Exam 2 (Chapters 7, 11, 12, 13) Flashcards
Term that refers to bacterial contamination:
sepsis
Term that refers to the absence of significant contamination:
asepsis
Term for removing and destroying all microbial life:
sterilization
What is an example of commercial sterilization?
killing C. botulinum endospores from canned goods.
This is used to destroy harmful microorganisms from fomites:
disinfection
Term for destroying harmful microorganisms from living tissue:
antisepsis
What is degerming?
mechanical removal (rather than killing) of microbes from a limited area (ex: handwashing).
This is used to lower microbial counts on eating utensils to safe levels:
sanitization
Treatments that kill microbes:
biocide (germicide)
Inhibiting, but not killing microbes:
bacteriostasis
What are some factors that affect the rate of microbial death?
number of microbes, environment, time of exposure, microbial characteristics
How does the environment affect the rate of microbial death?
Things to consider: if there is a nutrient source for the microbe (organic matter), temperature, and if biofilms are present and adhere to a substrate making them harder to kill.
What kind of microbial characteristics would effect the rate of microbial death?
cell wall components: is it gram negative? does it have mycolic acid? what are its metabolic pathways?
What are the three targets of chemical reagents on cell (antimicrobials)?
alteration of membrane permeability, damage to proteins (enzymes), damage to nucleic acids
What does the alteration of membrane permeability do to a cell?
if the lipids and proteins of the membrane are damaged, the cell contents can leak out which leads to cell death.
What does damage to proteins do to a cell?
Breaks the bonds that keep the enzymes in their three dimensional shape
What does damage to nucleic acids do to a cell?
disrupts replication and normal metabolic function (DNA makes proteins/enzymes)
What are the physical methods of microbial control?
heat (wet heat or dry heat), pasteurization (moist heat), filtration, radiation
What is one of the main benefits of using heat from microbial control?
heat denatures enzymes/proteins which destroys the 3D shape so that proteins can’t do their job
Term for the lowest temperature at which all cells in a liquid culture are killed at 10 minutes:
Thermal death point (TDP)
Term for the minimal time for all bacteria in a liquid culture to be killed at a particular temperature:
Thermal death time (TDT)
Which guidelines indicate the severity of treatment required to kill a given population of bacteria?
Thermal death point (TDP) and Thermal death time (TDT)
What is Decimal reduction time (DRT)?
minutes to kill 90% of a population at a given temperature
What does moist heat sterilization do?
denatures proteins and coagulates them like an egg white being fried
What type of moist heat sterilization kill vegetative (non-spore forming) bacteria, almost all viruses, and fungi and their spores within about ten minutes?
boiling
Is boiling good for killing endospores?
No. Endospores help the virus or bacteria resist a hostile environment
Term for “steam under pressure”
autoclave
What form of sterilization kill as organisms and endospores, but the steam must contact the item’s surface to do so:
autoclave: 121 degree C at 15 psi or 15 minutes
When an organism survives pasteurization and is heat resistant:
thermoduric
What type of moist heat reduces spoilage organisms and pathogens–also reduces microbial numbers to prolong good food quality during refrigeration?
pasteurization
At what temperature does pasteurization denature bacterial proteins?
63 degrees C for 30 minutes
What process kill microbes by oxidation?
dry heat sterilization (flaming, incineration)
Why would hot air sterilization be used?
glassware
Why is filtration used?
for heat-sensitive materials
Term for freeze drying:
lyophilization
Term for the absence of water preventing microbe metabolism:
desiccation (bacteriostatic method)
What kind of method uses salts and sugars to create hypertonic environment; causes plasmolysis–used in food preservation:
osmotic pressure (high solute concentration pulls water out of cell)
Name three types of radiation:
ionizing radiation, nonionizing radiation, microwaves
How does ionizing radiation work?
ionizes water to create reactive hydroxyl radicals; damages DNA by causing lethal mutations which can cause a cell to die.
How does nonionizing radiation work?
does NOT cause water to split into ions; damages DNA by creating thymine dimers (how melanoma forms)
How do microwaves control microbial growth?
kill by heat, but they are not especially antimicrobial
How does the disk-diffusion method work for evaluating a disinfectant?
Filter paper disks are soaked in a chemical and placed on a culture; look for ZONE OF INHIBITION around disks which shows if a bacteria is more susceptible or more resistant to a particular disinfectant
What method evaluates the efficacy of chemical agents?
disk-diffusion method
How many phyla does the domain bacteria have?
14
List the gram-negative phyla:
proteobacteria, cyanobacteria, chlamydiae, bacteriodetes, fusobacteria, spirochaetes, deinococcus
List the gram-positive phyla:
firmicutes, actinobacteria
What is the largest phyla of bacteria?
Phylum Proteobacteria
What are general characteristics of Proteobacteria?
gram-negative, chemoheterotrophic, largest taxonomic group of bacteria
Characteristics of Alpha-proteobacteria:
grow with low levels of nutrients, agriculturally important, capable of nitrogen fixation (symbiotic relationship with plant roots)
Genus in Alpha-proteobacteria:
Rickettsia, Bartonella
Characteristics of the Genus Rickettsia:
obligate intracellular parasite, cause spotted fevers, vector transmission (insect, tick)
Characteristics of the Genus Bartonella:
human pathogen, cat-scratch disease
Genus in Betaproteobacteria:
Bordatella, Neisseria
Characteristics of Bordatella and a pathogen:
non-motile, aerobic, gram-negative rods; B. pertussis
Characteristics of Neisseria and pathogens:
aerobic, gram-negative cocci; inhabits mucous membranes of mammals; N. gonorrhoeae, N. meningitidis
What toxin do Phylum Cyanobacteria produce?
neurotoxin
Characteristics of Phylum Cyanobacteria:
carry out oxygenic photosynthesis, nitrogen fixation, thought to play important role in increasing O2 concentration in the atmosphere
What phylum causes the most common STD in the U.S.?
Phylum Chlamydiae
Characteristics of phylum Chlamydiae:
obligate intracellular parasite (must have host cell), does not have peptidoglycan cell wall
What causes trachoma (blindness in 3rd world countries)?
Chlamydia trachomatis
Characteristics of Phylum Spirochaetes?
Gram negative, move via axial filaments (like a corkscrew)
What pathogen causes syphilis?
Treponema pallidum
What pathogen causes Lyme disease?
Borrelia
What Phylum has more durable cells that are resistant to radiation and high temperatures?
Phylum Deinococci
Name two unusual bacteria in Phylum Deinococci:
Deinococcus radiodurans, Thermus aquaticus
Characteristics of Deinococcus radiodurans:
even more resistant to radiation than endospores, can survive radiation exposure 1500 times greater than a human
Characteristics of Thermus aquaticus:
found in a hot spring in Yellowstone, source of Taq polymerase which is an enzyme used in PCR to amplify DNA.
What bacteria produces Taq polymerase which is used in PCR to amplify DNA?
Thermus aquaticus
Name the two phyla that are gram-positive:
Firmicutes, Actinobacteria
Characteristics of Actinobacteria:
pleomorphic; branching filaments; common inhabitants of soil
What phylum is a common inhabitant of soil?
Actinobacteria
About how many bacterial species have been described?
5000
Are most fungi pathogenic?
no. There are greater than 100,000 species and only about 200 are pathogenic
What is mycelium?
mass of hyphae
What are two types of fungal reproduction?
asexual and sexual
What are the two growth patterns of fungi?
unicellular yeasts; multicellular molds and mushrooms
What is the term for a fungal infection?
mycosis
What domain and kingdom are fungi in?
Domain: Eukarya; Kingdom: Fungi
Name four Phyla of medically important fungi:
zygomycota, microsporidia, ascomycota, basidiomycota
Name the five types of mycoses:
systemic mycoses, subcutaneous mycoses, cutaneous mycoses, superficial mycoses, opportunistic mycoses
What are some of the economic impacts of fungi?
Saccharomyces cerevisiae (bread, wine, hep B vaccine), Taxomyces (taxol: cancer treatment)
Do algae cause infectious diseases?
Algae are not pathogenic but some produce toxins which could affect humans and produce neurological problems.
Name the three medically important classes of Protozoa:
Sarcomastigophora, Ciliophora, Apicomplexa
What class of protozoa includes amoeba and flagellated protozoans?
Class Sarcomastigophora
Give examples of Class Sarcomastigophora:
Trypanosoma, Trichomonas, Leishmania
Give an example of a pathogen in Class Ciliophora:
Balantdidium coli (causes colitis and is the only parasitic ciliate of humans)
Give an example of Class Apicomplexa:
Plasmodium species, Toxoplasma gondi
What kingdom do helminths belong to?
Animalia
What are the two phyla of helminths that are parasitic?
Platyhelminthes (flatworms), Nematoda (roundworms)
What phyla contains flatworms?
Platyhelminthes
What phyla contains roundworms?
Nematoda
Term for the primary host who harbors the sexually reproducing parasite:
definitive host
Term for the secondary host that harbors the larval stage of a parasite:
intermediate host
How do arthropods act as vectors in causing disease?
They transmit disease on their feet or in their body without being infected themselves (mechanical vector); or when an infected arthropod transmits a pathogen by a bite or other wound (biological vector)
Term for arthropods that carry pathogenic microorganisms:
vector
Microbes will ___ at a ____ _____ when heated or treated with antimicrobial chemicals.
die; constant rate
Term for a microbe that requires a living host cell to multiply:
obligate intracellular parasite
What are the minimum components of a virus?
nucleic acid, protein coat
What does a virus use a host for?
enzymes for protein synthesis and generating ATP
How is “host range” determined?
most viruses infect only specific types of cells in one host. This is determined by specific host attachment sites.
What is a complete, fully developed viral particle?
virion
What does every virus have?
nucleic acid and capsid (protein coat)
Name the four possible components of a virus:
nucleic acid, capsid, envelope, spikes
If a virus has an envelope, what is it made of?
lipid, protein, and carbohydrate coating made from cell components
This structure is host derived and resembles a plasma membrane:
envelope
What is the general morphology of naked viruses?
helical (rabies, ebola) and polyhedral (adenovirus, poliovirus)
Name some enveloped viruses that are human pathogens:
Herpes, mumps, measles, rubella, hep B, Corona, rabies, influenza, poxviruses, HIV
What type of virus (naked or enveloped) is easier to destroy with chemical agents?
enveloped viruses
What type of virus (naked or enveloped) is harder for our immune system to destroy?
enveloped viruses
What part of a virus is more resistant to chemical agents?
capsid
Name some naked viral human pathogens:
HPV, rotavirus, norovirus, poliovirus, rhinovirus
What informs to the severity of treatment required to kill a given population of bacteria?
Thermal death point and thermal death time
Term for an exponential decline in a population of bacteria:
Decimal reduction time (DRT)
Term for tumor viruses; becomes integrated into the host cell’s DNA and induces tumors:
oncogenic virus
Give examples of DNA Oncogenic Viruses:
adenoviridae, herpesviridae, poxviridae, papovaviridae (HPV), hepadnaviridae (hep B)
Give examples of RNA Oncogenic Viruses:
Retroviridae (COVID, HIV)
What are two enzymes RNA viruses need for replication?
reverse transcriptase
What are prions?
proteinaceous infectious particles (protein that is infectious)
What class of disease do prions cause?
spongiform enchephalopathies
What is an example of a spongiform encephalopathy?
Creutzfeldt-Jakob disease, mad cow disease
What is used to indicate sterility after autoclaving?
test strips
Do large containers require longer sterilization times in the autoclave?
yes
Term for microbes that survive pasteurization:
thermoduric
Low temperature has _____ effect.
bacteriostatic (refrigeration, deep-freezing, freeze drying)
lyophilization is:
freeze drying
Primary decomposer of plant matter:
fungi
What helps plants roots absorb minerals and water from the soil–symbiotic relationship between plants and fungi
mycorrhizae
What is the main component of the cell wall in fungi?
chitin (mushrooms), glucan and mannans in yeast
Fungal colonies are described as _____ structures because they contain cells involved in catabolism and growth.
vegetative
The fungal body is called:
thallus
How does yeast reproduce?
budding (divide unevenly)–alcohol fermentation, fission (divide evenly)
This term for fungi means that it can exhibit two forms of growth which is common in pathogenic fungi. It can be yeastlike at 37 degree C and moldlike at 25 degree C.
dimorphic fungi
Example of dimorphic fungi that infects humans:
histoplasmosis
Reproductive structure of fungi:
spores (asexual and sexual reproduction)
Are endospores reproductive?
No. Only fungal spores are reproductive
How are asexual spores produced?
mitosis and cell division (produces genetically identical organism)
What are two fungi that reproduce asexually?
conidiospore, sporangiospore
How do fungi reproduce sexually?
Not male and female, they have opposite mating strains that undergo a fusion of nuclei
Almost all molds are ____.
aerobic
Most yeasts are _____ anaerobes.
facultative (without oxygen undergo fermentation)
How are fungi more adapted to environments that are hostile to bacteria?
Grow in high sugar and salt concentration; resistant to osmotic pressure; can grow in low moisture content; low nitrogen environment; can metabolize complex carbohydrates
Algae are _____ or _____ photoautotrophs.
unicellular; filamentous
Are protozoa unicellular?
Yes. Unicellular eukaryotes
What is the feeding and growing form of a protozoa?
trophozoite
How do protozoans reproduce?
asexual reproduction by fission, budding, schizogony; sexual reproduction by conjugation
Can viruses be seen with light microscopes?
No they are too small
Do viruses have a cellular structure?
No, they do not have cell structure
What is the ecological niche of a virus?
It’s host range: HIV infects Helper T cells; HPV infects epithelial cells
Viruses that are not pathogenic to humans and only infect bacteria:
bacteriophages
What device is required to visual viruses?
electron microscope
Viral particle capable of infecting a host cell:
virion
What type of nucleic acids can viruses have?
DNA or RNA can be single or double stranded; linear or circular
Regardless of the shape of the capsid, enveloped viruses will always look:
spherical
Is ebola naked or enveloped?
naked
Term for a group of viruses sharing the same genetic information and ecological niche (host range):
viral species
Viruses must be grown in _____ cells in the lab.
living
What do you look for when growing viruses in the lab?
plaques which are clearings of bacteria and represent viral particles
What genus is an obligate intracellular parasite, gram negative, causes spotted fevers, and is transmitted by insect or tick bites?
Rickettsia
What genus is a human pathogen that is a gram-negative bacteria causing cat-scratch disease?
Bartonella
Name two pathogens that are Beta-proteobacteria:
Bordatella and Neisseria
What Genus causes whooping cough?
Bordatella
What Genus includes gram-negative cocci that inhabit mucous membranes of mammals; causes gonorrhea and meningococcal meningitis
Neisseria
What Class contains Pseudomonadales and Vibrionales?
Gammaproteobacteria
Enterobacteriales inhabit the ______.
intestinal tract
The Order Enterobacteriales includes:
Escherichia, Salmonella, Serratia, Yersinia, Pasteurellales
Epsilonproteobacteria include:
campylobacter and helicobacter
What phylum contains the oxygenic photosynthetic bacteria?
Cyanobacteria
What phylum contains the most common STD in the US?
Chlamydiae
What is a plant pathogen made of short pieces of make RNA with no protein coat?
Viroid
