Download bacteria

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 eukaryotes?
 Are ALL bacteria bad??
 WHAT are viruses- are they cells? Are
they alive? What are they made of?
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?
Microbiology
The
study of single cell
organisms too small to see
with the unaided eye.
Includes BACTERIA,
Archaea, Fungi, Protists,
and VIRUSES.
Domain: Bacteria
Characteristics of 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
cells
 Most Bacteria have a cell wall!

How Big are Bacteria?
A
BACTERIUM is the size of a
PITCHER’S MOUND,
 And,
ONE CELL from your BODY
is the size of the BALLPARK!!!
BACTERIA
 Free
living
organisms.
 Multiple
shapes:
rod, sphere,
or spiral
BACTERIA, cont.




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
negative.

How does it work?
 The
purple or red stain correlates with
differences in the structure of the
bacterial cell wall
Gram-positive-
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
using the pili on the surface
How do we treat (kill) bad bacteria?

ANTIBIOTICS!!
 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.
Problems with antibiotics:

The main difficulties with antibiotics
are:
1. Allergies
2. Killing off the “good” bacteria in
our bodies
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
bacteria
What happens when we
sneeze:
“GOOD” Bacteria
 Bacteria
turns MILK into YOGURT
(Lactobacillus acidophilus) and
CHEESE.
 Bacteria help us digest our FOOD and
produce Vitamin K (Escherichia coli).
 Clean wastes from sewage water at
water treatment plants (Pseudomonas
putida).
Good Bacteria, cont.
A
natural pest killer in gardens and on
crops (Bacillus thuringiensis).
 Clean up chemicals at hazardous
waste dumps and landfills
(Methanotrophs).
 Make medicines, like ANTIBIOTICS
or using biotechnology, Human
Insulin.
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)
What determines the “type” of
bacteria?
Microscopic observation:
- Shape & Grouping (single, chain, etc)
- gram stain
- motility
 Natural Environment
 Sequence of genes (recent technology)

How do bacteria cause disease?
Attach to host cells & cause damage as
take nutrients
 Increase number and crowd out normal
cells
 Produce toxins that damage or kill cells
 Get inside normal cells and disrupt function
 Attack and damage cells in a particular part
of the body

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

How do diseases spread
(transmission to people)
How transmitted:
1. Breathe in respiratory
droplets
How to prevent:
1. Cover mouth when
cough/sneeze
2. Using infected needles
2. Use new needles
3. Introduced into wounds 3. Thoroughly clean
wounds
Cont…..
4. Insect bites
5. Sharing glasses &
utensils
6. Touching surface &
eyes,nose or mouth
7. Unprotected sex
4. Wear long pants; use
bug spray
5. Don’t share, and wash
well
6. Wash hands
frequently; don’t touch
mucus membranes to
introduce!
7. Use condom/
abstinence
8. Eating contaminated
foods or water (fecaloral transmission;
contaminated by food
handler, animal the
meat came from,
incorrect food storage,
contaminated water)
8. Wash hands before
preparing foods; correct
waste treatment; water
treatment; Don’t drink
water (only bottled!),
uncooked fruits (unless
peelable) or salads in
developing countries;
A few terms …….
Pathogen- Microorganism that causes
disease
 Infection: Occurs when microbes enter
the body and begin to multiply; this
SOMETIMES leads to
 Disease: Occurs when cells in body
damaged (as result of infection) and signs
and symptoms of illness appear.

VIRUSES

Tiny parasites
composed of:
 Genetic
material
(DNA or RNA)
 Protein
 In Some, a
Membranous
Envelope
VIRUSES, cont.



Straddle between living and not living.
Inert when outside of cells.
Thousands of different viruses in a variety of
shapes.
How are viruses classified?

Type of nucleic acid that stores the genetic
information:
 Double-stranded
(ds) DNA
 Single-stranded (ss) DNA
 dsRNA
 ssRNA
Shape of Capsid
 Presence or absence of a lipid “envelope”




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
viruses.
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.

Why are there so few antivirals available
to treat viral infections?
VIRAL DISEASES
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)

HOW DO BACTERIA AND
VIRUSES DIFFER?
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
coat.
 Antibiotics kill bacteria. Antibiotics do
NOT kill viruses. Only antivirals kill
viruses & they do NOT kill bacteria.

HOW DO BACTERIA AND
VIRUSES DIFFER, cont…
Bacteria are free living- they contain ALL
they need to grow and reproduce
themselves. One cell divides into 2
‘daughter’ cells.
 Viruses require a host cell to reproduce:
they are moochers due to their limited
genetic information. They invade a cell and
hijack its machinery to turn it into a VIRUS
FACTORY!

How do we protect
ourselves from viral or
bacterial infections?
 With
VACCINES!!
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.
Vaccines
must be given weeks or
months BEFORE you are infected
Vaccines, cont…
 2.
How do they work?
The
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
react?


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
virus.
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
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
INFLUENZA VIRUS

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 package of supplies.
Do NOT throw any of the parts away- they
will be reused!!!
 To build: Put the Neuraminidase protein (NA;
brass fasteners) and Hemagglutinin protein
(HA; pipe cleaners) into the envelope of the
influenza (flu) virus virion.

 Compare
your virus with those around you!
 How
do the virions look the same?
 How do the virions differ?
 Which do you think are examples of
antigenic drift? Why did you pick them?
Put the molecules in order by FLU season
 Are there examples of antigenic shift?
 Which do you think might be an example
of a Swine or Avian influenza virus?
Why do people need a vaccine
EVERY year for Flu?
Many different strains of Flu!
 DIFFERENT types infect people each year.
 WHY?? Influenza is one of the MOST
changeable viruses! It makes mistakes
when it copies the RNA genome.

These
result in changes (mutations)
in the HA & NA protein.
HOW does the vaccine prevent
us from catching the flu?

When get the vaccine or “catch” the flu,
our immune system “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. THAT’s how it
protects us from getting sick!
What happens when HA & NA
change?
Antibodies to the previous HA & NA will
not bind well (if at all) to stop the virus
from infecting our cells
 As a result, we need a DIFFERENT
vaccine every year to provide protection
against the current strains.

What do we call it when the HA &
NA change from year to year?

ANTIGENIC DRIFT: Small 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 infection
What happens when HA & NA are
VERY different?- ANTIGENIC SHIFT
 Abrupt,
major change in influenza virus
HA and NA
 People have little or no immunity to the
“new” virus- their immune response has
never “seen” it so they get very sick!
 Happens infrequently; Example: animal
influenza virus (like SWINE FLU or AVIAN
Flu) infects PEOPLE!