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dmitri iwanowski found what?
juice from tabacco leaves caused infections on other tabacco plants
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martinus beijerinck realized what?
tiny particles in the juice caused the infection named particle virus which means poison
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definition of viruse
non-cellular particle made of genetic material and protein that can invade living cells
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structure of viruse, what components?
- 1.core of nucleic acide (DNA or RNA)
- 2.protein coat (capsid) that surrounds nucleic acid
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bacteriophage is?
virus that infects bacteria
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diversity in structure, shapes:
rode, cubes, helix
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diversity in structure, sizes:
10-300nm(nanometer) cant see a virus unless you use SEM or TEM microscope
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virus only infect:
specific host, eg plan animal mammal bird
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viruses living characteristics
- genetic material
- replcate (reproduce)
- evolve (mutate)
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non living viruse characteristics
- non-cellular
- requires a host
- doesnt use energy (ATP)
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viral infections when:
viruses cause infections by injecting DNA/RNA into host
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viral infections 4 general phases
- infection
- growth
- replication
- lysis
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infection phase
- attaches to host cell using tail fibres
- inserts DNA into cell
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growth phase
- host RNA polymerase makes MRNA("copy") from viral DNA
- MRNA is going to take over host cell
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repication phase
virus uses host machienery(ribsomes, gongi etc) to construct DNA(nucleic acid) and capsids (protein)
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lysis phase
- host cell beomes filled with new viruses bursts(lyse)
- spreads viruses to neighbouring cells, can happen in 25 minuets
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another way lysogenic infection (2)
- infection phase=same as lytic
- growth phase is viral DNA incorporated with host DNA
- is a prophage, remains dormat for "long" time, ie HIV
- each time host cell replicates the viral DNA also replicates
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prokaryotic cells
- pro=frist
- kingdom monera, unicellular, 1-10um. yes cell walls, no membrane bound, no nucleus, no chloroplasts
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eukaryotic cells
- eu=true
- plante animalia fungi protista, uni or multi, 10-100um(micro-meter) cell walls for plants and fugi, yes membrane bound, yes nuclus, chloroplasts in plants and protists
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classification of moneras
all are prokaryotic and all are bacteri. devides into 4 plyla
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def of eubacteria
true bacteria, withininclude all bacteria cept for archaebacteria
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def of cyanobacteria
phylum of bacteria, gets energy from photosynthesis(single cell organisms)
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def of archaebacteria
group of single-celled microrganisms, have no cell nucleus or membrane bound
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def of prochlorobacteria
photosynthetic organism
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binary fission (asex)
parent cell seperates to 2 daughter cells
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conjugation (sex)
two cells get together and become one
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surface area to volume ratio
sa:v
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advantages of viruses
genetic research, gene therapy, genetic engineering
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disadvantages of viruses
disease, cancer
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preventing / treating viral infections
good hygiene, healthy lifestyle (diet exercise)
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non specific defenses
- skin: oil and sweat provides acidic environment
- cilia/mucus: traps virus
- secretion: destroy viruses
- phagocytes: viruses leading to inflammation and fever
- interferon: infected cell produce protein and interferes with virus and slows it
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specific defenses
- antibodies/immune response: produced that bind to and inactivate virus (antigen)
- immunity: active:injection of vaccine to produce antibodies passive: injection of antibodies proced in another animal
- cells mediated immunity: killer t-cells attack antigen-bearing cells and destroys them
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cell shapes:
rod, sphere, spiral
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bacterial movement
- porpelled by flagella
- lash snake =spiral forward
- glide on slimelike material
- cessile (no movement)
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energy for bacteria 2 major ways (self)
- autotrophs a) phototrophic autotrophs-obtain energy from sun (like plants)
- b) chemotrophic autotrophs-live in harsh enviro, obtain energy from inortganic molecules (hydrogen sulfige, nitrites etc)
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energy for bacteria 2 major ways (other)
- heterotrophs a)chemotrophic heterotrophs- break down organic molecules, most bacteria and animals
- b) phototrophic heterotrophs-photosynthetic but also needs organic compounds
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cell shape rod
gram positive, produce endopores
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cell shape sphere
cuckus, gros in colonies of 2 cells, non pathogenic, clumps of clustures
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cell shape spiral
posseses bipolar tufts of flagella
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gram-positive bacteria:
take up crystal violit and appear purple
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gram-negative bacteria:
take up satarine, appear red/pink, mure toxic, mure resistant to antibiotics
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endospore:
dormat form of bacteria when they are inactive
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agar:
source of food, place/habitate to live
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bacterial colony
mass of microrganismes all orginate from single parent cell. all genetically identical (clones)
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bacteria repiration
needs constant supply of energy, involves O2 and fermentation no O2
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obligate aerobes
require constant supply of O2
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obligate anaerobes
must live in absence of o2, found in soil produces toxis, canned food
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facultative anaerobes
not need o2 to live but not die without the presence of o2
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