determining
- evolutionary relatedness difficult (no fossils)
- •Generally
- grouped by:
- –Shape
- –Locomotion
- –Pigments
- –Colony-forming
- –Staining
- properties (Gram stain
-
•Current- classification based largely upon molecular comparisons between nucleotide
- sequences in RNA (usually
rRNA)
-
Prokaryote
Shapes
- •Cell
- walls of prokaryotes give them their shape
- •Most
- common are spherical (
coccus), rod (bacillus),- corkscrew or spiral
-
Features
of Prokaryotes
- •Motility
- •Colony
- forming (films)
- •Endospores
- •Occupy
- diverse habitats
- •Can
- be anaerobic
- •Most
- reproduce asexually
-
Prokaryote
Motility
- •Both
- bacteria and
archaea can- have flagella
- •May
- have one or many
- •Archaea have
- thinner flagella
- •Prokaryote
- flagella is different structurally from eukaryotes
-
Colonial
Prokaryotes
- •Slime
- on surface protects and/or helps with adhesion to surfaces or each other
-
Endospores
- •Genetic
- material and protein encapsulated
- •Prokaryotic
- cell breaks open
- •This
- resting spore will be ‘reactivated’ when conditions improve
-
Habitats of prokaryots
- •Virtually
- all habitats on earth contain prokaryotes
- •Extreme
- habitats, thought to be devoid of life, contain main specialized species
- –Deep
- sea
- –Boiling
- mud pots, glaciers
- –High
- salinity
- •Within
- the bodies of other organisms
-
Metabolism of prokaryots
- •Can
- be aerobic or anaerobic
- •Anaerobic-
- metabolic processes do not require oxygen
- –Obligate
- anaerobes
- –Facultative
- anaerobes
- •Some
- species can utilize “non-food” molecules
- –Hydrocarbons,
- methane, sulfur, etc.
- •Photosynthetic
- prokaryotes contain chlorophyll (ex:
cyanobacteria) - –
-
Reproduction of prokaryots
- •Binary
- fission- asexual reproduction by splitting
- –Rapid,
- permits rapid evolution, ability to successfully inhabit temporary habitats
- •Conjugation-
- sexual reproduction by exchange of plasmid through temporary binding of plasma
- membrane
-
Importance
of Prokaryotes
- •Produce
- nutrients
- –Vits K
- and B12
- •Break
- down food (herbivores)
- –Digest
- cellulose
- •Nitrogen
- cycle
- –Nitrogen
- fixation: converting inorganic N into organic N
- –Legumes
- have chamber of nitrogen fixing bacteria
- –N
- fixing bacteria also live in soil
- •Decomposition
- –Prokaryotes
- break down dead/decaying matter and recycle nutrients
- •Bioremediation
- –Using
- prokaryotes to break down waste products (hydrocarbons, industrial waste,
- detergents,
etc)
-
Disease of Prokaryots
- •Bacteria
- produce toxins (
tetnus) - •Cause
- sickness (Lyme disease, cholera, plague)
- •Common
- bacteria can be harmful depending upon situation and individual
-
Viruses Structure
- •Protein
- coat with DNA or RNA
- •Come
- in many shapes
- •Very
- small
- •
-
Virus
Lifestyle
- •Parasitic
- –Reproduce
- only in a host cell
- •Host-specific
- •May
- be cell-specific
- •Infections
- are difficult to treat without damaging host, viruses evolve quickly
-
Prions
and Viroids
- •Viroids-
- particles of RNA (no protein coat)
- –Infect
- mostly plants
- •Prions
- – protein particles that are infectious
- –BSE
- (‘mad cow’)
- –Creutzfeld-Jacob
- –Scrapie
- –Kuru
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