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Bacteria & Viruses
Biology
Science Department
Deerfield High School
QUIZ TIME
Biology
Science Department
Deerfield High School
(30 MIN)
Staphylococcus aureus commonly causes boils and soft-tissue infections as well as more serious conditions
such as pneumonia or bloodstream infections. According to the Centers for Disease Control and Prevention
(CDC), 20-35% of adults and children in the United States are positive for the bacteria but do not cause
illness. Staphylococcus aureus colonization usually occurs in the armpit, groin, genital area, and, most
frequently, the inside of the nose. Most infections occur through direct physical contact of the staph
bacteria with a break in the skin (cut or scrape) or during contact with inanimate objects (such as clothing,
bed linens, or furniture) soiled with wound drainage. The most common transmission location are in
schools and hospitals.
Biology
Science Department
Deerfield High School
Warm Up
Analyze the graph:
1. Which location has the highest occurrence of resistance?
2. Based on the graph, make an inference about why penicillin resistant S. aureus is
greater in one location compared to another.
3. Why did methicillin resistance lag behind penicillin resistance? Based on the trend seen
with penicillin, what would you expect to see happen with methicillin?
Biology
Science Department
Deerfield High School
What do you already know?
 What are the differences between
viruses and bacteria?
 Are all bacteria harmful?
 When you get a cold, should you
take an antibiotic to help you get
better?
 What’s the best and easiest thing
to do to avoid getting sick?
Biology
Science Department
Deerfield High School
Bacteria
 Bacteriology is the study of bacteria
 Bacteria are prokaryotic, unicellular
organisms containing DNA and ribosomes.
 Bacteria have ALL the characteristics of living
things.
 Bacteria have the greatest percentage of the
biomass on Earth!
Biology
Science Department
Deerfield High School
Bacterial Structure
 Basic structure of bacteria:
Peptidoglycan*
Cell
wall
Flagellum
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Science Department
Deerfield High School
Cell
Ribosome
membrane
DNA Pili
Bacteria
 A rather vocal minority (less than 1%) of
bacteria cause disease in humans, animals, and
plants.
 Bacteria can cause a variety of diseases:
– Food Poisoning
– Scarlet Fever
– Tuberculosis
– Whooping Cough
– Cholera
– Bacterial Meningitis
– Syphilis
– Pneumonia
– Ulcers
– Leprosy
– Strep Throat
– Tetanus
Biology
Science Department
Deerfield High School
VIDEO CLIP:
Understanding
Bacteria
Viruses
 Virology is the study of viruses
 Viruses are “biological entities” containing either
DNA or RNA that require another cell to
survive.
 Viruses have some, but not all, of the
characteristics of life.
*So are viruses living or non-living?*
 Viruses seem to exist only to make more
viruses!
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Viral Structure
 All viruses have the same basic structure:
Capsid
(Protein coat)
Surface
Markers
Biology
Science Department
Deerfield High School
Nucleic
acid core
(DNA or
RNA)
Biology
Science Department
Deerfield High School
How Do Viruses Work?
 In order to replicate and make copies of itself,
viruses need a host cell. Any living cell can
become a host cell (human, animal, plant, and
even bacterial cells!)
 Without a host cell, viruses cannot function (i.e.are harmless!)
 Although any cell can theoretically become a host
cell, specific viruses will only infect specific cells
(EX: HIV will only infect human T cells, a part of your
immune system)
Biology
Science Department
Deerfield High School
Transmission of Viruses
 Respiratory transmission
– Influenza A virus
 Fecal-oral transmission
– Enterovirus
 Blood-borne transmission
– Hepatitis B virus
 Sexual Transmission
– HIV
 Animal or insect vectors
– Rabies virus
Biology
Science Department
Deerfield High School
How Do Viruses Work?
 Attach: The capsid of the virus binds to receptor
proteins on the surface of a host cell, tricking the
host cell into thinking it’s not a foreign invader.
 Inject: The virus then injects its genetic material
(DNA or RNA) into the host cell.
 Assemble: The viral genes are expressed, turning
the host cell into a virus-making factory.
 Repeat: The host cell eventually bursts, releasing
the hundreds of newly formed viruses to infect VIDEO CLIP:
How Viruses
Work
surrounding cells!
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
Viruses
 Viruses can cause disease in humans, animals, plants,
and even bacteria!
 Viruses can cause a variety of diseases:
– Common cold
– Hepatitis A, B & C
– Herpes
– Mononucleosis
– Warts
– Chickenpox
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– Polio
– Influenza
– Mumps
– Measles
– Viral Meningitis
– AIDS
VIDEO CLIP:
Viral Disease
Bacteria
Biology
Science Department
Deerfield High School
Biology
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Deerfield High School
Acute Virus Infection
Amount of virus
Symptoms
Virus
Biology
Science Department
Deerfield High School
Time
Poliovirus
Biology
Science Department
Deerfield High School
Poliovirus
Properties of the virus
 Enterovirus.
 Possesses a RNA
genome.
 Transmitted by the faecal
oral route.
 Cause of gastrointestinal
illness and poliomyelitis.
Biology
Science Department
Deerfield High School
Protection
 There are a few big ways to protect yourself
against pathogens (disease causing agents)
– Antibiotics (drugs to kill bacteria)
– Antivirals (drugs to treat viruses)
– Vaccination (using your body’s own immune
system to preemptively guard against attack)
Biology
Science Department
Deerfield High School
Antibiotics
 Antibiotics can only be used to treat bacterial
infections!
 Target specific structures on bacteria to kill them.
 First made from a fungus (penicillin), now most
are made artificially.
 Unfortunately, antibiotic resistance (where the
antibiotic doesn’t kill the target bacteria anymore)
is becoming a major problem.
Biology
Science Department
Deerfield High School
Antivirals
 Antivirals can only be used to treat certain viral
infections!
 Does not “kill” or disarm the virus permanently; only
shortens symptoms by 1-2 days.
 Usually only prescribed to patients with life
threatening symptoms or those that have a greater
chance of developing complications (because of their
age or they have a high-risk medical condition).
 Just like antibiotics, there is evidence of antiviral
resistance too!
Biology
Science Department
Deerfield High School
Vaccination
 Vaccines can only be used to prevent infections
(both viral and bacterial) from leading to disease.
 “Trick” your immune system to make antibodies
that destroy foreign “bodies” or particles (such as
bacteria and viruses). Your body remembers how to
make these antibodies when the real thing invades.
 Made from a weakened virus, inactivated virus, or
by using only part of the virus/bacteria itself.
VIDEO CLIP:
Vaccination
Biology
Science Department
Deerfield High School
Biology
Science Department
Deerfield High School
To Review....
 What are the differences between viruses
and bacteria?
 Are all bacteria harmful? Explain.
 When you get a cold, should you take an
antibiotic to help you get better? Why?
 What’s the best and easiest thing to do to
avoid getting sick?
Biology
Science Department
Deerfield High School
http://www.youtube.com/watch?v=
3xRttWuf3wQ
Biology
Science Department
Deerfield High School
Bacteria
Virus
Both
Biology
Science Department
Deerfield High School