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Prokaryotes:
Archaea & Bacteria
The Tree of Life
All
living things
classified in three
domains:
Bacteria
Archaea
Eukarya
Amazing Living Things
Microbes
important to all life:
Decomposition
Over half of Earth’s
More
biomass
bacterial cells than human cells in
your body!
Prokaryotes

Prokaryotes have:
 DNA
or RNA, ribosomes, cytoplasm, plasma
membrane
 Most prokaryotes have a cell wall, a capsule
(around the cell wall) and a flagellum

Prokaryotes don’t have:
 Organelles
such as nucleus, chloroplasts,
mitochondria.
Generalized Prokaryote
Nucleoid DNA
Plasmid DNA
Cytosol
Flagellum
Capsule
Plasma
Membrane
Cell Wall
Bacteria/Archaea

Habitats (name a place, and they live
there!)
 They
are specialists
 human
skin, mouth, respiratory tract, large
intestine, urogenital tract, etc.
 salty
Dead Sea
 extreme
 archea
 Aerobes
pH
in deep sea vents: 90-106o C
and anaerobes
Some Prokaryotes Thrive in Extreme Conditions
Cyanobacteria in Yellowstone
Hot Springs
Archaea
Unique
lipid membranes, cell walls, and
RNA
EXTREME Environments:
Swamps,
hot springs, vent communities, cow
stomachs
concentrated salt environments
hot, acidic environments
Bacteria
Shape:
Cocci
- round
Bacilli - rod
Spirilla - spirals
Three Common Bacterial Shapes
(b)
(a)
(c)
bacillus
cocci
spirillus
The Prokaryote Flagellum
Flagella
Bacterium
Bacteria
 Reproduction
 Reproduction
is asexual, by simple
splitting (binary fission)
 Daughter
cells are genetic clones of
the parent cell
Binary Fission
DNA
Benefits of Bacteria

Symbiosis (mutualism)
 Ruminants’
digestive tracts
 Nitrogen fixing in soil, nodules on certain legumes
 Bacteria on/in the human body: intestines and vitamin K
and B12



Biodegradation - oil
Food production - cheese, yogurt, sauerkraut
Decomposers
Our Relationship With Bacteria
Harmful Bacteria


Some cause disease = pathogenic
In humans:
 Strep throat
 Toxins - tetanus, botulism
 Pneumonia
 "Flesh-eating" bacteria
 Plague
 Tuberculosis
 Cholera
 Lyme disease
ANTIBIOTICS= anti bacterial!!!
The Causes of Tooth Decay
Transmission of Bacterial
Pathogens
Airborne
 Water
 Food
 Direct (skin contact, blood, and other body
fluids)
 Insects and other hosts such as deer tick
(Lyme).

Germ Theory of Disease
Theory that microorganisms are the cause
of disease.
 1859 – Louis Pasteur

 Credited
with the idea that human diseases
were caused by bacteria and viruses (germ
theory)
 Very important discovery in the field of
medicine
 Also created vaccinations to prevent disease
Infectious Diseases

Average age of death, in first world
countries, jumped 30+ years in last century
 due
to antibiotics
 enhanced hygiene and nutrition

Antibiotic-resistant infections on the rise in
hospitals in the U.S.
 This
is due to bacterial evolution in response
to widespread use of antibiotics!