Download Bacterial & Viral Infection

Bacterial & Viral Infection
Georgia Performance Standards
SB3b. Compare how structures and functions vary between
the six kingdoms (archaebacteria,eubacteria, protists, fungi,
plants, and animals).
SB3d. Compare and contrast viruses with living organisms.
Essential Questions:
• Are viruses alive?
•What is the role of evolution in antibiotic and pesticide
resistance?
Warm-up:
• Use your kingdoms chart to construct a
Venn diagram of the 2 different bacterial
kingdoms.
Bacteria (Prokaryotes):
• Prokaryotes are identified by their
– Shapes
– chemical natures of their cell walls
– the ways they move
– the ways they obtain energy
Basic Shapes of Prokaryotes
Prokaryotes can be identified by their shapes.
Rod-shaped
prokaryotes
are called
bacilli
Spherical
prokaryotes
are called
cocci
Spiral and
corkscrew-shaped
prokaryotes are
called spirilla
Prokaryotic (Bacterial) Cell Walls
• Gram-positive
– Bacterial cells with
a cell wall
containing
peptidoglycan
– Absorb only the
violet dye
– Appear purple
under the
microscope
• Gram-negative
– Bacterial cells with a cell
wall containing
peptidoglycan and an
outer layer of lipids and
carbohydrate molecules
– Absorbs only the red
stain.
– These bacteria are red
under the microscope
The Structure of a Eubacterium
Section 19-1
Ribosome
Peptidoglycan
Cell
Cell
wall membrane
Flagellum
Go to
Section:
DNA
Pili
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Movement
 Prokaryotic flagella are made of filaments.
 Flagella help prokaryotes to move toward
materials that they need to survive.
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Photoautotrophs
 Carry out photosynthesis in a similar manner
as plants
Chemoautotrophs
 Break down and release inorganic compounds
that contain nitrogen or sulfur
Aerobes and Anaerobes
 Obligate aerobes are bacteria that require oxygen
to grow.
 Anaerobic bacteria do not use oxygen for growth
or metabolism.
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Reproduction of Prokaryotes
 Binary Fission
 Division of a cell into two
genetically identical cells
 Conjugation
 Two prokaryotes attach to each other
and exchange genetic information.
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Survival of Bacteria
 Endospores
 Resistant to harsh
environments and might be
able to survive extreme
heat, extreme cold,
dehydration, and large
amounts of ultraviolet
radiation
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Mutations
 Bacteria reproduce quickly and their
population grows rapidly.
 Mutations lead to new forms of genes, new
gene combinations, new characteristics, and
genetic diversity.
Bacterial Disease
• Pathogens = any disease causing agent
– Pathogenic bacteria are harmful because they
damage the host’s tissue in two ways.
• Breaking down the tissue of an organism for
food. (Heterotrophic bacteria)
– EX: TB
• Producing toxins that are released (Botulism
poisoning)
How are bacteria diseases transmitted?
– Water = Cholera- produced a toxin that causes
diarrhea, vomiting, dehydration, and death
– Air = TB, scarlet fever, whopping cough
– Food = botulism – toxin released by Clostridium
botulinum that can cause paralyses and death.
Salmonella
– Insects = Bubonic plague – carried by fleas & Lyme
disease –carried by ticks.
– Direct human contact = Leprosy
Common Diseases Caused by Bacteria
Section 19-2
Go to
Section:
Disease
Pathogen
Prevention
Tooth decay
Streptococcus mutans
Regular dental hygiene
Lyme disease
Borrelia burgdorferi
Protection from tick bites
Tetanus
Clostridium tetani
Current tetanus vaccination
Tuberculosis
Mycobacterium tuberculosis
Vaccination
Salmonella food poisoning
Salmonella enteritidis
Proper food-handling practices
Pneumonia
Streptococcus pneumoniae
Maintaining good health
Cholera
Vibrio cholerae
Clean water supplies
Controlling Bacteria
• Sanitation & hygiene
– Water purification plants
– Sterilization = a process in which bacteria is destroyed by
subjecting them to either great heat or to chemical action. –
• Disinfectants, salting, vinegar
• Hot & Cold Treatments Protect Food from bacterial
Contamination
– high heat limits growth of most bacteria (pasteurization)
• Kills bacteria and destroys toxins
– bacteria grow slower at colder temperatures
Antibiotics & Vaccines
• Antibiotics:
– 1928 Alexander
Fleming = accidentally
develop the 1st
antibiotic called
penicillin, which was
a chemical actually
produced by a mold
(fungus). The chemical
is poisionous to
bacteria, but not to
humans.
– Other antibiotics are
tetracycline,
streptomycin
• Vaccines:
– a solution containing
pathogens/toxins that are
made harmless by high heat
or genetic engineering.
– Immune system makes
antibody proteins against
them.
– Once vaccinated, your
immune system has
defenses ready to destroy
any live pathogens before
they have a chance to make
you sick.
– 1881Louis Pasteur = made
the first effective vaccine for
anthrax
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Foods and Medicines
 Some foods are made with the aid of
bacteria.
 cheese
 yogurt
 buttermilk
 pickles
 vitamins
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Ecology of Bacteria
 Nutrient cycling and nitrogen fixation
 Bacteria are decomposers, returning vital
nutrients to the environment.
 Nitrogen-fixing bacteria live in a symbiotic
relationship in the root nodules of plants
such as soybeans, clover, and alfalfa.
Chapter
18
Bacteria and Viruses
18.1 Bacteria
Normal Flora
 Most of the bacteria that live in or on you
are harmless and are called normal flora.
21,674x
E. coli
What is a Virus?
• Virus = microscopic particles that invade
cells of plants, animals, fungi, and
bacteria.
• Capsid = a protein coat that surrounds a
core of genetic material
– Some viruses have DNA as the genetic
material, and others have RNA as the
genetic material EX: HIV and flu
Figure 19-13 Virus Structures
Section 19-3
Tobacco Mosaic
Virus
T4 Bacteriophage
Head
DNA
Influenza
Virus
RNA
Capsid
proteins
Capsid
RNA
Tail
sheath
Tail
fiber
Surface
proteins
Go to
Section:
Membrane
envelope
Characteristics of Viruses:
•
•
•
•
Viruses are not cells
Viruses are not alive
Viruses do not use energy
Viruses can reproduce only when inside
living cells
• Viruses do contain genetic info. & can
evolve over time.
Common Diseases Caused by Viruses
Section 19-3
Go to
Section:
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
DNA
cancer
Retroviruses
RNA
cancer, AIDS
Adenoviruses
DNA
respiratory infections
Herpesviruses
DNA
chickenpox
Poxviruses
DNA
smallpox
How do Viruses reproduce?
• Viruses take over the reproductive machinery of a cell Ex:
HIV
• Proteins on the cell surface of viruses bind to receptor
proteins on the host’s cell surface.
• Viral RNA is releases into the cell and a viral enzyme called
reverse transcriptase makes a DNA copy of the viral protein.
• The cell them begins to produce HIV viral proteins and genes
that can assemble to form new genes.
• Newly produced viruses may break out of the cell by budding
through the cell membrane, or they may burst the cell
membrane, causing it to die.
Viral Infection: Ex: HIV  AIDS
• Lytic infection = a virus enters the cell,
makes a copy or itself, and lyses the cell.
• Lysogenic infection =
– a virus embeds its DNA into the DNA of the
host cell (Prophage) and is replicated along
with the host cells’ DNA.
– The host cell is not lysed right away.
The Lytic Cycle
Section 19-3
Bacterioph
age protein
coat
Bacteriophage DNA
Bacterial chromosome
Bacteriophage enzyme lyses the
bacterium’s cell wall, releasing
new bacteriophage particles that
can attack other cells.
Bacteriophage
attaches to
bacterium’s cell wall
Lytic Cycle
Bacteriophage
injects DNA into
bacterium
Bacteriophage
proteins and
nucleic acids
assemble into
complete
bacteriophage
particles
Go to
Section:
Bacteriophage
Bacteriophage
takes over
bacterium’s
metabolism,
causing synthesis of
new bacteriophage
proteins and nucleic
Bacteriophage DNA
Bacteriophage protein
A Lysogenic Infection
Section 19-3
Bacterial
chromosome
Bacterioph
age DNA
Bacteriophage
injects DNA
into bacterium
Bacteriophage DNA (prophage)
can exit the bacterial chromosome
Lytic
Cycle
Bacteriophage enzyme lyses
the bacterium’s cell wall,
releasing new bacteriophage
particles that can attack other
cells
Go to
Section:
Lysogenic
Cycle
Bacteriophage
DNA forms a
circle
Bacteriophage
proteins and nucleic
acids assemble into
complete
bacteriophage
particles
Prophage
Bacteriophage DNA
(prophage) may replicate
with bacterium for many
generations
Bacteriophag
e DNA inserts
itself into
bacterial
chromosome
Types of Viruses:
• Bacteriophage = viruses that infect bacteria
– EX: T4 and lambda bacteriophages
• Tobacco mosaic virus = 1st virus isolated in
1933
• Retrovirus = any virus that used reverse
transcriptase to make DNA copies from RNA.
Defenses Against Viruses:
• Why can’t we treat viral diseases with
antibiotics?
• Vaccinations also protect against some viral
diseases.
– Harmless viruses stimulate the immune system to
create defenses against the harmful form of the virus.
– Vaccines only work on viruses whose surface
proteins do not change (mutate). (Small pox,
measles, polio)
• HIV, cold viruses, and flu viruses (genes mutate too often for
vaccines to become effective)
Defenses Against Viruses:
• 1798 Edward Jenner = developed the 1st
vaccine for small pox.
– Immunization = Infected 2 yr old son with live
cowpox virus and son didn’t get sick.
• Cowpox virus and smallpox virus have similar
protein coats.
• After vaccination, the immune system creates
defenses that recognize the shape of the cowpox
protein coat.
• These defenses cannot differentiate a cowpox
virus from a smallpox virus, so they destroy either
virus whenever it is encountered.
Homework:
• Complete bacterial and viral WS
• Complete Chapter 19 Guided Reading
(Due Friday)