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Bacteria
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Prokaryote
 Peptidoglycan
 Methanogen
 Halophile
 Thermoacidophile
 Bacillus
 Coccus
 Spirillum
 Streptococcus
 Staphylococcus
 Gram-negative
bacteria
 Gram-positive
bacteria
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A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
Rod-shaped bacteria
Spiral-shaped bacteria
Sphere-shaped bacteria
Clusters of sphere-shaped
bacteria
Chains of sphere-shaped
bacteria
“Salt-loving” archaea
“Heat-living” archaea
Anaerobic archaea
Protein-carbohydrate found
in bacterial cell walls
Appear reddish-pink when
dyed
Appear purple when dyed
Cells w/ no nucleus
Prokaryote
 Peptidoglycan
 Methanogen
 Halophile
 Thermoacidophile
 Bacillus
 Coccus
 Spirillum
 Streptococcus
 Staphylococcus
 Gram-negative bacteria
 Gram-positive bacteria
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L
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H
F
G
A
C
B
E
D
J
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Most numerous organisms
on Earth
 Found almost everywhere
 Fossils date back 3.5 bya
(first forms of life)
 Single cells with no nucleus
 Major source of food for
many organisms
 Important decomposers in
the environment
 Divided into two domains:
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Domain Archaea
Domain Bacteria
Notice that Archaea are
more closely related to
Eukarya than to Bacteria and
thus share a more recent
common ancestor.
 Archaea
= archaic (ancient)
 Differ from other prokaryotes in the following
ways:
Cell walls do not contain peptidoglycan
 Have introns (portions of DNA that do not code for
proteins)
 Live in extreme environments
 Different lipids in cell membranes
 rRNA resembles rRNA of eukaryotes
 Genes resemble genes of eukaryotes

 Methanogens:
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Convert hydrogen gas
and carbon dioxide into
methane gas.
Anaerobic
Live in muddy swamps,
sewers, intestines of
cows and termites
http://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Arkea.jpg/220px-Arkea.jpg
 Halophiles:


“Salt-loving” archaea
Live in very high salt concentrations (Great Salt Lake
and the Dead Sea)
Owens Lake in CA.
The lake became
extremely salty when
the Owens river
was diverted to supply
water to LA. PPG
operated a soda ash
plant (seen in the
background)
for making glass. The
color is due to the
millions of halophiles
that now live in the lake
 Thermoacidophiles:


Live in acid environments (pH <2) with very high
temperatures (>230 degrees F).
Ex: Hot sulfur springs of Yellowstone National
Park; deep water thermal vents (black smokers)
 Unlike
archaea,
members of the
domain bacteria:
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Have cell walls with
peptidoglycan
Have no introns
Live in a wide variety of
environments
Have lipid membranes
rRNA is unlike rRNA of
eukaryotes
Genes are unlike
eukaryotes genes
 Bacteria
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come in a few basic shapes:
Bacilli (rod-shaped): streptobacilli (chains)
Cocci (sphere-shaped):streptococci (chains):
staphylococci (clusters)
Spirilla (spiral-shaped)
Spirochaete (corkscrew)
Vibrio (comma-shaped)

A staining technique called the gram stain illustrates a
fundamental difference between two categories of bacteria:
the gram positive and the gram negative bacteria.
 Gram negative have complex cells walls with little
peptidoglycan. They stain a reddish color.
 Gram positive have simpler cell walls with a lot of
peptidoglycan. They stain a purple color.
 Classifying
bacteria based on evolutionary
relationships has been difficult because
bacteria can pick up genes from their
environment through transformation.
 Most scientists recognize the following
groups:

Proteobacteria:
 Very large and diverse group
 Include: nitrogen-fixing bacteria that live in
nodules inside the roots of legumes (peas,
beans, alfalfa, and clover). These bacteria
convert atmospheric nitrogen to ammonia,
which plants can use.
 Also includes some disease-causing bacteria
such as rickettsia bacteria (causes Rocky
Mountain Spotted Fever) and helicobacter
pylori (causes stomach ulcers)
 Also includes enteric bacteria (symbiotic
bacteria that live in intestinal tracts of
humans and animals)Ex: E. coli lives in our
intestines and secretes vitamin K as well as
assisting in the digestive breakdown of foods.
 Other strands of E.coli and Salmonella cause
food poisoning.
E.coli bacteria
Gram-positive bacteria: will
stain purple when gram stain
is applied.
 Examples include:
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Streptococcus: causes strep
throat
Clostridium botulinum: causes
botulism also used in botox
injections
Lactobacilli: sours milk; used in
yogurt
Bacillus anthracis: causes
anthrax
Actinomycetes: soil bacteria
used to make many antibiotics
 Cyanobacteria:
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photosynthetic bacteria
Earth’s first oxygen-producing organisms and
are believed to be responsible for transforming
Earth’s early atmosphere
Some grow in long filaments
Some form specialized cells called heterocysts
which can fix nitrogen
 Spirochetes
are gram-negative spiral-shaped
bacteria.

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Move with a corkscrew rotation
Can be free living or pathogenic
Ex: Treponema pallidum: causes syphilis
Borrelia burgdorferi: causes Lyme disease
Chlamydia are gram-negative bacteria that live
only inside animal cells.
 There cell walls lack peptidoglycan
 Ex: Chlamydia trachomatis: causes chlamydia
(sexually transmitted disease) and trachoma eye
disease, a leading cause of blindness.

Bacteria are the purple dots
inside a cell (pinkish brown)
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Plasmid
Capsule
Glycocalyx
Pilus
Endospore
Heterotroph
Autotroph
Phototroph
Chemotroph
Obligate anaerobe
Facultative anaerobe
Obligate aerobe
Transformation
Conjugation
Tranduction
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
M.
N.
O.
Sticky sugars found in bacterial
capsules
Structure formed to survive harsh
environmental conditions
Short, hair-like projection
One bacteria transfers DNA to another
Bacteria takes in DNA from its outside
environment
Virus introduces DNA from one
bacteria to another
Small, circular loop of DNA
Outer polysaccharide covering
Obtain carbon from CO2
Obtain carbon from other organisms
Get energy from light
Get energy from chemicals
Can live with or without oxygen
Must have oxygen
Must live without oxygen
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Plasmid
Capsule
Glycocalyx
Pilus
Endospore
Heterotroph
Autotroph
Phototroph
Chemotroph
Obligate anaerobe
Facultative anaerobe
Obligate aerobe
Transformation
Conjugation
Tranduction
G
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A
C
B
J
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L
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M
N
E
D
F

General prokaryotic
structure includes:
 Capsule
 Cell wall
 Cell membrane
 Cytoplasm
 Ribosomes
 DNA (nucleoid
region)
 Pili
 Flagella

Cell wall
Provides shape and protection
 Made of peptidoglycan and lipopolysaccharides (only
on gram negative)
 Many antibiotics are designed to kill bacteria by
breaking down the peptidoglycans of their cell walls.
They are most effective on gram positive bacteria.

 Also
called the plasma membrane, the cell
membrane controls what gets in or out of the
bacteria cell.
 Consists of a lipid bilayer and proteins
 Contains catalytic enzymes for respiration
and photosynthesis
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DNA of prokaryotes consists
of a single closed loop of
double-stranded DNA
Located in a central area
called the nucleoid region
Most bacteria also have
small rings of DNA called
plasmids
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Self-replicate
Not necessary for cell
survival
Often carry genes that allow
bacteria to cause disease
Often carry genes that
provide bacteria to become
resistant to antibiotics
 Many
bacteria have an outer covering of
polysaccharides called a capsule
 Their function:
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Protection from drying out
Protection from phagocytic white blood cells
Fuzzy glycocalyx capsules allow bacteria to
connect to host cells and tissues (often appears as a
“halo” around stained bacteria cells
 Pili
are short, hairlike projections that help
bacteria connect to each other and to host
cells and other surfaces.
 Can serve as a bridge to pass genetic
material
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Endospores form in gram-positive
bacteria when environmental
conditions become harsh.
They can resist high temps, strong
chemicals, radiation, and drying
out.
Cell copies its DNA and then forms a
thick, protective covering around
this copy. Most of the water is
removed and the endospore
becomes metabolically inactive.
The rest of the cell will die, but the
endospore, with its DNA cargo can
remain viable for centuries.
It will reactivate when
environmental conditions become
favorable.
Can only be killed if heated to very
high temperatures under pressure.
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Some move by flagella
Movement toward or away from a stimulus is called taxis
Chemotaxis =response to chemical stimuli such as food or
toxins.
 Phototaxis =response to light
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http://www.youtube.com/watch?v=6p9e0oolbmE
 Two
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Source of carbon
Source of energy
 Two
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ways to obtain the carbon source:
Heterotrophs: obtain carbon from other
organisms
Autotrophs: obtain carbon from CO2
 Two

basic needs exist for prokaryotes:
ways to obtain the energy source:
Phototrophs: obtain energy from light
Chemotrophs: obtain energy from chemicals
 These
needs can be used to divide
prokaryotes into four nutritional groups:
Nutritional Mode
Energy and Carbon Source
Heterotroph
Photoheterotroph
Uses light energy but gets its
carbon from other organisms
Chemoheterotroph
Obtains both energy and carbon
from other organisms
Autotroph
Photoautotroph
Uses light energy and gets
carbon from CO2
Chemoautotroph
Extracts energy from inorganic
compounds and uses CO2 as a
carbon source
 Habitats
occupied are based on biochemical
abilities of different types of bacteria.
 Oxygen requirements:
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Obligate anaerobes cannot live in the presence
of oxygen. Ex: Clostridium tetani
Facultative anaerobes can live with or without
oxygen. Ex: E.coli
Obligate aerobes require oxygen to live.
Ex: Mycobacteriaum tuberculosis
 Temperature
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requirements:
Psychrophilic prokaryotes: “cold-loving” grow well in
32-68oF. Can survive Antarctic temps by growing under
the surface of rocks.
Mesophilic prokaryotes: grow well in moderate
temperatures between 68-104oF.
Thermophilic prokaryotes: grow well in very hot
temperatures between 113-230oF.
 pH
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requirements:
Most bacteria thrive in pHs between 6.5 and 7.5
Acidophiles are bacteria that thrive in low pHs
(below 6)
 Usually
reproduce by
binary fission
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Asexual reproduction
DNA duplicates
DNA molecules move to
poles
Cell divides
Two identical daughter
cells are formed
 Recombination
occurs when prokaryotes
exchange pieces of DNA without reproduction.
 Three ways recombination can occur:
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Transformation —a prokaryote takes DNA from its
outside environment.
Conjugation —two prokaryotes bind together and
one cell transfers DNA to the other through a sex
pilus.
Transduction —viruses transfer pieces of one
prokaryotes DNA to another
 Transformation
often involves
plasmids and
restriction
enzymes
 Conjugation
involves something called the
F factor to be present in the donor cell.

Transduction involves defective bacteriophages
that carry host DNA instead of viral DNA.
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Pathology
Exotoxin
Endotoxin
Antibiotic
resistance
Zoonosis
Bioremediation
A.
B.
C.
D.
E.
F.
Toxic substances made from
lipids and carbs that are
released after the cell dies.
Toxic substances secreted by
bacteria into their
environment
Evolution of pathogenic
bacteria that antibiotics
cannot kill
Study of diseases
A disease that can pass from
animal to humans
Using bacteria to recycle
compounds in nature
 Pathology
 Exotoxin
 Endotoxin
 Antibiotic
resistance
 Zoonosis
 Bioremediation
D
B
A
C
E
F
 Roles
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of bacteria:
Cause disease
Food production
Nitrogen fixation
Decomposers
Bioremediation
 Pathology
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—study of diseases
Pathogens: disease causing agents
Some bacteria cause disease by destroying body
tissues. Ex: Streptococcus
Some bacteria cause disease by secreting toxins:
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Exotoxins —toxins secreted by bacteria into their
environment. Ex: Clostridium tetani secretes toxins
that cause tetanus
Endotoxins —toxins released after the bacteria cell
dies. They can cause fever, body aches, diarrhea,
hemorrhage and weakness. Ex: E. coli
 Antibiotics
are substances used to kill
bacteria.
 Made naturally by some fungi and bacteria
 Kill neighboring bacteria or fungi that
compete for resources
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Some (Penicillin) interfere with the formation of
cell walls by breaking down peptidoglycans
Some (Tetracycline) interfere with protein
synthesis
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Antibiotic resistance is
the evolution of
populations of pathogenic
bacteria that antibiotics
are unable to kill.
Because of overprescription of
antibiotics, many
resistant genes are now
on R-plasmids which can
easily pass from one
bacteria to the next by
transformation.
This leads to multiple
resistances to many
antibiotics… Superbugs!
 Most
emerging diseases develop when
infectious agents, such as bacteria, pass from
wild animals to humans
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Zoonosis —a disease that can pass from animal to
human
Zoonotic disease are on the rise due to:
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Human population growth
Global travel and trade
 Foodborne
illnesses result from the improper
preparation, handling or storage of food.
 To avoid:
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Wash all raw fruits and vegetables
Wash hands and all utensils during food
preparation
Refrigerate raw foods (eggs and lunchmeats)
Cook meat thoroughly
Refrigerate leftovers promptly
 Several
methods can be used to prevent food
spoilage by bacteria:
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Foods can be dried and salted: Sausages and
hams
Refrigeration: Milk and eggs
Adding large amounts of sugar: Jellies and jams
Pickling adds acids which slow bacterial growth:
Pickles and relishes
Cooking at high temps: Meat products
Sealing and canning: canned foods
Adding preservatives: bread, juice and fruits

Used in food production:
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Buttermilk, sour cream, yogurt,
cheeses, sauerkraut, pickles, coffee,
and soy sauce
Used in chemical production:

Acetone, acetic acid, enzymes,
antibiotics and insulin
Used to help break down sewage
and added to laundry detergent to
dissolve stains
 Used in some pesticides
 Used in bioremediation to
breakdown pollutants
 Used in recombinant DNA
technology
