viruses. i. viruses 1. they are nonliving i.viruses are not cells… they carry on no life function...
DESCRIPTION
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. prokaryotics cells ,000 nm eukaryotics cells 10, ,000 nm viruses nm 1 nanometer (nm) = one billionth of a meter viroids nm Rabies virusTRANSCRIPT
Viruses
I. Viruses 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
viableii. 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 infecti. Rabies virus & Polio virusii. Adenovirus (the Common Cold): infects the
adenoid tissue in throat and nasal cavity3. Viruses are small
i. Smaller than the smallest known cellii. about 100 times smaller than bacteria.
prokaryotics cells200-10,000 nm
eukaryotics cells10,000-100,000 nm
viruses50-200 nm
1 nanometer (nm) = one billionth of a meter
viroids5-150 nm
Rabies virus
4. Viruses are classified by a number of different characteristics:
a. Shapeb. Nucleic Acid content – DNA or RNAc. Presence or absence of an “envelope”d. Type of host it affectse. How it is transmittedf. Vectors-
i. 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.
II. Types of Viruses1. DNA viruses
i. They will not change much overtime
ii. DNA tends to stay stablei. Ex.: Adenovirus (common
cold) / Poxviruses (small pox)
2. RNA virusesi. 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 Structure1. Made of mainly Protein
1. Proteins on surface help viruses attach to cells
2. Has a Coat called Capsida. Contains the Nucleic acid Coreb. either DNA or RNA
i. RNA Viruses= HIV destroys white blood cells
ii. DNA Viruses= Cold sores and Smallpox
3. Some viruses have an Envelope
a. an additional coatingb. enhances the viruses’ ability to
enter an organism or host cell
capsid
DNA
tail sheath
tail fiber
V. Outbreaksi. Virology—the study of viruses (and virus-like agents) ii. Epidemic—when cases of a given disease substantially exceed
“expected” cases of that particular diseaseiii. Pandemic—occurs when an epidemic spirals out of control,
spreading across large regions (i.e. a continent or worldwide)VI. Treatments
i. Antibiotics DO NOT treat viral infections, only bacteriaii. Vaccines— are deactivated viruses that trick the immune
system into thinking there has already been an infection.i. Vaccines stimulate antibody productionii. Antibodies mark which items in the body get destroyediii. 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. BacteriaA. Belong to Two Kingdoms
1. Archaebacteriai. live in extreme environmentsii. 02 free environmentiii. Extremophiles
2. Eubacteriai. The most commonii. Live in non-extreme
environmentiii. Some are parasites
B. You can find bacteria in fossils
C. Characteristics:1. Unicellular2. May live in colonies3. Prokaryotes
1. They have no nucleus2. Their DNA is floating freely in the cell
4. Autotrophs (Producers) i. Photosyntheticii. Chemosynthetic
5. Heterotrophic (consumers)1. Feed off of organic material outside of themselves
flagellumpili
plasmid
cell wall
chromosome
plasmamembrane
D. Bacterial Structure1. 3 basic shapes
i. rod (bacillus)ii. round (coccus/ cocci)iii. Spiral (spirilium)
2. 2 types of cell extensionsi. pili (pilus) –hair-like structures that helps
them stick to surfaces and each otherii. flagella –allows some bacteria to move
3. Plasmidi. small circle of DNA (a single chromosome)
4. Capsule i. is an external protective layer that keeps it
from being destroyed5. Cell walls – Similar to plants
i. Penicillin (antibiotic) stops the formation of cell walls (Helps destroy bacteria)
Spirochaeta : spiral
Enterococci: round
Lactobacilli: rod-shaped
E. Adaptations1. Bacteria live in various habitats and
have several adaptationsi. They can breakdown dead matter.
i. Prevents buildup of deceased materialii. Some can use poisonous substances
as food (ex. Oil) Bioremediationiii. They can exist in extreme hot/cold
2. High rate of Mutualismi. The relationship between two species
with both getting benefits The bacteria in your intestines help to
breakdown food faster.3. Some need an O2 environment =
aerobic (Ex. Tuberculosis – affects lungs)4. Some can’t live in O2 environment =
anaerobic (Botulism -food poisoning)
II. Bacteria Life CycleA. Asexual Reproduction
1. Binary Fissioni. Reproduce (Mitosis) by
dividing into two cellsii. Can happen very quickly
B. Sexual Reproduction1. 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
III. DefenseA. 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: overuse underuse misusei. 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.
IV. Good Bacteria and Bad BacteriaA. 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 diseasesi. Done by invading tissues or creating toxinsii. EX. E-coli and streptococci