af Erica Drysdale 6 år siden
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-one single protein -NO nucleic acid -Transmissible Spongiform Encephalopathies (TSE) ----slow fatal neurodegenerative disease ***brain tissues develop holes scrapie --> goats mad cow and kuru --> people
-small single strand RNA -NO protein coat -cause disease in plants
"obligate intracellular parasites" -need host cell for protein synthesis machinery -very small -Structure:
Infections
Persistent
years of lifetime
Latent
periods of latency with potential for reactivation to productive infection
Herpes (cold sores) Varicella zoster (chicken pox --shingles)
Chronic
virons constant release in low levels = productive
Hep. B HIV
Acute:
rapid onset short duration
Genome Replication:
Retroviruses --> reverse transcriptase to transcribe
RNA --> RNA replicase
RNA/Retro rapidly undergo antigenic drift
mechanism for variation in viruses (accumulation of mutations)
DNA --> DNA polymerase
DNA will NOT make mistakes
Eukaryotes
Helminths
Worms
3) Insect Bites transmit tiny thread like worms
River Blindness --black fly
Elephantiasis --mosquito
2) Burrow through skin (bare feet, poor sanitation)
Schistosomiasis
1) Ingestion
feces-->pinworm, asariasis raw meat-->tapeworm
Protozoa
unicellular, heterotrophs -lack cell wall -motile
Toxoplasmosis --cysts ingested
pregnant women kitty litter
REMEMBER: protozoan cysts can withstand stomach acid **essential for fecal-oral route
Giardiasis --fecal-oral-cyst form
beaver fever
Malaria --Mosquito vector
Fungi
Cause Human Illness
3) Mycoses -fungal infections grow on/in body
Lung infection --**worse on immunocompromised
Candida (mucous membrane) --vulvovaginal, oral thrush
Dermatophyte --Ringworm,Jock itch
2) Allergy/Asthma -hypersensitivity
1) Intoxication -toxins poisonous
Heterotrophs -cell wall CHITIN -Ergosterol in cell membrane -target for antibiotics
Morphological Forms:
Mushrooms -multicellular -reproductive structures:
**obtain nutrients by secreting digestive enzymes
Moulds -multicellular
Yeasts -unicellular
Algae
Autotrophs -cell wall made of cellulose -toxins--> paralytic shellfish poisoning
Prokaryotes
Bacteria
Chapter 20 Part 1
Narrow Spectrum
target a specific group **must know exact target
Broad Spectrum
effective against >1 group of bacteria **kills microflora
Selective Toxicity
kills microbes --> low toxicity to humans
Chapter 4 Growth
Factors Affecting Growth
Expectations
Endospores --> bacillus and clostridium
Myobacteria --> waxy, lipid cell wall
Mycoplasma --> lack cell wall
Nutrients
Fastidious
cannot make things from scratch
Versatile
can make things from scratch
Salt
Extreme Halophiles
require high salt
Halophiles
require salt
Halotolerant
small amount of salt
pH Requirements
Alkaliphiles
pH >8 (high pH)
Acidophiles
pH <5 (low pH)
Neutrophiles
grow best pH~7
Oxygen Requirements
Microaerophile
needs small amounts of oxygen
contain enzyme to detoxify (only have a few enzymes to break down oxygen)
Aerotolerant Anaerobe
indifferent to oxygen -doesnt care either way
contain enzyme to detoxify
Obligate Anaerobe
must have NO oxygen (poisoned by oxygen)
does NOT contain enzyme to detoxify -endospores survive
Facultative Anaerobe
"make do" without oxygen but grow better with
contain enzyme to detoxify
Obligate Aerobe
MUST have oxygen
Contain enzymes to detoxify
Temperature
psychro/meso/thermo
Calculating Growth
#=initial # * 2^(#of doublings)
Generation Time
amount of time it takes to double
Binary Fisson
splitting into 2
Chapter 3 Structure
Appendages
Sex Pilus
Conjugation (transfer of plasmid DNA)
Fimbriae
attachment to surfaces
Flagellum
Mobility and enables chemotaxis
Gram-Negative
-thin PTG wall -outer membrane -LPS-endotoxins -porins
Gram-Positive
-thick PTG wall (many layers)
Cell Wall
-PTG -specific to bacteria -protection against lysis -essential for survival
Chromosomal DNA
-basic genome -all contain this DNA
Ribosomes (70s)
-cannot survive without protein synthesis (70s)
Plasmid DNA
-Contains genes resistant to antibiotics
Cell Membrane
-regulates the entry and exit of substances -*transport and receptor proteins*
Archaea
