Transcript Viruses & Bacteria

Viruses & Bacteria
Chapter 19
Pages 471 - 490
Compare/Contrast
Prokaryotes (Bacteria)
Eukaryotes
Smaller
Simpler
Has genetic material
No nucleus
Grow, reproduce, &
respond to environment
Some move by gliding
or swimming
Some have internal
membranes
Unicellular
Larger
Complex
Has genetic material
Nucleus
Grow, reproduce, &
respond to environment
All move
Have internal membranes
Unicellular & multicellular
Has organelles & cytoplasm
Pathogen – disease causing
organisms
• Virus
• Bacteria
• Fungi
• Protozoans
Bacteria
• Prokaryotes
–Smallest, most common
microorganism
–Single-celled
–Lack nucleus
–Has DNA
Bacteria
• 2 Kingdoms
• Archaebacteria
– Look similar.
– Live in harsh environments.
– Lack peptidoglycan in the cell wall.
– Have different membrane lipids.
– DNA sequences of key genes are more like
those of eukaryotes than eubacteria.
– Are thought to be ancestors of eukaryotes.
– Ex. Methangones- produce methane gas.
Bacteria
• 2 Kingdoms
• Eubacteria (pg. 472)
– live almost everywhere, larger of the two.
– Usually surrounded by a cell wall made up
of carbohydrate & peptidoglycan.
– Cell membrane inside cell wall.
– Cytoplasm.
– Ex. E coli
Bacteria
• How we Identify Prokaryotes (cont.):
– How they release energy by cellular respiration and
fermentation
• Obligate aerobes – require constant supply of oxygen. Ex.
Tuberculosis.
• Obligate anaerobes – do not require oxygen. Oxygen could
kill it. Ex. Botulism is found in canned food that’s not properly
sterilized.
• Facultative anaerobes – can survive with or without oxygen.
Can live anywhere. Ex. E coli which is found in the large
intestines or in sewage or contaminated water.
Bacteria contain:
•one circular piece of DNA
•tiny circular pieces of DNA
called plasmids
•ribosomes
Bacteria have cell walls made of:
•peptidoglycan (a sugar linked to
chains of amino acids).
•this may be covered with an outer
membrane of lipopolysaccharide
(chain of sugar with a fat attached).
Some bacteria:
• have a gelatinous layer called a
capsule surrounding the cell wall.
• form thick-walled endospores
around chromosomes when they
are exposed to harsh conditions
(drought, high temperatures) these types cause botulism
Some bacteria have:
• flagella for
locomotion.
• pili (short, thicker
outgrowths that
help cell to
attach to
surfaces)
Cell Morphology
• Bacteria vary widely
in size.
• There are three
basic shapes:
– Round or spherical:
cocci (coccus)
– Rod-shaped: bacilli
(bacillus)
– Curved or spiral
shaped: spirilla
Cell Morphology
• There are different
arrangements:
– Pairs of spheres:
diplococci
– Chains of spheres:
streptococci
– Clusters of spheres:
staphylococci
Gram Reactions
• Bacteria can be
classified into two
categories based on
their reaction to a Gram
stain
– Gram + stain purple.
– Gram – stain pink to
red.
• This color difference is
due to the thickness of
cell wall.
– Gram + are thick
– Gram – are thin
Bacteria
• How we Identify Prokaryotes:
• Shape – bacilli, cocci, spirilla.
• By the way they move.
• By the way they obtain energy.
– Most are Heterotrophes which obtain energy by
consuming food.
» Chemoheterotroph- Ex. Botulism (food poisoning).
» Photoheterotroph- uses photosynthesis.
– Autotrophs make their own food.
» Chemoautotroph- found in deep ocean floors.
» Photoautotroph- found near surface in lakes oceans &
streams.
• The chemical nature of their cell walls.
– A method of Gram Staining is used to determine nature.
Gram (+) = violet, Gram (-) = pink.
Bacteria
• How we Identify Prokaryotes:
• Shape – bacilli, cocci, spirilla.
• By the way they move.
• By the way they obtain energy.
– Most are Heterotrophes which obtain energy by
consuming food.
» Chemoheterotroph- Ex. Botulism (food poisoning).
» Photoheterotroph- uses photosynthesis.
– Autotrophs make their own food.
» Chemoautotroph- found in deep ocean floors.
» Photoautotroph- found near surface in lakes oceans &
streams.
• The chemical nature of their cell walls.
– A method of Gram Staining is used to determine nature.
Gram (+) = violet, Gram (-) = pink.
Bacteria
• Reproduction
– Binary fission – DNA replicates & divides
producing 2 daughter cells. Asexual
reproduction.
– Conjugation – process where genetic
information is exchanged.
– Spore formation – an endospore may form
when growth conditions become unfavorable.
Bacteria reproduce:
asexually using binary fission.
Bacteria reproduce:
sexually using conjugation.
Bacteria
exchange
plasmid DNA.
This is how
bacteria become
antibiotic
resistant.
There are three types of bacteria
based on how they obtain energy:
heterotrophs, photosynthetic, and
chemoautotrophs.
This is the
anthrax
bacterium.
1.Most are heterotrophs:
a. Decomposers – feed on and recycle
organic material
b. Pathogens – parasitic, disease-causing
bacteria
• Either attack cells or secrete toxins
c. Nitrogen-fixing bacteria (Rhizobium)
• Found in nodules of soybeans,
peanuts, alfalfa, and clover
• Convert atmospheric nitrogen (N2) into
ammonia, called nitrogen fixation.
• Used in crop rotation
Nitrogen fixing bacteria
in the nodules of roots
2. Some are photosynthetic.
•These are autotrophs that use
the sun’s energy to make food.
3. Chemoautotrophs
•Obtain energy from molecules like
ammonia and methane to make food.
•Examples: Nitrobacter and Nitrosomonas
- live in soil
- have a crucial role in nitrification
(turn ammonia into nitrates, the form of
nitrogen commonly used by plants).
Bacteria produce disease in 2
ways:
• Bacteria damage the cells & tissues of
the infected organism directly by
breaking down the cells for food.
• Bacteria release toxins (poisons) that
travel throughout the body interfering
with the normal activity of the host.
A Summary of Bacterial Diseases
Disease
Pathogen
Area affected
Mode of
transmission
Botulism
Closridium
botulinum
Nerves
Improperly
preserved foods
Cholera
Vibrio cholerae
Intestine
Contaminated
water
Dental caries
(tooth decay)
Streptococcus
mutans,
sanguis and
salivarius
Teeth
bacteria enter
the mouth from
the environment
Gonorrhea
Neisseria
gonorrhoeae
Urethra,
fallopian tubes,
epididymis
Person to
personby
sexual contact
Lyme disease
Borrelia
burgdorferi
Skin, joints,
heart
Tick bite
A Summary of Bacterial Diseases
Disease
Pathogen
Area affected
Mode of
transmission
Rocky mountain
spotted fever
Rickettsia
ricketsii
Blood, skin
Tick bite
Salmonella food
poisoning
Salmonella
Intestine
Contaminated
water and food
Strep throat
Streptococcus
pyogenes
Upper
respiratory
tract, blood,
skin
Person to
person by
sneezes,
coughs or
direct contact
Tetanus
Clostridium
tetani
Nerves at
synapses
Contaminated
wounds
Tuberculosis
Mycobacterium
tuberculosis
Lung, bones,
other organs
Person to
person by
coughs
• work by preventing cell wall
formation, breaking up cell
membranes, or disrupting
chemical processes.
•cannot treat viral infections.
A Summary of common Antibiotics
Antibiotic or synthetic
drug
Mechanism of action
Target bacteria
Penicillin
Inhibits cell-wall
synthesis
Gram-positive bacteria
Ampicillin
Inhibits cell-wall
synthesis
Broad spectrum
Bacitracin
Inhibits cell-wall
synthesis
Gram-positive bacteria;
used as skin-ointment
Tetracycline
Inhibits protein
synthesis
Broad spectrum
Streptomycin
Inhibits protein
synthesis
Gram-negative bacteia,
tuberculosis
Sulfa drug
inhibits cell
metabolism
Bactrial meningitis,
urinary tract infections
Rifampin
Inhibits RNA synthesis
Gram-positive bacteria
and some Gram
negative bacteria
Quinolines
Inhibits DNA synthesis
Urinary-tract infections
Strep throa
Streptococcus
Staphylococcus
Gonorrhea-Passed from Mother to
Baby
Syphilis
Helpful Bacteria
• Decomposers break down dead organic material
• Biotechnology - inserting helpful genes into a
plasmid
• Bioremediation - bacteria eat up oil spills
• Food production – cheese and yogurt
• Put nitrogen back into the soil
• Aid in digestion
Interdependence
VIDEO CLIP
Viruses and
organisms rely
on their
environment
and other
species for survival.
Little Assassins: What are Virus
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at+are+viruses
Viruses
• Must infect living cells in order to
reproduce.
• Are Parasites.
• Are not considered to be living things
because they are not made up of cells &
cannot live independently.
• See Chart on pg. 483
Viruses
Viruses are NOT cells. A virus
is an infectious agent made up
of:
•a core of nucleic acid (RNA or DNA)
•a protein coat
Alive or not?
Even scientists disagree as to
whether or not viruses are
alive. What do you think? Look
at the chart on the next page
to help you decide.
Study of Viruses
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s+work
Grouping Viruses
• Viruses occur in different shapes.
Helical and icosahedral are two
examples of virus shapes
Characteristic
of life
CELL
VIRUS
Made of cells
YES
NO
Obtain & use
energy
YES
NO
Grow & develop
YES
Reproduce
YES
Respond &
adapt
Contain RNA or
DNA
Only inside a
living cell
Only inside a
living cell
YES
YES
YES
YES
Structure
of a virus
ENVELOPE
• Envelope (part of
the protein coat)
• Capsid (part of
the protein coat)
• Nucleic acid
(either DNA or
NUCLEIC
RNA)
ACID
CAPSID
How viruses work
•
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5 Steps of Replication
1. Attachment
2. Injection of genetic material
3. Making new parts
4. Assembly of parts
5. Release of new parts
AIMAR
Bacteriophage
• A virus that only
infects bacteria
• Ex. Bacteriophage
T4
CAPSID
HEAD
DNA
CAPSID
TAIL
FIBER
VIRUSES
VIRUSES, CONT.
Ticking time
bombs . . .
Viruses do not reproduce,
EXCEPT inside a living cell.
They invade a living cell and
let the cell do the work for
them.
Viruses
• Once inside a host cell:
pg. 481
– Lytic infection
• Virus inters cell and makes copies of itself.
• Causes cell to burst, releasing new virus particales that
can attack other cells.
• It then uses materials of host cell to make copies of its own
DNA molecule.
• Host cell is destroyed.
– Lysogenic infection
• Virus integrates its DNA into the DNA of host cell.
• The viral genetic info. replicates along with the host cell’s
DNA.
• Viral DNA that’s embedded in host’s DNA is called
prophage.
• Unlike lytic, it does not lyse the host cell right away so it
may remain a part of DNA of host for many generations.
Lytic Cycle
An infection that kills the host cell
rapidly.
Virus inters cell and makes copies of
itself.
Causes cell to burst, releasing new virus
particales that can attack other cells.
It then uses materials of host cell to
make copies of its own DNA molecule.
Cycle Illustration
1
2
4
3
5
Lysogenic Cycle
A viral infection that integrates its DNA into the
DNA of host cell, remains harmless for a period of
time (sometimes years), and then becomes harmful
later.
The viral genetic info. replicates along with the
host cell’s DNA.
Viral DNA that’s embedded in host’s DNA is called
prophage.
Unlike lytic, it does not lyse the host cell right
away so it may remain a part of DNA of host for
many generations.
Viral Diseases
• Viruses disrupt the body’s normal
equilibrium.
• Viruses attack & destroy certain body cells
causing the symptoms of the disease.
• Diseases:
–
–
–
–
–
Common cold
Influenza
AIDS
Chickenpox
Measles
• Can produce other serious diseases in both animals & plants.
• Plant viruses have a difficult time entering cells they
infect partly because plant cells have though cell walls.
Viral Diseases
• 2 Virus like particles can cause disease:
• Viroids – single-stranded RNA molecules that have
no surrounding capsoid. (cause disease in plants).
– Ex. Tobacco mosaic virus.
• Prions – particles that contain only protein which
have no DNA or RNA. (cause disease in animals &
humans).
– Ex. Foot & mouth disease in livestock.
Viruses Throughout history
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Some Common Viruses of Humans
Viral group
Nucleic
acid
Shape and
Structure
Example of
diseases they
cause
Mode of
Transmission/
Effect on Body
Papovaviruses
DNA
Icosahedral, nonenveloped
Human
papillomavirus
(HPV)
Mother to child
at birth, sexual
activity/ Warts,
cancer
Adenoviruses
DNA
Icosahedral, nonenveloped
Respiratory and
intestinal
infections
Direct contact ,
inhalation/
colds,
bronchitis, fever,
sore throat, pink
eye…
Herpesviruses
DNA
Icosahedral,
enveloped
Herpes simplex,
chickenpox,
shingles,
infectious
mononucleosis
Direct Contact,
eat or drink
after/ blisters,
sore throat,
fever, enlarged
spleen
Poxviruses
DNA
Complex brickshaped,
enveloped
Smallpox,
cowpox
Inhalation/
Lesions,
blindness, fever,
often fatal
Some Common Viruses of Humans
Nucleic
acid
Shape and Structure
Example of
diseases they
cause
Mode of
Transmission/
Effect on Body
Rhinovirus
RNA
Icosahedral, nonenveloped
Common cold
Direct contact with
secretions,
inhalation/ sinus
congestion, sore
throat, sneezing,
cough, fever,
aches, fatigue
Ebolavirus
RNA
Threadlike
Ebola
structure, enveloped
Body fluids/ High
fever,
uncontrollable
bleeding
Rubulavirus
(rubella virus)
RNA
Helical, enveloped
Mumps,
measles
Direct contact with
infected person or
objects, inhalation/
Parotid and
salivary gland
swelling, possible
deafness
Flavivirus
RNA
Hairpin structure
Yellow fever
Bite of infected
mosquito/ rash,
fever, nausea, pain,
aches, jaundice
Viral group
Some Common Viruses of Humans
Nucleic
acid
Shape and Structure
Example of
diseases they
cause
Mode of
Transmission/
Effect on Body
Picornaviruses
RNA
Icosahedral, nonenveloped
Poliomylitis,
hepatitis A, B,
C, & cancer
Contaminated
blood, food,
needles or water.
Sexual contact/
Flulike symptoms,
swollen liver,
jaundice
Myxovirus
RNA
Helical, enveloped
Influenza A, B,
and C
Inhalation/ fever,
cough fatigue, sore
throat, headache,
muscle ache
Rhabdoviruses
RNA
Helical, enveloped
rabies
Bite of infected
animal/
depression, fever,
paralysis, fatal
Retroviruses
RNA
Icosahedral,
enveloped
AIDS, Cancer
Sexual contact,
contaminated
blood or needles/
Immune system
failure
Viral group
Retrovirus
• A virus that contains
•
•
•
•
RNA instead of DNA
Genetic information is
ENVELOPE
copied backwards
It may remain dormant
for any length of time
before becomes active RNA
and it can cause death
of the host cell.
Human
Immunodeficiency Virus
(HIV) is a retrovirus
HIV causes AIDS
CAPSID
HIV
• Transmitted when the body fluids of an
infected individual are passed on to an
uninfected individual by direct contact or
contaminated objects.
• Breaks down immune system, so can no
longer fight off disease
– Hides in Helper T cells
• People w/HIV, then AIDS suffer from two
rare problems.
– Pneumosystis carinii – protozoan
infections of lungs
– Kaposi’s sarcoma - cancer
MEASLES
SMALLPOX
HERPES
Jenner and Pasteur
• Edward Jenner, English Doctor….
– Invented vaccine
– Infected own son with cow pox (a mild
form of small pox)
– Son didn’t contract small pox
– Cow pox triggered immune system to
create an immunity against small pox
Jenner and Pasteur
• Louis Pasteur
–Pasteurization
–Disproved spontaneous generation
–Said “life came from life”
–Boiled broth to kill microorganisms
What is an epidemiologist?
• A scientist who studies the causes and
controls of disease outbreaks.
• Involved in preventing disease outbreaks
and in stopping outbreaks that do occur
spreading.
• Work for CDC, FBI, etc.
1918
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Inoculation & Incubation of culture
medium
• Culture medium – either a broth or an
agar with nutrients added to it to aid in the
growth of microorganisms.
• Inoculation – referred to as a streak or
stab (putting microorganisms in a nutrient
agar or broth so they can grow)
• Incubation – usually 24 – 48 hours at a
temperature of 20º C or 37º C.
Inoculation Technique
Heat loop
Inoculation
Inoculation Broth
Inoculation Slant
Agar Deep
Agar Plate
Streak Plates
Finished Product
Koch’s Postulates
1. The pathogen must be found in an animal with
the disease and not in a healthy animal.
2. The pathogen must be isolated from the sick
animal and grown in a laboratory culture.
3. When the isolated pathogen is injected into a
healthy animal, the animal must develop the
disease.
4. The pathogen should be taken from the
second animal and grown in a laboratory
culture. The cultured pathogen should be the
same as the original pathogen.
Infectious vs. Noninfectious
diseases
• Infectious disease - Any disease
caused by the presence of pathogens
in the body
–Easily spread from one person to
another or from one body part to
another
• Non-Infectious disease - One that
does not spread
–Rheumatoid arthritis
How is disease spread?
• People – Direct contact
–Touching
–Kissing
–Sexual contact
• Object – food poisoning
• Air, Soil and Water
• Vectors – insects: malaria
Vaccines and Treatment
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Prevention & Control
• Methods of controlling bacterial growth:
– Sterilization – heat; most can’t survive high
temperatures for long period on time.(kills
bacteria)
– Disinfectants – soaps & cleaning solutions;
sterilizes hospitals; overuse may cause bacteria
to evolve.(kills bacteria)
– Food storage – refrigeration (bacteria takes longer
to multiply at low temperatures); boiling; frying;
steaming.
– Food processing – canning (heated to high
temperature, placed into sterile jars & sealed);
chemical treatments such as salt, vinegar,sugar.
(kills bacteria)
Prevention & Control
• Vaccine – a preparation of weakend or killed
pathogens. It can prompt the body to produce
immunity to the disease.
• Immunity – the body’s natural way of killing
pathogens.
• Antibodies – compounds that block the growth &
reproduction of bacteria.
– When a bacterial infection occurs, antibiotics can be
used to fight the disease.
– Animals can suffer from bacterial diseases as well.
Ex. Anthrax – sheep to farmers & wool workers which
can lead to death. (biological warfare)
Active vs. Passive immunity
• Immunity – resistance to a particular
disease
• Active immunity - immunity that you
get because you have been exposed
to a disease
• Passive immunity – immunity that
you get because of a vaccine
T cells and B cells
• Both are white blood cells
• Regulated by helper T cells
• B cell response – defense that aids the removal
of extracellular pathogens
– B cells
• Stay in lymph nodes & organs
• Mature in bone marrow
• T cell response – destruction of intracellular
pathogen by cytotoxic T cells
• Both lymph, organs & circulation
• Occur in thymus gland (located in lower
neck & thorax)
• Act directly against certain pathogens
Koch’s Postulates
1. The pathogen must be found in an
animal with the disease and not in a
healthy animal.
2. The pathogen must be isolated from the
sick animal and grown in a laboratory
culture.
3. When the isolated pathogen is injected
into a healthy animal, the animal must
develop the disease.
4. The pathogen should be taken from the
second animal and grown in a laboratory
culture. The cultured pathogen should
be the same as the original pathogen.
Infectious v. Noninfectious
diseases
• Infectious disease - Any disease
caused by the presence of pathogens
in the body
–Easily spread from one person to
another or from one body part to
another
• Non-Infectious disease - One that
does not spread
–Rheumatoid arthritis
Mutations
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Specific vs. Nonspecific
• Nonspecific – always present, fights
off anything foreign to the body.
–2 lines of defense (1 outside, 1
inside)
• Specific – body has been exposed to
disease before (immunity to chicken
pox once you have already had the
disease)
Specific vs. Nonspecific
• 1st line of nonspecific defense
– Mucous membranes – traps it before it
can enter the body
– Skin – acts as a physical barrier
– Sweat – contains lysozyme (which
digest bacterial walls)
• 2nd line of nonspecific defense
– Inflammatory response
– Temperature response
– Proteins
– White blood cells
2nd Line of Defense cont.
• Inflammatory
response
2nd Line of Defense cont.
• Temperature response
–Disease causing bacteria don’t grow
well at high temperatures
–Normal body temperature 37º C
(98.6º F)
–> 39º C (103º F) – dangerous
–>41º C (105º F) - fatal
2nd Line of Defense cont.
• Protein complement system
– About 20 different proteins circulate in the
blood and became active when they
encounter certain pathogens by attaching to
the surface of proteins and damaging
plasma membrane.
• Interferons
– Protein is released by cells infected with
virus which causes nearby cells to produce
an enzyme that prevents viruses
Specific vs. Nonspecific
•
•
•
•
•
SPECIFIC RESPONSE
White Blood Cells – produced in bone
marrow and circulate in the blood and lymph
nodes
Macrophage – consume pathogens and
infected cells
Cytotoxic (killer) T cells – attack & kill
infected cells
B cells – label invaders for later destruction by
macrophages
Helper T cells – activate cytotoxic T cells & B
cells
SPECIFIC RESPONSE
• Infected cell has an antigen
(substance that triggers an immune
response) of an invader on its surface
• White blood cells are covered with
receptor proteins that respond to
infection by binding to specific
antigens on the surfaces of the
infecting microbes
• They recognize and bind to antigens
that match their particular shape.
Polio Panic
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Allergies
• Occur when antigens bind to
mast cells.
• Activate mast cells which
release histamines.
–Histamines produce sneezing,
runny eyes & nose
Common Antigens that cause
allergies
• Foods
• Dust
– Milk, eggs
• Antibiotics
– Penicillin
• Cosmetics
• Pollen
• Molds
• Microbes
• Chemicals in plants – poison ivy
Autoimmune diseases
• A disease in which the immune system
starts attacking body cells as if they were
pathogens.
• Affect organs and tissues in different parts
of the body.
• Graves disease, Multiple sclerosis (MS),
Rheumatoid arthritis, Systemic lupus
erythematosus (SLE), Type I diabetes
Some Autoimmune Diseases
• Rheumatoid Arthritis – exact cause is unknown,
but clear the immune system is involved.
– Involves inflammation of joint, swelling,
pain & loss of function.
• Rheumatic Fever – happens when
streptococcus bacteria causes a disease
known as strep throat.
– If left untreated, the immune system
produces antibodies that destroy
bacteria.
• Multiple sclerosis – result of destruction
by immune system of special cells that
surround nerve fibers and permit rapid
impulse transmission.
Autoimmune diseases, cont.
• Lupus – exact cause unknown, although it is
certain that both environment & genetic factors
are involved.
– Believed a genetic pre-disposition to the
disease
• Symptoms include:
– Achy joints, 100°F + fever, Arthritis,
Prolonged or extreme fatigue, Skin rashes,
Anemia, Kidney disorders
• Factors that trigger Lupus:
– Infections, Antibiotics, Ultra-violet lights,
Extreme stress, Hormones
Understanding Virus part 2
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