Transcript I. What is a virus? - Effingham County Schools

Bacteria
I.All bacteria are Prokaryotes- single
celled organisms that lack a nucleus.
Peptidoglycan
A. Cell
B. Cell
Wall
membrane
F. Flagellum
E. DNA
C. Ribosome
D. Cilia
II. Classifying Prokaryotes- all prokaryotes were once in
Kingdom Monera; now divided into 2 kingdoms
A. Kingdom Eubacteria
1. Largest group
2. Can live almost anywhere, even in your
intestines (ex. E.-coli)
3. Have cell walls
4. Unicellular
B. Kingdom Archaeabacteria
1. Live in extreme environments (ex. Methanogens
and Halophiles)
2. Have cell walls
3. Unicellular
E-coli in human intestines provides
vitamin K and some of the B vitamins
Tube Worm Symbionts/Sulfide
Oxidizing Bacteria
Tube Worms
Underwater communities thrive
without sunlight
Dead Sea
Archaebacteria- Extreme Environments
Halophiles- “Salt Lovers”
Archaebacteria- Extreme Environments
Methanogens- Live in lots of Methane
Archaebacteria- Extreme Environments
Thermophiles- Extrme “Temperature
Lovers”
III. Identifying Prokaryotes- use shape, cell wall
chemical structure, movement method of
obtaining energy and releasing energy, and
growth and reproduction.
A. Shape- 3 types
1. Bacilli-rod shaped
2. Cocci- sphere shaped
3. Spirilla- corkscrew shaped
Identify the following:
•
•
•
•
B. Cell wall structure- 2 types, identified
by Gram staining (used for prescribing
antibiotics)
1. Cell wall containing mainly
peptidoglycan appear purple =
Gram Positive.
2. Cell wall with extra outer layer of
lipids appear red = Gram Negative
Which of these bacteria are gram
positive?
C. Movement- some have flagella (long
whip-like tail), some glide on slime, some
don’t move
D. Obtaining Energy
1. Producers-(Autotrophs) make their own food
a. Examples: Cyanobacteria – carry out
photosynthesis
2.Consumers- (Heterotrophs) most prokaryotes
consume food.
E. Releasing energy- 3 ways to release energy from food.
1. Aerobes- use cellular respiration, need oxygen
2. Anaerobes- use fermentation, poisoned by oxygen
3. Facultative anaerobes- use fermentation or cellular
respiration (can live anywhere)
F. Growth and Reproduction
1. Binary fission- asexual reproduction, produces two
identical daughters cells, most bacteria do this
2. To survive harsh conditions like drought or freezing
temperatures many bacteria produce thick protective
covering around DNA called an Endospore
III. E.Q. What role do bacteria play in nature?
A. Producers- capture sun’s energy through
photosynthesis, food source for consumers and
produce oxygen
B. Decomposers- bacteria help recycle nutrients by
breaking down dead organisms; they break down
complex compounds into simpler ones.
C. Nitrogen Fixers- bacteria are the only known
organisms that can convert nitrogen into a form that
plants are able to use.
1. Some plants (legumes) even have a symbiotic
relationship in which bacteria live on their roots and
help them absorb nitrogen.
Disease causers- (pathogens)
1. Bacterial Pathogens cause disease 2 ways.
a. Heterotrophic Bacteria can break down
body tissue-Tuberculosis
b. Bacteria can release toxins (poisons).
Streptococcus- toxins cause rash called
scarlet fever.
IV. Prevention and Treatment
A. Prevent bacterial diseases with vaccines, made from
another form of the bacteria, stimulates immune system.
B. Bacterial infections are treated with antibiotics,
substances that stop bacterial reproduction.
C. Controlling bacteria- sterilization destroys bacteria by
using great heat or chemicals.
The Structure of a Eubacterium
Section 19-1
Peptidoglycan
Go to
Section:
Cell
wall
Flagellum
Cell
Membrane
DNA
Ribosome
Pilli
I. What is a virus?
A. Virus comes from the Latin word for
poison.
B. Viruses can only be seen with Electron
Microscope
C. Non-cellular particle made up of genetic
material (DNA or RNA) and a protein
coat. Not considered to be living things!
D. Parasites! CANNOT carry out life
processes unless within a host (living cell).
Usually host specific- infect only one type
of host.
Figure 19-13 Virus Structures
Section 19-3
Tobacco Mosaic
Virus
T4 Bacteriophage
Capsid
DNA
Influenza
Virus
RNA
Capsid
RNA
Capsid
Tail
Tail
fiber
Surface
proteins
Go to
Section:
Envelope
II. Viral Diseases
A. Mostly caused by virus destroying cells in
body.
B. Cause human diseases such as polio, measles,
AIDS, and the common cold
C. CANNOT be treated with antibiotics
D. Best Protection is prevention - Prevented by
safe practices or Vaccine if available.
(Vaccines must be used before infection
begins)
Rabies
SARS- flu-like virus that leads to severe pneumonia
Ebola virus- liquification of internal
organs and severe bleed out
E. Oncogenic Viruses cause cancer b/c
their DNA disrupts the normal
growth of cells
F. Retorviruses- RNA – genetic
information copied backward- from
RNA to DNA example: AIDS
III. Kinds of Viruses
A. Viruses are classified by their shape, the kind
of hereditary material they contain, organism
that they infect and reproduction.
B. The protein that covers a virus gives it its
shape.
C. Viruses are often named for the disease that
they cause (Polio) or the organ or tissue that
they infect (SARS).
IV. Viruses are generally destructive.
A. Why? Virus has to be inside a living cell to
reproduce. The cell that it reproduces in is a
host cell. A virus destroys its host cell. How?
1. Lytic Cycle -how a virus reproduces
a. When a virus enters a cell and is
active it causes the cell to make new
viruses. This will eventually destroy the
host cell.
V. Steps of Lytic Cycle
1. Attach-virus attaches to the surface of a cell
2. Inject- the hereditary material of the virus
injects itself into the cell.
3. Copy-the viral DNA takes control of the cell
and the cell begins to make new virus particles.
4. Assembles- viral particle are assembled into
new viruses
5. Release-the cell bursts open and hundreds of
new virus particles are released. These new
virus particles go on to infect other cells.
Figure 19-14 The Lytic Cycle
Attach
Section 19-3
Release
Bacteriophage
protein coat
Bacteriophage DNA
Bacterial
chromosome
Lytic Cycle
Inject
Assemble
Bacteriophage
Copy
Go to
Section:
Bacteriophage DNA
Bacteriophage protein
VI. Lysogenic Cycle- When viral DNA becomes
part of the cell’s DNA without immediately
destroying the cell or making new viruses.
A. This is a latent virus; can exist inside
host cells for many years. Can become
active at any time. Ex- Cold sores.
VII. Steps of Lysogenic cycle
1. Virus attaches to the cell and injects
hereditary material into the cell.
2. Virus becomes part of the cell’s DNA.
3. Cell divides, creating viral DNA along
with its own DNA.
4. This can happen for years until virus
becomes active
5. Then it will enter the lytic cycle
Figure 19-15 A Lysogenic Infection
Section 19-3
a) Virus attaches and invades
Bacterial
chromosome
Bacteriophage
DNA
c) Viral DNA separates from
Cell’s DNA and becomes active
c) Cell divides
Lytic
Cycle
e) Cell breaks open and
Releases virus
Prophage
d) New viruses are made
Go to
Section:
Lysogenic
Cycle
b) Virus’ DNA becomes
Part of Cell’s DNA
Bovine Spongiform
Encephalopathy
Mad Cow Disease
VIII. Prions- no genetic material (DNA nor
RNA) only protein which infects the
nervous tissue of the brain (scientists
think they cause Mad Cow Disease).