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Bacteria
Chapter 24
Introduction
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Believed to be the oldest form of life
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Fossil evidence dates bacteria to 3.5 bya
Can live in all environments on earth
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Deep ocean vents (archae)
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Extremely salty environments (archae)
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Great salt lake, dead sea
Swamps/digestive tract (archae)
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High temp, high pressure, highly acidic
Produce methane gas
Others surround us at all times (bacteria/eubacteria)
Billions on your body at all time
Classification
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Broken into 5/6 kingdoms
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Monera = archaebacteria and eubacteria
Microbiology uses 3 domains
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Archae, bacteria, eukarya
Kingdom
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All bacteria are considered Monera
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Includes bacteria and blue-green algae
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Archaebacteria (Domain Archaea)
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Blue-green algae also called cyanobacteria
“Ancient” bacteria
First broken off in 1977
Eubacteria (Domain Bacteria)
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“Modern” bacteria
Prokaryotes
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Lack membrane bound
organelles
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No membrane organelles =
no nucleus
Single circular strand of
DNA
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Makes replication,
transcription, translation
occur much more rapidly
Unicellular
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All bacteria are unicellular
All prokaryotes are bacteria= all
prokaryotes are unicellular
Not all unicellular are prokaryotes
Phyla
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Schizophyta: common bacteria
Cyanophyta: Blue green algae
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Responsible for formation of current
atmosphere
More Classification
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Bacteria classification in large part determined
by gram staining
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Gram positive have a thick cell wall that absorbs
purple dye
Gram negative have a thin cell wall, do not absorb
dye and appear pink
Knowing if bacteria is gram +/- is important because
of different succeptibilities to antibacterial drugs and
disinfectants
Also release different toxins
Very useful tool tool for grouping bacteria
Linnaeus’s System of Classification
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Due to enormous number of living things
of all types a classification system was
devised by a Swedish naturalist named
Carrolus Linnaeus (1707-1778)
Used organisms morphology (structure
and form) to categorize it
Example of Levels of Classification
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Level
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Example
Animalia
Chordata
Mammalia
Carnivora
Felidae
Panthera
Leo (Panthera Leo)
Binomial Nomenclature
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Scientific name of each organisms consist of 2
parts
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Genus and species
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Examples
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Genus written first
Species written second
Homo (genus) sapien (species), panthera (genus) leo
(species), panthera (genus) tigris (species)
Members of the same genus share many
morphological similarities
Methods of Getting Food
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Heterotrophic
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Unable to make organic molecules from inorganic
molecules
Saprophytic bacteria
Autotrophic
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Organisms that can make organic molecules for food
Chemosynthetic
Photosynthetic
Types of Reproduction/Genetic
Variation/Survival Adaptations
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Binary Fission
Endospores
Conjugation
Transformation
Transduction
Binary Fission
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Simplest form of
asexual reproduction
Parent cell split into
two new cells
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Offspring are exact
copies
Very rapid
Endospores
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Help bacteria survive
harsh conditions
Used by some gram
positive bacteria
Protects the genetic
information
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Thick covering that is
over the genetic info
Cell may die, but
endospore can survive
Transformation
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DNA from dead bacteria is taken in by
living bacteria
Living bacteria may take on traits of the
dead ones
Major experiment done by Frederick
Griffith (1928)
Griffith’s Experiment
Conjugation
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Bacteria join
and transfer
genetic
information
Transduction
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Virus transfers material between 2
bacterial cells
Size of Bacterial Cells
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Very small
Simple cells, do not require much material
Cell size measured in microns
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Also called micrometer
mm
1 micron = 1/1 000 000 m
1 000 000 micron = 1m
Size Scale
Shape: Coccus (KOK-us)
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Round or
spherical
Plural term is
cocci
Shape: Bacillus (buh-SILL-us)
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Rod shaped
Plural is
bacilli
Some are
curved
(comma
shape) called
vibrio
Shape: Spirillum (spy-RILL-um)
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Spiral shaped
Plural is spirilla
Also called
spirochetes
Prefix: Diplo
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2
2 cells linked together
Prefix: Strepto- (STREP-toh)
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Twisted/chain
Many cells
Prefix: Staphyl- (STAH-fill-oh)
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Cluster/bunch
Structure of Bacterial Cells
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All have
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Rigid cell walls
Capsule – structure that surrounds cell wall
Genetic material- looks like a tangled bundle in the
nuclear area
Some have
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Plasmids-extra genetic information
1 or more flagella- tail for movement (motile)
Pili – tiny hairs used for attachment
Respiration: Aerobic
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Process that requires oxygen to break
down glucose
These bacteria are similar to mitochondria
Referred to as obligate aerobes
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Must have oxygen gas available
Respiration: Anaerobic
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Energy produced without oxygen
Similar to the anaerobic process discussed
earlier
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Obligate anaerobes cannot be exposed to
oxygen
Oxygen gas is actually a poison for them
Respiration: Facultative Anaerobic
Bacteria
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Can live in both types of conditions
Do not use oxygen gas for energy
production
Oxygen gas is not a poison for them
however
E. Coli is an example of this
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Lives in digestive tract (No O2)
Lives outside the digestive tract (21% O2)
Life Style
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Most Bacteria are…
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Heterotrophic (very few autotrophic)
Saprophytic-live on dead organic material
Some bacteria are…
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Parasites
In a symbiotic relationship: close association
between 2 dissimilar organisms
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Mutualism: both bacteria and host benefit
Classified According To:
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Size/shape
Structure of cell wall
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Gram +/-
Whether or not they need oxygen
How they obtain food
More Terms
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Virulence – the ability to cause serious disease
Fermentation – production of alcohol/lactic acid
Pasteurization – a way to inhibit bacterial growth
in some foods
Clostridium Botualinum – anaerobic bacteria that
cause food poisoning (also used for Botox
injections)
E. Coli (Escherichia Coli)– Human intestinal
bacteria
Anthrax- related to Botualism (Bacillus anthracis)
Diseases
Importance of Monerans
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Food Production
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Buttermilk, cottage cheese, yogurt, sour cream, sauerkraut,
pickles
Also cause food spoilage (milk, fruits, meats)
Recycle the remains of dead/decaying plants and
animals
Fix/produce important gases in our atmosphere
Industrial chemical production
Clean up the environment
Genetic engeenring: because they are simple, unicellular,
very few mutaions; we can study an predict genetic
variablitiy
Factors affecting growth
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Temperature (39 degrees Celcius/79
degrees Fahrenheit)
Radiation (UV)
Chemicals (disinfectants/alcohol)
Available food
Available O2
Prevention of Bacterial Growth
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Refrigeration
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Boiling
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All living things need water
Salting
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High heat for a defined period of time, followed by
rapid cooling
Drying
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Sterilizes
Pasteurizing food
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Slows reproduction
Similar to drying, will draw water out of bacterial cells
Canning
Control of Bacterial Growth:
Physical Agents
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Dry Heat (passed through a flame)
Moist heat/steam
Boiling (100 degrees Celsius (212F) for 15
min
Freezing: -20 C
Radiation energy: UV light or x-rays
Chemical Agents (Disinfectants)
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Acid (low pH) or base (high pH)
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Alcohol: 70% isopropyl (rubbing alcohol)
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All organisms have an optimal range for
homeostasis
Other types of alcohol work as well
Phenol lysol: Popular household cleaner
Detergents, or surfactants which are
popular in antibacterial hand soaps
Antibiotic Drugs
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Grouped based upon their mode of action
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Cell wall synthesis inhibitors (CWSI)
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Penicillin
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Cephalosporins
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Ampicillin, Amoxicillian, and G and V
Keflex, Ceftin, Ceflex
Bacitracin
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Used in ointments
Protein Synthesis Inhibitors
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PSI
Tetracycline
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Used in treatment of acne/skin infections
Erythromycin
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Derivative is Azithromycin
Come in a Z-pak
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Known as zithromax
Clarithromycin
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Known as biaxin
Nucleic Acid Synthesis Inhib.
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NASI
Cipro
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Block synthesis of bacterial DNA
Only drug that can be used to treat inhalation
anthrax
Cell Metabolism Inhib.
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CMI
Sulfa drugs
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Synthetic antibiotics
Most other antibiotics produced form
chemicals released by living organisms
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Fungi and bacteria in most cases