Download Unit5B Viruses-Bacteria Online1

Viruses
Viruses
I.
1.
They are Nonliving
i. Viruses are NOT cells… they carry
on no life function on their own

they can be stored for years and still be
viable
ii. Viruses do NOT replicate themselves

this happens only after invading a
living Host Cell
iii. Unprecedented diversity


A virus for every species
RNA viruses lack any error
proofreading when being copied –
leads to different forms of the same
viruses that the body does not
recognize
2. Named after the disease they cause or the
tissue they infect
i. Rabies virus & Polio virus
ii. Adenovirus (the Common Cold): infects the
adenoid tissue in throat and nasal cavity
3. Viruses are small
i. Smaller than the smallest known cell
ii. about 100 times smaller than bacteria.
Rabies
virus
1 nanometer (nm) = one
billionth of a meter
eukaryotics cells
10,000-100,000 nm
prokaryotics cells
200-10,000 nm
viruses
50-200 nm
viroids
5-150 nm
4. Viruses are classified by a number of
different characteristics:
a.
b.
c.
d.
e.
f.
Shape
Nucleic Acid content – DNA or RNA
Presence or absence of an “envelope”
Type of host it affects
How it is transmitted
Vectorsi. any organism or object that carries or transmits
disease causing organisms
ii. Ex. needles, worms, water, mosquitoes, etc.
g. Attachment process
i. they can only attach to specific cells or cell types.
Types of Viruses
II.
1.
DNA viruses
i.
They will not change much
overtime
ii. DNA tends to stay stable
i.
2.
Ex.: Adenovirus (common
cold) / Poxviruses (small
pox)
RNA viruses
i.
They will change often b/c
they do not proofread errors
when the RNA gets copied.
i.
Ex. HIV (causes AIDS)/
Influenza (Swine flu)
III.
Virus Structure
1. Made of mainly Protein
1.
Proteins on surface help viruses
attach to cells
2. Has a Coat called Capsid
a. Contains the Nucleic acid Core
b. either DNA or RNA
RNA Viruses= HIV destroys white
blood cells
ii. DNA Viruses= Cold sores and
Smallpox
capsid
D
N
A
tail sheath
i.
3. Some viruses have an
Envelope
a. an additional coating
b. enhances the viruses’ ability to
enter an organism or host cell
tail fiber
V.
Outbreaks
i.
ii.
Virology—the study of viruses (and virus-like agents)
Epidemic—when cases of a given disease substantially exceed
“expected” cases of that particular disease
iii. Pandemic—occurs when an epidemic spirals out of control,
spreading across large regions (i.e. a continent or worldwide)
VI.
Treatments
i.
ii.
Antibiotics DO NOT treat viral infections, only bacteria
Vaccines— are deactivated viruses that trick the immune
system into thinking there has already been an infection.
i. Vaccines stimulate antibody production
ii. Antibodies mark which items in the body get destroyed
iii. Antibodies will “remember” a virus
iv. Now when the body is exposed to the harmful virus
again the antibodies will be made faster to kill the virus.
I.
Bacteria
A. Belong to Two Kingdoms
1. Archaebacteria
i. live in extreme environments
ii. 02 free environment
iii. Extremophiles
2. Eubacteria
i. The most common
ii. Live in non-extreme
environment
iii. Some are parasites
B. You can find bacteria in
fossils
C.
Characteristics:
1.
2.
3.
Unicellular
May live in colonies
Prokaryotes
1.
2.
4.
They have no nucleus
Their DNA is floating freely in the cell
Autotrophs (Producers)
i. Photosynthetic
ii. Chemosynthetic
5.
Heterotrophic (consumers)
1.
Feed off of organic material outside of themselves
plasma
membrane
chromosome
cell wall
plasmid
pili
flagellum
Lactobacilli: rod-shaped
D.
Bacterial Structure
1. 3 basic shapes
i. rod (bacillus)
ii. round (coccus/ cocci)
iii. Spiral (spirilium)
2. 2 types of cell extensions
Enterococci: round
i. pili (pilus) –hair-like structures that helps
them stick to surfaces and each other
ii. flagella –allows some bacteria to move
3. Plasmid
i. small circle of DNA (a single chromosome)
4. Capsule
i. is an external protective layer that keeps it
from being destroyed
5. Cell walls – Similar to plants
i. Penicillin (antibiotic) stops the formation
of cell walls (Helps destroy bacteria)
Spirochaeta : spiral
E.
Adaptations
1.
Bacteria live in various habitats and
have several adaptations
i.
They can breakdown dead matter.
i.
Prevents buildup of deceased material
ii. Some can use poisonous substances
as food (ex. Oil)  Bioremediation
iii. They can exist in extreme hot/cold
2.
High rate of Mutualism
i.
The relationship between two species
with both getting benefits

3.
4.
The bacteria in your intestines help to
breakdown food faster.
Some need an O2 environment =
aerobic (Ex. Tuberculosis – affects lungs)
Some can’t live in O2 environment =
anaerobic (Botulism -food poisoning)
II.
Bacteria Life Cycle
A. Asexual Reproduction
1. Binary Fission
i.
Reproduce (Mitosis) by
dividing into two cells
ii. Can happen very quickly
B. Sexual Reproduction
1. Conjugation
i.
One bacteria transfers all or
part of its chromosome
(DNA) to another cell
through pilli that connects
the two cells
ii. Results in bacteria with new
genetic composition
Defense
III.
A.
How do Antibiotics work?
1. They stop the creation (synthesis) of bacterial cell
walls or cause the cell walls to break apart.
2. Antibiotics interfere with the functions (metabolic
processes) of bacterial ribosomes (i.e. protein
synthesis).
3. Unlike bacteria, viruses don’t have cell walls or
ribosomes, so antibiotics have no effect on them.
B. Bacteria are gaining resistance to
antibiotics through:



i.
overuse
underuse
misuse
A bacterium may already have an gene
(DNA) for antibiotic resistance on the
plasmid
ii. A copy of the plasmid is transferred
through conjugation.
iii. Resistance quickly spreads through
many bacteria.
Good Bacteria and Bad Bacteria
IV.
A.
There are good and bad bacteria
1. Good bacteria are used to help fight disease/
create food (cheese)/ and deal with pollution
i.
EX. Lactobacillus acidophilus, Dehalococcoides ethenogenes
2. intestinal bacteria make up approximately 95% of
the total number of cells in the intestinal tract.
3. Bad bacteria cause life threatening diseases
i. Done by invading tissues or creating toxins
ii. EX. E-coli and streptococci