MICROBIOLOGY

lambblueearthΒιοτεχνολογία

29 Σεπ 2013 (πριν από 3 χρόνια και 6 μήνες)

65 εμφανίσεις

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?


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
.

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
cells


Bacteria

& most monerans 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?


Purple or red stain goes 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

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?


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
.


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

Problems with antibiotics:


The main difficulties with antibiotics
are:


1. Allergies


2. Killing off the “good” bacteria in
our bodies

“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.


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.


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.


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)

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?

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 are moochers
-

they only contain
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

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:

1.
Name 2 differences between Bacteria
and our cells

2.
Name 1 difference between Bacteria
and Viruses.

3.
Do antibiotics work when you have a
cold (VIRUS infection)?

4.
Name a disease caused by a
bacteria.

5.
Name a disease caused by a
virus.

6.
Name 2 good purposes for
Bacteria.

7.
What is one way the body fights
off bacteria and viruses?

8.
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

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 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.


These result in changes (mutations)
in the HA & NA protein.


What happens when HA & NA
change?


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
infection


What happens when HA & NA
are VERY different?


Antigenic Shift
:


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
PEOPLE!