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Microbiology
Bacteria, Viruses, Protists, and Fungi
Bacteria

Bacteria are classified into two kingdoms:
 Eubacteria (true bacteria) and Archaebacteria
(Ancient Bacteria).
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Until recently, bacteria were placed into one
Kingdom - The Kingdom Monera, hence
sometimes bacteria are referred to as Monerans
Bacteria

Bacteria are the MOST NUMEROUS
ORGANISMS ON EARTH
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Bacteria have evolved into many different forms,
and they are now part of nearly every
environment on Earth
 They have been found at the bottom of the
oceanic trenches 9.6 km (6 mi) below the
water's surface and in Arctic and Antarctic
Regions.
Reactivity with Oxygen

Obligate Aerobes - require oxygen for
respiration, need oxygen to grow and survive

Obligate Anaerobes - must avoid oxygen,
they will die in its presence

Facultative Anaerobes - can use oxygen
when it is available, but can also do without it
Archaebacteria

Archaebacteria tend to live in extreme
environments - sometimes they are called
"Extremophiles"
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Halophiles - salt lovers
Methanogens - produce methane as a by-product
Thermoacidophiles - love hot, acidic environments
Eubacteria

Classified according to their mode of
getting nutrients, mechanism of
movement, and their shape
Shape of Bacteria / Naming

Cocci - sphere
Bacilli - rods
Spirilla - spirals

Diplo - in pairs
Staph - in clusters
Strep - in chains
Bacteria Morphology

Structures that help bacteria survive in hostile
environments
 capsules (slime layers) - help evade immune system and
adhere to surfaces
 pili - hairlike projections
 endospores - bacteria become dormant until conditions
become favorable
Bacteria Morphology

Movement
 Flagella – one or more tail-like structures

Reactions
 chemotaxis - response to chemicals
 phototaxis - response to light
 magnetotaxis - response to magnetic field
Gram Stain

Gram's Stain is a widely used method of staining
bacteria as an aid to their identification. It was
originally devised by Hans Christian Joachim Gram,
a Danish doctor.

Gram's stain differentiates between two major cell
wall types.

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Gram-Negative: Bacterial species with walls containing
small amounts of peptidoglycan
Gram-Positive: Bacteria with walls containing relatively
large amounts of peptidoglycan
Gram Negative –
light red or pink color
Gram Positive +
dark purple
Escherichia coli, Salmonella typhi,
Vibrio cholerae and Bordetella
pertussis
Staphylococcus epidermidis,
Streptococcus pyogenes, and
Clostridium tetani
Bacterial Reproduction

Occurs by binary fission - one cell
splits into two cells, offspring are
genetically identical to parent

Bacterial conjugation - a form of
sexual reproduction where bacteria
exchange genetic information before
dividing, offspring have new genes
(and new traits)
Bacterial Reproduction

Transformation - bacteria incorporate genes from
dead bacteria

Transduction - viruses insert new genes into bacterial
cells. This method is used in biotechnology to create
bacteria that produce valuable products such as insulin
Bacterial Transformation
Bacteria and Health

Some diseases caused by bacteria:
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Tetanus
Botulism
Syphilis
Lyme disease
Strep throat
Pneumonia
Anthrax
Necrotizing fasciitis (flesh eating bacteria)
Toxic shock syndrome
Treatments

Antibiotics & Antiseptic solutions
Antibiotics and Antiseptics

Joseph Lister created the first antiseptic,
an acid to spray on tables and instruments
before surgery (1860)

The Discovery of Penicillin
 Alexander Fleming
 Noticed mold growing on petri dishes
 Bacteria did not grow where the mold was
 He isolated the chemical that killed bacteria, but
it was not stable
 Howard Flory continued the work, later
stabilized the chemical
 Fleming and Flory received the Nobel Prize in
1945
Viruses

Properties of viruses

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Possess no membranes, cytoplasm, ribosomes,
or other cellular components
Cannot move or grow
Can only reproduce inside a host cell
Consist of 2 major parts - a protein coat, and
hereditary material (DNA or RNA)
Extremely tiny, much smaller than a cell and only
visible with advanced electron microscopes
Viruses and their Hosts

Viruses are specific to their hosts.
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They can only attack specific cells, and not all
viruses can pass between different species (though
some can).
Rabies, for instance, can be passed from animal to
human.
HIV is a virus that seems specific to humans.
Viruses and their Hosts

The common cold is a virus that specifically
attacks cells of the respiratory track (hence the
coughing and sneezing and sniffling).

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Other viruses attack other types of cells.
HIV virus specifically attacks white blood cells.
Influenza

Influenza, often called the FLU, is an acute, highly
contagious infection of the respiratory tract which
commonly occurs in the winter.

Influenza results from different strains of the
influenza virus. This virus has the ability to mutate
into different forms. That is why although you were
exposed to similar strains in the past, you might not
be able to defend yourself against a new one.

Symptoms

Vaccine
Flu Virus
Smallpox Virus

Incubation period before symptoms:10-14 days

Symptoms: high fever, headache, backache, and vomiting, rash (pox) on
the face and arms that spreads to the trunk

How it would be spread
Aerosol or person-to-person, potentially by a terrorist-"martyr." It is highly
contagious. However, smallpox victims show clear signs of the disease, and
anyone who came in contact with them could be vaccinated post-exposure.

Treatment: There is no current treatment against the smallpox virus.
Vaccination given 3-5 days post-exposure can prevent the disease.

Vaccine:Vaccine exists but is currently not recommended for the general
public. Stockpiles of vaccine are being increased. No one in the U.S. has
been vaccinated since 1972, and people vaccinated before then have likely
lost immunity.
Variola (Smallpox) Virus
Smallpox
Streptococcus

Strep throat is an infection caused by group A
streptococcus bacteria, and it's very common
among kids and teens. The symptoms of strep
throat include fever, stomach pain, and red,
swollen tonsils.

Strep throat usually requires treatment with
antibiotics. With the proper medical care - along
with plenty of rest and fluids - your child should
be back to school and play within a few days.
Strep Throat
HIV

HIV Animation

Human immunodeficiency virus (HIV) is a that can lead to AIDS, a condition
in humans in which the immune system begins to fail, leading to life-threatening
opportunistic infection. Previous names for the virus include human Tlymphotropic virus-III (HTLV-III), lymphadenopathy-associated virus (LAV),
and AIDS-associated retrovirus (ARV).

Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, preejaculate, or breast milk. Within these bodily fluids, HIV is present as both free
virus particles and virus within infected immune cells. The four major routes of
transmission are unprotected sex, contaminated needles, breast milk, and
transmission from an infected mother to her baby at birth. Screening of blood
products for HIV has largely eliminated transmission through blood transfusions
or infected blood products in the developed world.

HIV infection in humans is now pandemic. As of January 2006, the UNAIDS and
the WHO estimate that AIDS has killed more than 25 million people since it was
first recognized on Dec. 1, 1981, making it one of the most destructive
pandemics in recorded history.
Related to Viruses

Viroids - even smaller than viruses, consist of
RNA strands that lack a protein coat

Prions - infectious agents that are believed to
be the cause of Mad Cow Disease, relatively
new find and much is not known about them
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Bacteriophage - viruses that infect bacteria
Viral Reproduction

Lysogenic (Prophage) Pathway - the virus
stays within the cell until certain
environmental triggers cause it to enter the
lytic cycle
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Lytic Pathway - rapid replication of the virus,
ending in cell lysis (or death). More phages
are released to infect other cells
Lysogenic
Cycle
Lytic Cycle
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A: Virus attaches to host and injects its
nucleic acid
B: Viral nucleic acids and proteins are made
C: New virus particles are assembled
D: Host cell breaks open and virus particles
are released to infect other cells
Protists
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Protists are divided into 3 major categories

Plantlike Protists
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Animal-like Protists
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Photosynthetic
algae
Heterotrophic
called protozoa ("first animal")
Fungus-like Protists
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resemble fungi
absorptive protists
slime molds and water molds
Plant-Like Protists
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Dinoflagellata - 2 flagella
Golden Algae – chrysophyta
Green Algae – chlorophyta
Brown Algae – phaeophyta
Red Algae – rhodophyta
Diatoms - major component of plankton
Green Algae
(Spyrogyra)
Diatoms
Animal-Like Protists
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Rhizopoda
 move using pseudopods (false feet), ex. ameba, eat by
phagocytosis
Foraminifera
 have a shell, some have photosynthetic algae in the shell
Actinopoda
 helizoans and radiozoans
Apicomplexa
 parasitic protists, formerly known as sporozoa, Malaria is caused
by a protist in this group
Zooflagellates
 have a flagella, member of this group causes African Sleeping
Sickness
Ciliophora
 use cilia to move, live in water, ex. paramecium
Ameba
Paramecium
Radiolarian
Fungus-like Protists
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Myxomycota - slime molds, produce spores
to reproduce, they grow and eat as a mass
Acrasiomycota - cellular slime molds, solitary
but can work together
Oomycota - water molds
Slime Molds
Fungi Characteristics
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Habitat
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Air, food, gardens, and
water
Warm temperatures (2030°)
Once classified as
plants because:
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Grow anchored in soil
Cell walls
Fungi Characteristics
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Structure
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Cell walls – made of
chitin
Hyphae
 Anchor the fungus
 Invade food source
 Form reproductive
structures
Septa
 Divide the hyphae
into individual cells
Fungi Types
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Saprophytes
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Mutualists
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Decomposers that feed on dead organic material
Symbiotic relationship (ex. Algae)
Parasitic fungi
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Absorb nutrients from hosts
Fungi Adaptations
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Role
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Benefits of increased surface area (hyphae)
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Decompose Earth’s organic wastes
Nutrient absorption
What would happen if there were no fungi?
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Huge amounts of waste, dead organisms, and
debris would litter the Earth
Fungi Reproduction
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Fragmentation
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Pieces of hyphae are broken by mycellium and grow
into new mycelia
Budding
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Asexual reproduction – mitosis occurs and new
individuals pinch off from parent
Fungi Reproduction continued…
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Spores (reproductive cells)
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Spores transported to a favorable location
Hypha emerge and begin to grow
Advantages of Spore Reproduction
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Sporangia protect spores (from drying out)
Large number of spores increase germination rate
and increase survival rate
Lichens
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Symbiotic
relationship
between a
fungus and
an alga or
cyanobacteria