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Answer the following questions:
 Do
bacteria have a nucleus??
 Do bacteria have different shapes?
 Do bacteria have a cell membrane?
A cell wall?
 How fast and how do bacteria divide?
 Are bacteria prokaryotes or
 WHAT are viruses- are they cells?
Are they alive? What are they made
The Good,
Bad, and Ugly
The GOOD and the BAD!
 Bacteria
are both GOOD for us
and our environment and BAD for
our health.
 Can anyone name a GOOD
purpose for bacteria?
 Can anyone name a Disease
caused by bacteria?
study of single cell
organisms too small to see
with the unaided eye.
Includes BACTERIA,
Archaea, Fungi, Protists,
Kingdom Monera
Characteristics of Monerans (& bacteria!):
No membrane bound nucleus
Have cell membrane, but NOT membrane
bound organelles (like mitochondria)
Most are unicellular & very small
Ribosomes are different from ones in our
 Bacteria & most monerans have a cell wall!
How Big are Bacteria?
BACTERIUM is the size of a
 And,
ONE CELL from your BODY
is the size of the BALLPARK!!!
 Free
 Multiple
rod, sphere,
or spiral
They can be found at extreme temperatures
(boiling to freezing).
They “eat” everything from sugar to chemicals.
Classified as PROKARYOTES because they do
NOT have a nucleus.
DNA is the genetic material
What is a gram stain?
Way to see almost transparent, very small
bacterial cells under the microscope
 Used in laboratories as a first screening
mechanism to characterize bacterial
infections in people.
 Technique that differentiate bacteria into
1 of 2 groups: gram positive and gram
How does it work?
 Purple
or red stain goes with
differences in the structure of the
bacterial cell wall
cell wall traps the dye;
stain purple
Gram-negative- cell wall cannot trap
the purple dye; counter-stained red
Photomicrograph of gram+ and gram- bacteria. A) E. coli
(common gram- rod found in colon). B) Staphylococcus
epidermidis (gram + cocci found on skin C) Bacillus
cereus (gram + rod in soil).
How do bacteria reproduce?
Primarily by Binary fission- Simple & FAST!
 The
DNA is copied
 The cell & cell wall divide in the middle to form 2
identical ‘daughter’ cells.
Under optimal conditions, bacteria divide every 20
to 30 minutes.
 Occasionally, bacteria have sex (called
conjugation) to increase genetic diversity and
improve survival
 Process
involves exchange of DNA between cells
Diseases caused by Bacteria:
 Lyme
Disease (Borellia)
 Necrotizing Fasciitis (“Flesh eating”
bacteria; Streptococcus pyogenes)
 Strep Throat (Streptococcus)
 Food poisoning (Salmonella sp.,
Staphylococcus aureus)
 Meningitis (Neisseria)
How do we treat (kill) bad bacteria?
 The
first antibiotic was discovered by
Alexander Fleming in 1928. He
noticed a mold (penicillium) inhibited
growth of bacteria he was studying.
 He isolated the chemical from the
mold and named it Penicillin.
Q. If antibiotics are so effective
at killing living bacterial cells,
why don’t they hurt our cells?
A. Bacteria do not have the same
organization as our cells and
Antibiotics are SPECIFIC for the
bacteria they can kill- they are only
effective at killing certain types of
Problems with antibiotics:
The main difficulties with antibiotics
1. Allergies
2. Killing off the “good” bacteria in
our bodies
“GOOD” Bacteria
 Bacteria
turns MILK into YOGURT
(Lactobacillus acidophilus) and
 Bacteria help us digest our FOOD and
produce Vitamin K (Escherichia coli).
 Clean wastes from sewage water at
water treatment plants (Pseudomonas
Good Bacteria, cont.
natural pest killer in gardens and on
crops (Bacillus thuringiensis).
 Clean up chemicals at hazardous
waste dumps and landfills
 Make medicines, like ANTIBIOTICS
or using biotechnology, Human
Tiny parasites
composed of:
 Genetic
(DNA or RNA)
 Protein
 In Some, a
VIRUSES, cont.
Straddle between living and not living.
Inert when outside of cells.
Thousands of different viruses in a variety of
Viruses exist to reproduce!
If contacts a cell it CAN infect, the virus takes
over the cell and makes lots of copies of itself!
Viruses infect every form of life (plants, animals,
fungi, bacteria)
Viruses, cont.
Viruses do not “live”
UNLESS they are
inside a eukaryotic
cell (one of ours!).
Then, they use that
cell as their own
factory to make
millions of new
AIDS (Human Immunodeficiency Virus)
 Flu (Influenza virus)
 Chicken Pox (Varicella-Zoster Virus)
 “Kissing Disease” or Mononucleosis (EBV)
 Hepatitis (Hepatitis A, B, C, etc)
 Colds (rhinovirus, coronavirus)
 Measles (rhabdovirus)
Q. How do we treat viruses?
A. With
an antiviral.
1. This is a drug that will stop a virus
from reproducing in our cells.
2. There are VERY few antivirals.
3. Antivirals are more toxic to our
normal cells.
If antivirals aren’t the answer, how do we
protect ourselves from viral infections?
SIZE: Bacteria are much larger.
 STRUCTURE: Bacteria are much more
complex. Bacteria have a thick cell wall, a
chromosome, & ribosomes. A virus has a
small amount of nucleic acid and a protein
 Antibiotics kill bacteria. Antibiotics do
NOT kill viruses. Only antivirals kill
viruses & they do NOT kill bacteria.
Bacteria are free living- they contain ALL
they need to grow and reproduce
themselves. One cell divides into 2
‘daughter’ cells.
 Viruses are moochers- they only contain
limited genetic information. They invade a
cell and hijack its machinery to turn it into
How do we protect
ourselves from viral or
bacterial infections?
 With
Vaccines, cont…
 1.
What are they?
Part of a bacteria OR virus (or a
weakened version of the organism)
that is injected into a person.
To be most protective, a person is
usually injected multiple times
months apart.
must be given weeks or
months BEFORE you are infected
Vaccines, cont…
 2.
How do they work?
vaccine does NOT give the person
the disease.
BUT the immune system of the person
“SEES” the bacteria or virus as an
invader and REACTS to it by preparing
the weapons to fight it off.
When we get sick, it takes our immune
system several days to a week to “see” a
foreign invader (bacteria or virus) and
mount a response against it.
That’s why you feel sick!
 If you’ve been vaccinated, your body will
immediately “see” the bacteria or virus as
an invader and attack it.
 It
has the weapons to immediately fight it off
 You may NEVER know you were infected.
How does the immune response
One way the immune
response reacts is to
make specific
ANTIBODIES against a
virus or bacteria.
Later, if you are infected
with that microorganism,
the antibodies in your
body will bind to it and
stop it from infecting you.
How are Antibiotics &
Vaccines different?
 Antibiotics
kill ONLY bacteria.
 Vaccines can result in protection
against a specific bacteria OR
Which works immediately
and which does not?
 Antibiotics
start to kill the bacteria
immediately after you take them
 Vaccines require several weeks (and
possibly several shots) before they
protect against the disease
How else do we prevent disease?
Excellent Sanitation Practices!
Wash hands frequently!
 Wash foods before eating
 Careful food storage and preparation
 Treatment of human excrement to kill
infectious agents
 Clean water supplies for drinking
 Clean cuts & wounds immediately after
getting them
 Sterile practices in hospitals
Challenger Questions:
Name 2 differences between Bacteria
and our cells
Name 1 difference between Bacteria
and Viruses.
Do antibiotics work when you have a
cold (VIRUS infection)?
Name a disease caused by a
Name a disease caused by a
Name 2 good purposes for
What is one way the body fights
off bacteria and viruses?
How can we PREVENT infection
with bacteria OR viruses?
TO DO: What do antibiotics &
vaccines have in common?
Both fight infectious agents
-antibiotics ONLY fight bacteria
- vaccines can protect against
bacteria OR viruses
Antivirals= very few available; ONLY fight
specific viruses
Why do we need to be vaccinated EVERY year
against Influenza?
Build an Influenza Virus:
Working at your table, you will build an
influenza virus using the dirctions & the
package of supplies. Do NOT throw any of
the parts away!!!
 Read the directions
 Build the virus, then answer the questions
on the sheet.
Why do people get a vaccine for
Flu EVERY year?
Many different strains of Flu!
 DIFFERENT types infect people each year.
 Influenza is one of the MOST changeable
viruses! It makes mistakes when it copies
the RNA genome.
result in changes (mutations)
in the HA & NA protein.
What happens when HA & NA
Our immune response “sees” & makes
antibodies to HA & NA (it’s on the outside
of the virus!). These antibodies bind to
HA & NA to stop the virus from infecting
our cells.
 IF HA or NA have changed, antibodies
may not bind well enough to stop the
virus from infecting our cells
What do we call it when the HA &
NA change from year to year?
ANTIGENIC DRIFT: Small changes
changes in HA or NA over time.
 Parts of the HA or NA are similar, but
enough of it is different that antibodies
to “old” version no longer protect from
What happens when HA & NA
are VERY different?
 Antigenic
 An
abrupt, major change in influenza
viruses infecting humans
 People have little or no immunity to the
“new” virus- their immune response has
never “seen” it
 Happens ONLY occasionally
 Like when an animal influenza virus (like
SWINE FLU or avian influenza) infects
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