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Antimicrobial agents
• Disinfectants
– 1 – Bleach
– 2 – Ammonia
– 3 – 409
– 4 – Sterile water
• Antiseptics
– 1 – Hand gel
– 2 – Iodine
– 3 – Alcohol
– 4 – Sterile water
• Antibiotics
– 1 – Streptomycin
– 2 – Erythromycin
– 3 – Tetracycline
– 4 – Sterile water
• Bacteria
– Bacillus cereus
– E. coli
– Serratia marcsens
E. coli
1
E. coli
3
2
4
Antiseptic CC
1
2
1
E. coli
3
2
4
Disinfectant CC
3
4
1
3
2
4
Antibiotic CC
Bacteria Objectives
• What are some common ways to identify
bacteria?
• Describe the structure of bacteria.
• What are some ways in which bacteria
reproduce?
• How are bacteria important to us?
How are bacteria classified?
• Domain Archaea
– Kingdom – Archaebacteria
• Lack Peptidoglycan (protein
& carbohydrate) in cell wall
• Extremophiles -
Mouth of a geyser
– Halophiles (love salt),
– Methanogens (convert H2 & CO2 into
methane gas),
– Thermoacidophiles (love acidic & hot
environments)
• First organisms to colonize primitive
earth
Domain – Bacteria
Kingdom – Eubacteria
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Eu = True
3 basic shapes
1. Bacilli – rod shaped. E. coli, Bacillus
anthracis
2. Cocci – spherical shaped. Staphylococcus
aureus, Streptococcus pyogenes
3. Spirilla – spiral shaped. Spirochette,
Syphilis
Staining properties
•
Groups Eubacteria in two groups
– Gram Staining
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Gram Positive – Gram stain purple with
Crystal violet due to thick layer of
peptidoglycan. Easier to kill with antibiotics
Gram Negative – Gram stain pink with
Safarin. Hard to kill with antibiotics due to
thin layer of peptidoglycan
Gram Positive
Gram Negative
Basic Structure
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Cell Wall,
Plasma membrane
Ribosomes
Circular DNA
Pili (hairs) for adherence to host cells
Flagella (protein) for movement,
capsule (made of polysaccharides) for
attachment.
Endospores
• Produced by Gram + (usually Bacillus
& Clostridium)
• Dormant structure to survive adverse
conditions (heat, cold, dryness).
Vegetative cell (2N), not reproductive
Bacillus anthracis
Methods of Respiration
1. Obligate aerobic bacteria must have
oxygen; (tuberculosis bacteria)
2. Obligate anaerobes die if oxygen is
present; (tetanus bacteria that causes
lockjaw)
3. Facultative anaerobes do not need
oxygen, but don’t die if oxygen is
present; (E. coli)
4. Anaerobes carry on fermentation,
while aerobes carry on cellular
respiration
Nutrition
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Heterotrophic or autotrophic
Saprophytes – feed off dead, decaying
material
Autotrophs – capable of making their own
food, photoautotroph photosynthesize, or
chemoautotrophs oxidize inorganic
compounds to produce energy (ammonia
(NH3) to form nitrite (NO2) to get energy
Reproduction
1. Asexually by binary fission
• Conjugation - Sexual reproductive
method . Two bacteria form a
conjugation bridge or tube between
them
– Pili hold the bacteria together
– DNA is transferred from
one bacteria to the other
Transformation
• Bacteria pick up pieces of DNA from
other dead bacterial cells
• New bacterium is genetically different
from original
Bacteria and Humans
• Pathogens – disease causing agents
(Pathology – science of studying diseases)
• Can produce poisonous toxins (poisons)
• Endotoxins are made of lipids &
carbohydrates by Gram - bacteria & released
after the bacteria die (cause high fever,
circulatory vessel damage…) E. coli
• Exotoxins are made of protein by Gram +
bacteria . Secreted into environment.
Clostridium tetani
To fight them:
• Antibiotics interfere with cellular functions
(Penicillin interferes with synthesis of the
cell wall; tetracycline interferes with protein
synthesis)
• Some antibiotics are made by Actinomycetes
bacteria or fungi
• Broad-spectrum antibiotics affect a wide
variety of organisms
• Bacteria can mutate and become antibiotic
resistant (often results from overuse of
antibiotics)
Helpful Bacteria:
1. Bacteria of decay
2. Nitrogen fixing bacteria (Legumes)
Rhizobium
3. Fermentation of milk products – sour
cream, yogurt, buttermilk
4. Production of cheese
5. Fermentation to produce wine,
sauerkraut, pickles
6. Mining and oil spill cleanup
Bioremediation
7. Biotechnology
Diseases caused by bacteria
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Anthrax
Botulism
Cholera
Cavities
Gonorrhea
Syphilis
Tetanus
Staph Infection (MRSA)
Food Poisoning
Lyme Disease
Diphtheria
Tuberculosis
Escherichia coli O157: H7
Leprosy
Meningitis
Strep throat
Whooping cough (Pertussis)
Food poisoning
• Results from decay of foods and
production of toxins
• 33 million people/yr get “stomach flu”
• Seafood accounts for 20 – 25% of
cases
• 33% of all raw poultry tests + for
Staphylococcus
• 1 in every 200 eggs has Salmonella
4 C’s of Food
Safety
Chill your foods
Cook your food to
the proper
temperature
Clean food and
cooking surfaces
Combat Cross
Contamination
Antibacterial Agents
• Antibiotics – organic substance that
inhibits growth in/on living material.
Penicillin
• Disinfectants – inhibits growth on a
non-living surface – bleach, ammonia
• Antiseptics– inhibits growth on a living
surface – alcohol, hydrogen peroxide
• Sterilization – high heat or chemicals
that kills bacteria
Chapter 24: Viruses
Virus Objectives
• What is a virus?
• Describe the typical structure of viruses.
• Compare/contrast lytic and lysogenic viral
cycles.
• How are viruses important to us?
• Name some viruses and their action.
Stanley (1935)
• Crystallized tobacco mosaic virus.
• Living cells don’t form crystals
• Named them virus meaning Poison
Living or non-living?
• Neither!
• It’s a nonliving
pathogenic
particle made
of a protein
coat & a
nucleic acid
Characteristic of
life
Virus
Bacteria
Growth
No
Yes
Homeostasis
No
Yes
Metabolism
No
Yes
Mutation
Yes
Yes
Nucleic acid
DNA or RNA
DNA (and RNA)
Reproduction
Only within a host
cell
Independently by cell
division
Structure
Nucleic acid w/I
capsid
prokaryotic cell
• A virion = a single virus particle
• - Small - 20 nm (polio virus) - 350 nm (small
pox virus)
- Single type of nucleic acid (RNA or DNA but
never both)
- Protein coat – capsid
- Some have envelopes (made of lipids) outside
of capsid
- Surface projections made up of glycoproteins
for attachment onto host cells
Are specific to their host
Virus Structure
• Icosahedral –
– 20 triangular faces – Polio, herpes,
chicken pox, cancer, AIDs, hepatitis,
Respiratory infections (the cold)
– Brick shaped – small pox, cowpox
– Helical – TMV, measles, rabies, influenza
• Viruses are classified by their shape and
structure
• If it contains DNA:
– Host cell may produce RNA to make more viral
proteins in host cell
– Join with host’s DNA to direct the production of
virions (viral particles)
• If it contains RNA:
– Retroviruses – such as HIV. Viral RNA uses
host’s ribosomes for viral protein synthesis
– Reverse transcriptase – viral enzyme that uses
RNA as template to make DNA. Then DNA
integrates into host DNA and then when triggered,
normal transcription occurs with the production
of RNA and translation to produce new viruses.
RNA to DNA to RNA to protein.
– Normal is DNA to RNA to protein.
Human Immunodeficiency Virus
(HIV)
A Bacteriophage
• Host is E. coli
Head
Tail w/ Tail
Fibers
The Lytic Cycle
• Get in, replicate and get out to invade other host cells –
Virulent (Disease causing)
• The cold, rubella (German measles), mumps
Release
Attachment at Receptor site
Entry
Assembly
Replication
The Lytic Cycle of Virus infection
Attaches onto host cell
Injects DNA into host cell
Reassembly of virons
Replication of Viral parts
Lysis – bursting out
Viruses that reproduce only b y the lytic cycle are called Virulent
Lysogenic Cycle
• Infect cell but do not cause disease immediately. Instead, they
incorporate their nucleic acid into host’s for extended periods of time
(sometimes years).
• May turn lytic or stay incorporated depending on conditions.
• Temperate viruses - AIDS, cold sores, chicken pox, hepatitis
Prophage
Attachment
& Injection
Integration
of nucleic acid
Cell multiplication
Prophage remains unnoticed and not transcribed. Occurs in bacterial DNA
Lytic and Lysogenic Cycles
So are we going to just sit back and let
them cause diseases in us?
Prevention:
• Antiviral drugs – not a lot since viruses aren’t living.
Basically change the receptor sites
• Vaccines – either inactivated (dead viral particles) or
attenuated (weakened or altered viral particles) are
injected into organism. Body starts the production
of antibodies and memory cells to combat viral
invaders when needed.
Diseases caused by viruses
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AIDS
The Cold
Measles
Mumps
Rubella
Chicken pox/Shingles
Small Pox
Hepatitis
SARS
The Flu
Ebola
HPV
Bird Flu
Polio
Swine flu
Polio and the Iron Lung
• Viroids – another disease causing agent but
no capsid, only the RNA. Found only in
plants
• Prion – viral proteins that are able to cause
diseases by clumping together within cell.
250 amino acids but no nucleic acid.
– Scrapie in sheep degrades nervous system.
– Mad Cow disease (Bovine spongiform
encephalopathy) in cows – puts holes into brain.
– In humans, its Creutzfeld-Jakob disease.