-
complete elimination of all lifeforms, including endospores
sterilization
-
elimination of all vegetative cells of pathogens
disinfection
-
what does disinfection NOT kill?
non-pathogenic cells
-
reduction of pathogens to a safe level
sanitization
-
how do safe levels vary in sanitization?
from pathogen to pathogen
-
disinfectants that are approved for use on the body
antiseptics
-
specific way the method accomplishes killing or inhibition
mechanism of action
-
what are the three most common mechanisms of action?
damage to proteins and dna, altering of membrane permeability, and slowing down metabolism
-
what are some methods that work by damaging proteins and dna?
wet heat, heavy metals, radiation, etc
-
what methods work to alter membrane permeability?
phenolics and quats
-
phenolics and quats do what to a membrane?
insert themselves into the membrane and form holes that ruin membrane integrity
-
what are some methods that slow down metabolism?
bacteriostatic - cold and dessication
-
methods of controlling bacteria can be one of what two things?
physical or chemical
-
how do physical methods of control work?
altering the physical environment
-
what are some physical methods of control?
heat, cold, radiation, desiccation, osmotic pressure, filtration, soaps/detergents
-
how do chemical control methods work?
employ some kind of chemical attack
-
what are some chemical methods of control?
phenolics, halogens, alcohols, heavy metals, aldehydes, quats, peroxides
-
mechanism of action of moist heat
denatures proteins
-
what is moist heat?
hot water or steam
-
what is an example of moist heat?
boiling, autoclaving, pasteurization
-
endospores survive boiling, especially under what amount of time?
10 minutes
-
how do autoclaves work?
use steam under pressure to denature proteins
-
what is the time/temp combo most used in autoclaves?
121 celsius for 15 minutes (15 psi)
-
what is the target organism for the pasteurization of milk?
coxiella burnetii
-
what are some other autoclaves?
home and commercial canners
-
what are commercial canners called? what is their process called?
retorts; commercial sterilization
-
what is the target organism of commercial canning?
endospores of clostridium botulinum
-
home canners (pressure cookers) should be operated at what time/temp combo?
121 celsius for 15 min (15 psi)
-
what is the most common cause of botulism?
inadequately processed hoe canned foods
-
mechanism of action of dry heat
kills by burning
-
what is dry eat?
fire or hot air
-
what is an example of dry heat?
incineration
-
dry heat is less/more effective than moist heat at the same temperature?
less
-
what is the most common time/temp combo used to sterilize with hot air?
160 celsius for 120 min
-
what is dry heat used on?
glass and metal
-
some hospitals have their own what?
incinerator for biological wastes
-
what happens to the carcasses of cattle effected with anthrax?
incinerated to make sure endospores are destroyed
-
what causes anthrax?
bacillus anthracis
-
what is a method of dry heat used in lab?
flaming loops
-
mechanism of action of cold
slows metabolism
-
what is an example of cold?
freezing, refrigeration
-
cold temperatures are bacteriostatic or bacteriocidal?
bacteriostatic
-
what is the growth of mesophiles inhibited by?
refrigeration temperatures
-
what mesophile grows well at refrigeration temperatures?
listeria monocytogenes
-
mesophiles include most what?
pathogens
-
what grows at refrigeration temperatures? what are they responsible for?
psychrotrophs, refrigerated food spoilage
-
what is the most common spoilers of raw meats?
psuedomonas fragi
-
mechanism of action of radiation
damages dna
-
what is an example of radiation?
ionizing and non-ionizing
-
what radiation is ionizing?
gamma rays, x rays, electron beams
-
what radiation is non-ionizing?
UV
-
ionizing radiation is energetic enough to do what?
knock electrons off of atoms
-
what rays are used for sterilizing packaging materials?
gamma rays and xrays
-
what is the most commonly used source of gamma rays?
cobalt-60
-
UV radiation is useful for what?
surface air treatment (hospitals)
-
what is the most effect wavelength of uv light?
260nm
-
what is 260nm the bst wavelength?
dna absorbs uv rays best at this wavelength
-
what does UV cause?
thymine dimers
-
what does the formation of thymine dimers do to dna?
changes shape of dna molecule, which causes enzymes that make dna copies to malfunction
-
hospitals may have what used to disinfect?
UV lights to disinfect the air
-
the biological hood contains what?
UV light and HEPA filter
-
mechanism of action of dessication
slows metabolism
-
what is an example of dessication?
dehydrating or drying foods
-
dessication is bacteriostatic or bacteriocidal?
bacteriostatic
-
how does desiccation work?
all organisms require water, when moisture becomes too low enzymes no longer function and metabolism stops
-
foods with what concentration of water inhibit microbial growth?
less than 20%
-
foods that inhibit all microbial growth are resistant to what?
spoilage
-
fungi tolerate low water levels better than what?
bacteria
-
molds may grow on what foods? why?
cheese and bread, they grow in dry areas better than bacteria
-
mechanism of action of osmotic pressure
draw water out of cells and cause plasmolysis
-
what is an example of osmotic pressure?
high levels of sugar/salt in foods like jellie, james, honey, syrup, salty meat
-
salted foods may be vulnerable to what pathogen?
staphylococcus aureus
-
staphylococcus aureus grows in salt concentrations of what?
more than 7%
-
mechanism of action of filtration
removes microbes
-
what is an example of filtration?
operating rooms, biological safety hoods, membrane filters
-
HEPA filter
high-efficiency particulate air filters
-
what are HEPA filters used for?
to filter air
-
to be a HEPA filter you must catch a minumum of which particles?
99.97% of 0.3 micrometers (most bacteria are >1 micrometer)
-
mechanism of action of soaps/detergents
decrease surface tension
-
what does the decrease of surface tension cause?
microbes are allowed to be lifted up and carried off
-
soaps and detergents have little or no what?
germicidal action
-
rather than kill microbes what do soaps/detergents do?
make it easir to rub and rinse away microbes on surfaces
-
terms like "sanitizer", "disinfectant", "antimicrobial" cannot be put on labels until when?
approved by meeting government regulations
-
antimicrobial products are regulated by who when products are meant to be used on environmental surfaces?
EPA
-
antimicrobial products are regulated by who when products are more for use on the body or could enter the body?
FDA
-
EPA
environmental protection agency
-
FDA
food and drug administration
-
EPA calls their products what? FDA calls their products what?
pesticides, drugs
-
what microorganisms are most resistant to chemicals? why?
endospores and mycobacteria; waxy mycolic acid coat
-
what organisms are generally more resistant than bacteria to chemicals?
eukaryotic
-
bacteria are generally more resistant than who to chemicals?
viruses
-
list major groups of microorganisms from most resistant to least resistant
- endospores
- mycobactera
- cysts of protozoa
- vegetative protozoa
- gram-negative bacteria
- fungi (including fungal spores)
- non-enveloped viruses
- gram-positive bacteria
- enveloped viruses
-
some viruses are surrounded by a membrane called what?
envelope
-
mechanism of action of phenolics
disrupt cell membranes
-
what is an example of a phenolic?
thymol, triclosan
-
phenolics are effective against what?
mycobacteria
-
thymol is an active ingredient in what?
listerine
-
triclosan is the active ingredient in what?
antibacterial handsoaps and detergents
-
antibacterial liquid handsoaps in the lab contain what?
triclosan
-
mechanism of action of halogens
inhibit proteins
-
what is an example of a halogen?
fluoride, chlorine, hypochlorite (HOCl), iodine, iodophors
-
fluoride is in what?
toothpaste (~1000ppm)
-
chlorine is used for what?
treat drinking water (~1ppm)
-
what is hypochlorite an active ingredient in?
bleach (5% hypochlorite)
-
what is iodine useful for?
prepping skin before an injection
-
what are iodophors?
iodine combined with detergents
-
what are iodophors useful for?
prepping areas before surgery (disinfect and have cleaning action)
-
mechanism of action of alcohol
inhibit proteins, dissolve lipids
-
what is an example of an alcohol?
ethanol
-
isoproponal is a common what?
household disinfectant (rubbing alcohol)
-
ethanol is often used for what?
injection prep
-
what do we use ethanol in lab for?
soaking metal spatulas
-
what happens after spatulas are soaked in ethanol in lab?
passed through flame to burn off alcohol
-
what is the most effective concentration of ethanol or isoproponal?
70% (some water is required in order to denature proteins)
-
mechanism of action of heavy metals
inhibit proteins
-
what is an example of a heavy metal
silver, copper
-
what was traditionally place on eyes of newborns?
drops of 1% silver nitrate
-
what was silver nitrate used to prevent? how would that be passed to the child?
neisseria gonorrhoeae infections, passed during birth
-
what antibiotic is used today to place on eyes of newborns?
erythromycin
-
why is erythromycin used today in newborns?
the rise in chlamydia trachomatis eye infections, silver nitrate couldn't effectively kill it
-
what is copper sulfate used for?
treat swimming pool water (prevent algal growth) and grapes (prevent fungal growth)
-
mechanism of action for aldehydes
inhibit proteins
-
what is an example of an aldehyde?
formaledhyde
-
why is aldehyde a potential sterilant?
effect even against endospores
-
aldehydes are also potential what?
carcinogens
-
what is probably the most effective groups of disinfectants? why aren't they used often?
aldehydes, suspected carcinogens
-
what have solutions of formaldehyde traditionally been used for?
to embalm bodies or preserve biological specimens
-
embalming solutions contain what percent of formaldehyde?
15%
-
mechanism of action of quats
disrupt cell membranes
-
what an example of a quat
benzalkonium chloride
-
what is benzalkonium chloride listed as on labels?
alkyl dimethy benzyl ammonium chloride
-
quats are toxic/nontoxic?
non toxic
-
quats can be used in sensitive areas such as what?
eyewash solutions
-
quats are active ingredients in what?
lysol, fantastik, household sanitizers
-
quats are the active ingredient in what in lab?
lysol
-
mechanism of action of peroxides
cause various oxidation reactions
-
what is an example of a peroxide?
hydrogen peroxide (h2o2)
-
what peroxide is a common household disinfectant?
hydrogen peroxide
-
what is a common acne topical medication?
benzoyl peroxide
-
describe bacterial chromosomes and describe eukaryotic chromosomes
singular, circular; multipl, linear
-
E. coli has how many basepairs? how many genes? is this common for bacteria?
4.6 million; 4,300; yes
-
human dna contains how many base pairs? how many genes?
3.4 billion; 20,000
-
bacteria also contain what in their dna?
plasmids
-
plasmids have genes for what?
toxins or resistances to antibiotics/disinfectants
-
what are some processes involving dna?
replication, transcription, translation, genetic recombination
-
dna replication
copy of chromosome is made
-
transcription
rna is made using information in dna
-
translation
proteins are made using information in rna
-
genetic recombination
segments of dna are transferred from one chromosome to another
-
where does dna replication occur?
cytoplasm, specifically the nucleoid
-
where does dna replication occur in eukaryotes?
nucleus
-
bacterial chromosomes have a single origin of replication, which is where?
a specific sequence of nucleotides recognized by the replication enzymes
-
eukaryotic chromosomes are larger than bacterial chromosomes so they have how many origins of replication?
multiple
-
what happens once replication is finished?
new chromosome copies remain attached to proteins in cell membrane, this allows copies to seperate during binary fission
-
how does dna replicate in eukaryotes?
spindle fibers move chromosomes around during mitosis
-
major enzymes involved in dna replication
dna helicase and dna polymerase
-
what does dna helicase do?
uncoils the dna helix and seperates the two strands
-
what does dna polymerase do?
lays down the new nucleotides and forms new strands of dna
-
what are the short lengths produced on discontinuous dna strands are called what?
okazaki fragments
-
what is rna used to make?
proteins
-
where does transcription occur?
cytoplasm
-
where does transcription occur in eukaryotes?
nucleus
-
what is the major enzyme responsible for bacterial transcription
rna polymerase
-
how does rna work to transcribe a gene?
rna polymerase binds to the dna at the promoter, then seperates the two strands of dna and begins reading dna in one strand, it attaches rna nucleotides according to the nucleotide sequence in dna, and the rna molecule lengthens
-
bacterial dna contains no what?
introns
-
what are introns?
segments of rna that must be removed in order to produce the proper protein later during translation
-
do eukaryotic rna contain introns?
yes
-
why are there no introns in bacterial rna?
there is no time to remove introns
-
how fast does rna work?
translation usually begins before transcription ends (before rna is finished being made, ribosomes are already grabbing it and trying to make proteins using the information already there)
-
where does transcription and translation occur in eukaryotes?
nucleus, cytoplasm
-
what are the major structures for bacterial translation?
ribosomes
-
what are ribosomes made of?
part protein and part RNA
-
bacterial cells usually have how many ribosomes?
thousands
-
ribosomes read information in rna how many nucleotides at a time?
three
-
what are three sets of nucleotides called?
codons
-
what does a single codon indicate?
a specific amino acid that will be added to the protein
-
what specific codon does translation begin at?
AUG or the start codon
-
how are new amino acids delivered?
by pieces of tRNA (transfer rna)
-
ribosome continues reading codons and adding amino acids until when?
it reaches one of the three stop codons, then the ribosome disnegages and the new protein is released
-
what are the three types of rna that participate in translation?
mRNA, tRNA, and rRNA
-
mRNA
contains the dna message and is the piece of RNA that the ribosome reads
-
tRNA
delivers the new amino acids to the ribosome
-
rRNA (ribosomal)
forms part of the ribosome (the rna part)
-
why are bacteria able to adjust their metabolism more quickly than eukaryotic cells when the environment changes?
bacterial transcription and translation aren't seperated by compartments
-
what is a mutation?
change in the nucleotide sequence of dna
-
what are mutations caused by?
spontaneous or mutagens
-
spontaneous mutations are due to what?
errors made by dna polymerase during replication
-
what are mutagens?
chemical or physical agents that cause dna polymerase to make mistakes
-
how can mutations be repaired?
dna polymerase has a self-checking ability and other enzymes (repair enzymes) patrol dna and detect unusual shapes
-
what may mutagens be?
radiation or chemicals
-
what is a radiation mutagen?
gamma rays, xrays, uv
-
what is a chemical mutagen?
aflatoxins, ethidium bromide, 5-bromouracil
-
bacteriocidal uv lamps have what peak wavelength?
260 nanometers
-
how do chemical mutagens cause mutations?
by changing the shape of the dna molecule
-
what mold produces aflatoxins?
aspergillus flavus
-
what are the most carcinogenic naturally produced substances known?
aflatoxins
-
what are the most commonly contaminated foods by aflatoxins?
peanuts, corn, and wheat
-
what is ethidium bromide used for?
stain gels after electrophoresis
-
what is gel electrophoresis used for?
to seperate dna fragments during dna fingerprinting
-
where does the ethidium bromide bind during gel electrophoresis?
to the dna and is used to located where the bands of dna occur
-
where is 5-bromouracil commonly used? what for?
in lab to cause mutations for experimental research
-
where has 5-bromouracil been used out of labs?
to treat cancer
-
what enzymes are available to prevent/repair mutations?
dna polymerase, photolyass, and endonucleases
-
dna polymerase has what special function?
a proof-reading function
-
what is photolyase activated by? what does it do?
light, break thymine diners and allow thymines to reattach to their original bases
-
what does endonuclease do?
cuts out affected nucleotides after thymine dimers and allows other enzymes to replace them
-
what test is used to determine if a chemical is a mutagen?
the ames test
-
what does the ames test use?
a his (histidine negative)
-
what histodine negative does the ames test use?
salmonella typhimurium
-
how does the ames test work?
- chemical being tested and rat liver extract are added to a tube containing salmonella typhimurium
- time is permitted for mutations to occur and then the mix is plated on an agar without histidine
- growth on agar means that mutations occured
-
how would a mutagen survive on an agar?
most cells die due to lack of histidine in the media, but mutagens will now be allowed to produce their own histidine and will survive
-
why is rat liver extract used during the ames test?
chemicals are not mutagenic in their original form but converted to mutagenic compounds by liver enzyme
-
the ames tests does not just test one compound. why?
enzymes in rat liver produces a variety of molecules when mixed with original chemical, so it is a test of the original compound and all of its variations
-
what is genetic recombination?
exchange of dna between two chromosomes
-
what does bacterial recombination require? why?
dna travel from cell to cell because bacterial chromosomes are singular
-
how do movement of bacterial dna occur?
transformation, conjugation, and transduction
-
what is transformation?
update of naked dna from the environment
-
what is conjugation?
direct transfer of dna from one cell to another
-
what is transduction?
transfer of dna from one bacterial cell to another by a bacteriophage (virus)
-
how can transformation be improved in a lab?
adding chemicals like mild detergents or passing an electric current through the solution (electroportation)
-
what do the methods of lab transformation do to the membrane?
ruin it, but not enough to kill it hopefully allowing fragments of dna to pass through
-
how does conjugation occur?
through direct contact
-
how do gram-negative bacteria conjugate?
using pilus to attach to the receiving cell and reel it into contact
-
what species allow conjugation?
genetically equipped with necessary structures
-
what is passed during conjugation that would give off various resistances?
plasmids
-
why are plasmids so highly populated?
copies are only given off during conjugation so both cells have this plasmid genes and they can pass them onto other cells
-
what is one common conjugation plasmid?
f factor in e. coli (f for fertility)
-
what does the f. factor in e. coli produce?
the ability to produce pilus
-
plasmids that give cells the ability to undergo conjugation and pass resistances to other cells are called what?
resistance factors
-
what happens when a phage infects a bacterial cell?
enzymes will cut up dna so when phage particles are being assembled pieces of bacterial dna may be packed in them
-
what is genetic engineering?
the process of inserting foreign genes into an organism (this is genetic recombination when it happens naturally)
-
dna with foreign material inserted in it
recombinant dna (rDNA)
-
an organism with recombinant dna can be called what?
recombinant, transgenic, or engineered organism
-
what is the outline for how bacteria are engineered?
- bacterial cells are processed and plasmids are collected
- seperately, cells with the gene you want to transfer are process and dna is collected
- plasmids and dna you want are cut open using enzymes and mixed together
- peices of dna with the gene you want will be inserted into some plasmids
- recombinant plasmids are inserted into new cells using transformation
-
what are vectors? what is the vector during genetic engineering?
transporters, plasmids
-
what enzymes cut open dna and plasmids during genetic engineering?
restriction enzymes
-
what is the most commonly engineered bacterium?
e. coli
-
what is the most commonly engineered eukaryotic organism?
saccharomyces cerevisiae (yeast)
-
when are viruses used as vectors?
used to engineer human cells for use in gene therapy
-
what are restriction enzymes?
bacterial enzymes that destroy phage dna
-
where do restriction enzymes cut the dna?
specific nucleotide sequences (produce sticky ends)
-
what are sticky ends? why are they called this?
short, single-stranded lengths; they tend to stick to complementary single strands
-
why are restriction enzymes useful?
pieces of dna cut with an enzyme can be inserted into the dna of another organism that's been cut with the same thing, they have the same sticky ends
-
what is complementary dna (cDNA)?
dna with the introns removed
-
what do introns prevent?
eukaryotic genes from being inserted into bacteria, because they cannot remove introns themself
-
dna with the introns removed can be produced using what?
transcriptase, enzyme produced by retroviruses
-
what is a summary of how cDNA works?
we use reverse transcriptase to produce cDNA and that allows us to engineer bacterial cells with eukaryotic genes
-
what is gene therapy?
genetic engineering of humans in order to treat disease
-
what kind of virus is usually used in gene therapy?
attenuated cirus
-
why are viruses used during gene therapy on humans?
they already have the ability to penetrate human cells and release dna
-
what attenuated virus is usually used in gene therapy?
adenoviruses (cause respiratory infections, like the common cold)
-
what has gene therapy successfully been used to treat?
SCID (severe combined immunodeficiency)
-
what do individuals that have been treated for SCID using gene therapy have a high risk of developing?
leukemia
-
what is PCR (polymerase chain reaction)?
process that makes multiple copies of a piece of dna (usually billions) within a couple of hours
-
the process of pcr runs in cycles of what?
heating and cooling of temps between 60-95 degrees Celsius, temperatures that would denature dna polymerase from mesophiles
-
pcr requires a heat stable dna polymerase, usually from what thermophilic bacterium?
thermus aquaticus
-
the is the dna polymerase from t. aquaticus usually referred to as?
taq polymerase
-
what methods are commonly used to insert recombinant dna into cells?
transformation, electroporation, microinjection, gene gun, viruses, and agrobacterium tumefaciens
-
what is electroporation?
a variation of transformation that uses an electric current to make the cell membrane leaky and allow dna to enter
-
what is microinjection?
dna can be injected directly into cells using an ultra-fine needle
-
what is microinjection useful for? why isn't it useful for bacterial cells?
animal cells and yeasts, it may be called microinjection but the needle is far too large for bacterial cells
-
how do you use a gene gun?
microscopic particles of gold are coated with dna and fire at cells
-
the gene gun is used for what cells?
eukaryotic
-
how does agrobacterium tumefacians work?
a plant pathogen that has the ability to inject dna into plant cells
-
agrobacterium tumefaciens is a plant pathogen that causes what?
gall
-
the ability to inject the dna and cause disease are carried on what plasmid?
ti-plasmid (tumor inducing)
-
where has agrobacterium tumefaciens been used?
used to engineer crops with various traits (ability to produce own pesticide), the crops produce protein crystals that harm digestive tracts of insects but are harmless to animals and human
-
what pesticide can plants produce on their own after being injected with agrobacterium tumefaciens?
bacillus thuringiensis
-
what are the crops genetically engineered called?
bt crops (bt corn, bt cotton, etc)
-
what can dna fingerprinting be used for?
to determine paternity, solve crime, trace outbreaks, and detect pathogens
-
what process is used to make a dna fingerprint?
cut up dna sample, copy it, seperate it, stain it, view it
-
for fingerprinting what is used to copy dna?
pcr makes multiple copies of fragments
-
how does seperating dna work with dna fingerprinting?
gel electrophoresis is used to seperate dna fragments according to length, electric current running through gel bath causes fragments to move through the gel, large fragments don't move far and small fragments do, this creates a fingerprint pattern
-
how do you stain dna in dna fingerprinting?
stained with ethidium bromide, dna gel is not visible so it must be stained to see, gel is soaked in a solution of ethidium bromide and the bromide wedges itself into the dna helix
-
how do you view dna during dna fingerprinting?
ethidium bromide is fluourescent, so when gel is exposed to uv light the band becomes visible
-
how can bacteria be identified using fingerprinting?
compare dna of a known species to the unknown species
-
how is the taxanomic hierarchy same/different with prokaryotes than eukaryotes?
it's the same except that prokaryotes are not assigned to kingdoms
-
what are subspecies of bacteria called?
stains or serotypes
-
what is a strain of e. coli?
e. coli 0157:H7
-
what bacterial family includes e. coli, salmonella, proteus, and other gram-negative intestinal bacteria?
enterobacteriaceae
-
what is the definitive guide to the identification and classification of bacteria?
bergey's manual
-
what three domains can all organisms on earth be divided into?
archaea, bacteria, and eukarya
-
bacteria domain is divided into more than how many phyla?
20
-
what are three of the well-known phyla of bacteria?
proteobacteria, firmicutes, and actinobacteria
-
what bacteria are usually in the phylum proteobacteria?
gram-negative
-
what are some well-known proteobacteria?
genera: escherichia, proteus, psuedomonas, neisseria, and salmonella
-
what does the phylum firmicutes include?
low GC gram-postive bacteria
-
what are the most well-known gram positive genera in firmicutes?
clostridium, bacillus, lactobacillus, staphylococcus, and streptococcus
-
what is GC content?
the percent of base pairs in an organisms dna are that are guanine-cytosine (GC is below 50%)
-
what does the phylum actinobacteria include?
high GC gram-positive bacteria
-
actinobacteria are often what?
filamentous
-
well known actinobacteria include what genera?
streptomyces and mycobacterium
-
more than how many species of fungi are known so far?
100,00
-
fungi are prokaryotic/eukaryotic
eukaryotic
-
fungi are aerobic/anaerobic
aerobic (molds/mushrooms), facultatively anaerobic (yeasts)
-
what metabolic group do fungi belong to?
chemoheterotrophs
-
how do fungi reproduce?
using spores (molds/mushrooms) or by budding (yeasts)
-
fungi are unicellular/multicellular
molds and mushrooms are multicellular and yeasts are unicellular
-
fungi contain what in their cell walls?
chitin
-
fungi contain what in their cell membranes?
sterols (ergosterol)
-
most fungi are...?
saprophytes (nutrients from dead and decaying material)
-
what is an example of a yeast?
saccharomyces cerevisiae (bread, beer, wine); candida albicans (yeast infections)
-
molds and mushroom structures are made up of what to make what?
multicellular hyphage to make a mycelium
-
where do you find spores on mold mycelium?
colored area in the center of a mold indicate spores
-
what is an example of a mold?
rhizopus stolonifer (black bread mold); penicillium (blue-green environmental mold)
-
do molds and mushrooms produce sexually/asexually?
both, either way they produce spores - if a spore lands in a suitable environment it germinates
-
molds and mushrooms don't have sexes they have...?
mating types - they produce asexually unti they meet an opposing mating type them produce sexually
-
when does sexual reproduction occur in molds and mushrooms?
opposite mating types fuse together (plasmogamy), their nuclei remaind seperate for a period of time, later when stimulted they nuclei fuse (karyogamy)
-
where does most of the mushroom growth reside?
below surface
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what is the part of the mushroom we see above ground? what is it's purpose?
a solid mass of hyphae produced during sexual reproduction; disperse spores
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what produces penicillin?
penicillium chrysogenum
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what can destructive fungi do?
cause disease, spoilage, and destruction
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what are fungal infections called? what is an example?
mycoses; yeast infectios caused by candida albicans
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what are fungal toxins called?
mycotoxins
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what percent of fungal species are harmful to humans?
less than 1%
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what percent of the worlds food crops are destroyed by fungi each year? what is an example?
one-fourth; rhizopus stolonifer, penicillium
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how can molds cause destruction?
mold growth in homes can require significant costs to replace damaged materials or remove toxins
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what is an example of a mold that can destroy a home?
stachybotrys chartarum, black mold that grows on wet building materials
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what can stachybotrys chartarum cause?
anything from headaches to organ damage
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are viruses alive?
no, no metabolism, reproduction, or cells
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what size are viruses?
smaller than bacteria, measured in nanometeres, require a microscope to see
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what do viruses contain?
nucleic acid (rna or dna) and a protein coat (capsid)
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viruses whose nucleic acid is single stranded
ssDNA
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viruses whose nucleic acid is double stranded
dsDNA
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what is the envelope of a virus made of?
cell membrane that the virus stole from the host cell when it escaped
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what can envelopes contain? what do they do?
spikes, attach to host cell
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the cells a virus can infect is determined by what?
specific receptors on the surface of cells
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a virus that infects a bacteria
bacteriophage
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viruses must be grown how? why?
by using a living host, they can't be grown in sterile media; they are obligate intracellular parasites
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how can bacteriophages be grown?
in culture media with their bacterial host
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how can many animal viruses be grown?
fertilized chicken eggs
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where are the viruses grown each year for use in influenze vaccines?
chicken eggs
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virus multiplication can be divided into what five major events?
attachment, penetration, biosynthesis, maturation, and release
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explain attachment of viruses
physical attachment to host cell exterior, virus binds to a specific receptor which is usually a polysaccharide or a protein
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explain penetration of viruses
movement of the virus from the exterior to the interior of the host cell
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how do non enveloped viruses enter cells?
endocytosis, host cell membrane invaginates and surrounds the virus and brings it in the cell in a vesicle
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how do enveloped viruses enter the cell?
endocytosis or fusion, the virus envelope melts into the host cell membrane
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how do plant viruses penetrate into plant cell walls?
plant cell walls are tough so it only happens when plant cells are damaged (by insects or gardening tools)
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how is bacteriophage penetration accomplished?
injecting the genetic material intot he cell wall while phage is outside the cell
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explain biosynthesis of viruses
production of virion parts, production of new dna or rna and new capsid proteins
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explain maturation of viruses
forms the whole mature virion
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explain the release of viruses
escape of virions from interior of cell to exterior, these infect new cells
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how are enveloped viruses released?
by budding (obtains its envelope from the cell membrane as it is exiting)
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how are non-enveloped viruses released?
when host cell becomes so full that it ruptures
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when viral dna inserts itself into the host chromosome the viral dna is called?
a provirus
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what are retroviruses?
rna viruses
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what is an example of a retrovirus?
HIV, causes AIDS
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how do proviruses work within a host cell?
they may never activate, but they are never removed and will call the viral dna as long as the cell is alive
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what are latent infections?
virus remains dormant in host cells for long periods of time without symptoms
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what is an example of a latent infection?
herpes viruses - remain latent inside nerves (cold sores, genital herpes, chicken pox)
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what are oncogenic viruses (oncoviruses)?
cancer causing viruses
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what is an example of an oncogenic virus?
human papillomavirus (HPV) causes cervical cancer; hepatitis B (HBV) causes liver cancer
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when do cancer causing viruses usually occur?
the insertion of a provirus disrupts an oncogene
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what is an oncogene?
a gene whose protein helps control cell division, cell can lose control over its cell division
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what percent is estimated of cancer is caused by viruses?
10% of all human cancers
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what are prions?
infectious proteins
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what do prions cause?
spongiform encephalopathies, or spongy brain diseases
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why are spongiform encephalopathies called spongy brain diseases?
infections results in death of brain cells, causes brain to form and fill with fluid and gives the brain a spongy appearance
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what an example of a prion?
scrapie, mad cow disease (bovine spongiform encephalopathy, BSE), Creutzfeldt-Jakob disese, kuru
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where does scrapie occur?
in sheep, this is where the first prion was discovered
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how could mad cow disease have been passed to cattle?
by feeding cattle contaminated sheep parts
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what is creutzfeldt-jakob disease?
most common human prion disease, CJD may have originally been transmitted through contaminated beef infected with neural tissue
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kuru affects who? how?
human in certain new guinea tribes whose burial practices involve eating parts of the deceased
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prions are mis-shapen verison of what?
normal brain proteins
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how does transmission of prions usually happen?
eating meats contaminated with brain or spinal cord tissue
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what are viroids?
infectious rna
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how do viroids probably work?
interfering with normal transcription/translation
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so far only what kind of viroids are known?
plant viroids
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what is an example of a plant viroid?
potato spindle tuber disease, which causes potatoes to grow into an enlongated shape
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