BIOL Last Module - HW review!
Which of the following statements about industrial products made by microbes is correct?
Regulatory mutants carry out production of amino acids such as lysine and glutamic acid that are used in the food industry as nutritional supplements.
Which of the following statements is false regarding the function of reverse transcriptase in the life cycle of HIV?
Reverse transcriptase acts as a DNA-dependent RNA polymerase when it transcribes dsDNA to mRNA.
T or F: The dilemma facing government agencies that regulate food is to find a balance between fresh, healthy, minimally-processed foods, and prevention of debilitating outbreaks of food-borne illness.
True
T or F: Viral lysozyme digests the host cell wall, releasing the newly made phage, and lysing the host cell in the release step.
True
The enzyme lysozyme is used by the T4 phages to enter the host cell.
True
What are the main modes of action in Antimicrobial drugs
stops cell wall synthesis protein synthesis inhibitors: drug binds to bacterial ribosome to target different protein synthesis steps metabolic antagonist : structural analogs block functioning of metabolic pathways Nucleic acid synthesis: inhibits DNA and RNA polymerase
Describe bacteriophage lambda's life cycle by completing each sentence: The start of its life cycle is similar to other bacteriophages, as it ___ to the host cell and ____ its genome.
attaches. inserts
Broad spectrum drugs
attack many different pathogens
Narrow spectrum drugs
attack only a few different pathogens
Opportunist pathogens
bacteria that induce disease under circumstances
mutualistic relationship
both organisms are benefitted and often cannot live without each other
Yet another use of heat is the sterilization of closed anaerobic containers in the _______ process
canning
Chemotherapeutic agents
chemicals used to treat disease by destroying bacteria or inhibiting their growth
Cytolytic Toxin
contains diphtheria exotoxin that interfere's with host cell protein synthesis, resulting in cell death
Great Plate count anomaly(GPCA)
count of number of cells seen under a microscope
Pathogen
disease producing organism
therapeutic dose
drug level required for clinical treatment
Toxic dose
drug level where drug becomes toxic
selective toxicity
drug selects to kill/inhibit pathogen while doing little damage to host
Describe bacteriophage lambda's life cycle by completing each sentence: If it does not enter the lytic cycle, its ________genome _____ into the host cell chromosome.
dsDNA. integrates
What are some primary metabolites
ethanol glutamate protease butanol
Primary metabolites made using industrial fermentation consist of compounds related to the synthesis of microbial cells during the _________ stage of growth.
exponential
Foods can be spoiled by both intrinsic and extrinsic factors. Extrinsic factors can include things such as _________
storage temperature
Toxin
substance that damages host
Neurotoxin
target nerve tissue
There are many different methods used to prevent food spoilage. Review common methods utilized to control food spoilage by completing each sentence. Another ancient method is the use of high ____ when cooking to kill many microbes present in food.
temperature
What are some Extrinsic characteristics
temperature humidity packaging
interspecies hydrogen transfer
the process where presence of a methanogenic archaeon consumes H2 produced as a fermentation product, shifting the change in free energy ( ΔG ) of the fermentation from positive to negative. It part of the mutualistic symbiosis between ruminant animals and their rumen microbial communities.
Therapeutic index
toxic dose to therapeutic dose ratio
Exotoxins
toxic substances that bacteria secrete into their environment
what are some secondary metabolites
toxins erythromycin bacitracin
Toxemia
toxins in the blood
Retroviruses have _________
two copies of single-stranded RNA
Many common methods of food preservation have been utilized since ancient times, such as salting, which lowers _______ ________ and inhibits microbial growth.
water activity
What are some Intrinsic characteristics
water activity presence of rind oxidation-reduction potential amount of carbohydrates
Syntrophic
when the growth of an organism depends on growth factors, nutrients or substrates provided by the other organism
If instead of being fatty, the foods are rich in proteins, anaerobic breakdown leads to
putrefaction
Foods richer in fats than grains can become_____, however, when fats are converted to short-chained fatty acids.
rancid
On the other hand, low temperatures used in __________ or freezing inhibit the growth of most microorganisms, but do not kill the microbes.
refiguration
Static agent
reversibly inhibits growth of microbes
Javier buys a package of fresh-sliced ham from the deli and places it in his refrigerator. Unbeknownst to him, there are 10,000 E. coli cells on his ham. After three days under refrigeration, predict the number of E. coli cells that would be on his ham, using what you know about the effects of refrigeration on most microbes.
slightly more than 10,000 cells
The correct order of the stages for phage replication are 1 = assembly 2 = attachment 3 = transcription/replication 4 = release 5 = penetration
2, 5, 3, 1, 4
Types of exotoxins
AB: a is the active part, and B is the binding part that binds exotoxin to receptor molecule on host
What products adsorb into environmental organic matter and are therefore subject to bioremediation?
All of the above
What are the two Hemolysins and their results
Beta-hemolysis: complete lysis, produces clear(yellow) around colony in blood agar Alpha-hemolysis: parital lysis, produces greenish zone around colony
Both Escherichia coli and Neisseria gonorrheae adhere to urethral epithelia using _________
Fimbriae
attributes that are necessary for any bacterial pathogen to attach to and colonize a host cell.
Capsule production Utilize spikes to attach to host cells Presence of fimbriae
If a toxin from Bacillus cereus is found in the stool samples of individuals who consumed contaminated rice, what symptoms would the individuals have suffered?
Cramps and diarrhea more than 24 hours after consumption
Which of the following statements is false regarding the control of microbial growth by altering the availability of water?
Foods with a high sugar content such as honey, jams and jellies, and syrup, have a high awaw value, which eliminates the growth of microbes.
What are the two membrane disrupting exotoxins
Pore-forming toxins: causes swelling, host cell lysis and death Phospholipase enzymes: subtype membrane distributing toxin that removes charged head group from host cell, causing cell lysis and death
Identify the stages of the T4 phage life cycle in the correct order.
DNA injection Early mRNA transduction Host DNA degreaded Phage DNA replicated Late mRNA transduction Production of phage tail and head Head is filled Virions form cell lysis
What are the ways to transport pathogen to host
Direct contact: cough, sneeze, body Indirect: water, food, fomites (inanimate objects; swings)
T or F: In the lysogenic stage of phage replication, the host cell is lysed.
False
T or F: Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again.
False
T or F: The Baltimore group termed retroviruses are the only viruses that use reverse transcriptase.
False
T or F: When food supplies, such as beef and pork, are gamma irradiated to kill pathogenic organisms, the food becomes temporarily radioactive. There is no harm to humans because the effects have worn off by the time the meat reaches grocery store shelves.
False (Gamma radiated food doesn't become radioactive)
T or F: Virulence is the potential for an organism to cause disease, whereas pathogenicity refers to the degree of harm caused by the organism.
False (Pathogenicity: ability to PRODUCE pathological change or disease) (Virulence: degree of harm inflicted on host)
T of F: The microbiota of chickens is a potential source of contamination during processing. To protect consumers, the FDA specifies the length of time allowed to cool the birds following slaughter; slower cooling times are preferred to preserve the flavor of the meat.
Fasle
How does bacteria typically leave the host?
Feces, urine, saliva
Which of the following utilizes reverse transcriptase to form DNA from a viral RNA template that is incorporated in the host DNA genome.
HIV
Food packaging can be extremely influential in how long it takes for a food to spoil. What type of food would take the longest to spoil?
Ham slices in modified atmosphere packaging
Evaluate the statements below and choose those that are correct regarding control of microbes by regulating the availability of water. High sugar content in food lowers the aw aw and dehydrates nonosmophilic microbes Jams, honey, and syrups will not spoil because of their high osmotic pressure Organisms in a hypotonic environment are dehydrated, which prevents food spoilage Osmophiles can withstand the effects of low awaw values and may still spoil foods like jams Nonosmophiles in a hypertonic environment are dehydrated, which limits food spoilage High salt increases the aw and causes dehydration in nonosmophilic microbes
High sugar content in food lowers the aw aw and dehydrates nonosmophilic microbes Osmophiles can withstand the effects of low awaw values and may still spoil foods like jams Nonosmophiles in a hypertonic environment are dehydrated, which limits food spoilage
The three characteristics of pathogen virulence
Invasiveness, infectivity, and pathogenic potential
How does high-oxygen modified atmosphere packaging preserve food?
It stimulates the formation of radical oxygen species in contaminating microorganisms
Bacteriophage lambda can enter either the lytic cycle or the _____ cycle and therefore is considered a ______ phage.
Lysogenic. phage
What is the mechanism of Drug resistance?
Modify target of antibiotic Drug inactivation minimize concentration of antibiotic in cell bypass biochemical reaction stopped by the agent or increase production of target metabolite
When stored under moist conditions, grains can support the growth of
Molds
Single-stranded RNA viruses containing RNA sequences that are complementary to the mRNA produced upon their infection of a host cell are called _________blank RNA viruses.
Negative stranded
Two examples of Commensalism
Nitrification: nitrobacter benefits working with Nitrosomonas and they work together nonpathogenic E.coli in human colon: E.coli consumes oxygen, creating an environment for bacteroides
Parasitism
One organism benefits and the other is harmed (has to co-exist though)
Adherence structures
Pili and fimbriae
Three Mutualist examples
Tube warm and bacteria. Bacteria lives in the trophosome of the host tube warm, to aid in worm growth Rumen ecosystem: ruminants contain rumen part of their stomach that contains a microbial community that helps the animal use CO2 and H2 to generate methane Insects: Insect provides habitat while bacteria provides amino acids
What can cause a phage in the lysogenic stage to revert to the lytic stage?
Ultraviolet light
Toxicity
ability for organism to cause disease by a toxin that stops host cells function or kills the host cells
Pathogenicity
ability to cause disease
What are the ways pathogen can invade?
active penetration : bacteria enters through cell wall Passive penetration: insect bites, wounds
Describe bacteriophage lambda's life cycle by completing each sentence: Stress can activate the process of ______ where the integrated phage genome is excised.
induction
Expalin dilution susceptibility tests
inoculating media containing different concentrations of the drug
Describe bacteriophage lambda's life cycle by completing each sentence: This process is catalyzed by the enzyme ____ at an attachment site and the genome remains in the chromosome as a ______
intagrace. Prophage
Endotoxins
is bound to the bacterium and is released when organism lyses and during multiplication
Why is human intestinal flora important?
it carries out a variety of essential metabolic reactions resulting in a variety of products (like Vit B12 and K)
Cidal Agent
kills target pathogen
Minimal lethal concentration (MLC)
lowest concentration of drug that kills bacteria
Minimal inhibitory concentrations(MIC)
lowest concentration of drug that prevent bacterial growth
Describe bacteriophage lambda's life cycle by completing each sentence: The excised genome becomes active and progression into the _______ cycle eventually leads to death of the host cell.
lytic
Low temperature holding (LTH) pasteurization, commonly used to treat milk, beer, and fruit juices, heats the liquid for _________
minutes
Recent metagenomic investigations reveal that human microbiome is extremely diverse and both human and microbes benefit. The relationship is best described as _________
mutualistic
The ID50 refers to the _________
number of organisms in the initial inoculum required to cause infection in 50% of hosts
One type of bioremediation process promotes the growth of natural microbial populations that can degrade a given contaminant by adding _________to the contaminated site.
nutrients
Commensalism
one organism benefits and the other is unaffected
Amensalism
one organism causes negative impact on the other organism based on a release of a compound
In phage replication step _________
only the phage nucleic acid enters the bacterial cell
There are many different methods used to prevent food spoilage. Review common methods utilized to control food spoilage by completing each sentence. This process was advanced in the case of milk _____, where slightly lower temperatures are applied yet still effective in killing potential pathogens.
pasteurization
Microbial predators
predatory bacteria that attacks and kills its prey
ex of amensalism
production of antibacterial peptides by insects and animals
In the attachment step of phage replication _________
protein fibers in the phage tail attach to specific receptors on the bacterial cell wall