Qs from 6,7,8,9
assume you inoculated 100 facultatively anaerobic cells onto inoculated 100 cells of the same species onto nutrient agar and incubated the second plate anaerobically. after incubation for 24 hrs., you should have: a. more colonies on the aerobic plate b. more colonies on the anaerobic plate c. the same number of colonies on both plates
c. the same number of colonies on both plates
if u put a gene in a virus, the next step in genetic modification would be: a. insertion of a plasmid b. transformation c. transduction d. PCR e. southern blotting
c. transduction
mechanism by which the presence of glucose inhibits the lac operon:
catabolite repression
why can translation begin before transcription is complete in prokaryotes but not in eukaryotes?
cause in euk the mRNA needs to come out of the nucleus into the cytoplasm to start translation
What is the difference between complex and chemically defined media?
chemically defined: exact composition known
a population of cells carrying a desired plasmid:
clone
u have a smll gene u want replicated by PCR. u add radioactively labeled nucleotides to the PCR thermal cycler. after three replication cycles, what percentage of DNA single strands are radioactively labeled: a. 0% b. 12.5% c. 50% d. 87.5% e. 100%
d. 87.5%
two offspring cells are most likely to inherit from which parent cell: a. a chance in nucleotide in mRNA b. a change in a nucleotide in tRNA c. a change in a nucleotide in rRNA d. a change in a nucleotide in DNA e. a change in a protein
d. a change in a nucleotide in DNA
which cannot be used to sterilize a heat-labile solution stored in a plastic container: a. gamma radiation b. ethylene oxide c. supercritical fluids d. autoclaving e. short-wavelength radiation
d. autoclaving
which of the disinfectants does not act by disrupting the plasma memb.: a. phenolics b. phenol c. quaternary ammonium compound d. halogens e. biguanides
d. halogens
which of the following does not kill endospores: a. autoclaving b. incineration c. hot-air sterilization d. pasteurization e. all of the above kill endospores
d. pasteurization
the term "trace elements" refers to: a. elements CHNOPS b.vitamins c. nitrogen, phosphorus, sulfur d. small minerals requirements e. toxic substances
d. small minerals requirements
bacteria can acquire antibiotic resistance by all of the following except: a. mutation b. insertion of transposons c. conjugation d. snRNPs e. transformation
d. snRNPs
feedback inhibition differs from repression because feedback inhibition: a. is less precise b. is slower acting c. stops the action of preexisting enzymes d. stops the synthesis of new enzyme e. all of above
d. stops the synthesis of new enzyme
8.3d A mutagen that causes insertions
frameshift mutagen
the mechanism by which lactose controls the lac operon
induction
pieces of human DNA stored in yeast cells:
library
8.3e A mutagen that causes pyrimidine dimers
nonionizing radiation
8.3a A mutagen that is incorporated into DNA in place of a normal base
nucleoside analog
transfer of DNA from a donor to a recipient cell by a bacteriophage:
transduction
transfer of DNA frm a donor to a recipient as naked DNA in solution:
transformation
are bacteria capable of growing at a high osmotic pressure likely to be capable of growing in the mucus found in nostrils?
yes. S aureus can grow in the nasal passages. They have high tolerance to sodium chloride.
A pastry chef accidentally inoculated a cream pie with six S. Aureus cells. If S. Aureus has a generation time of 60 minutes, how many cells would be in the cream pie after 7 hours?
#cells x 2^n generations = total cells 6 x 2^7 = 768
does a base substitution always result in a diff. amino acid?
-no, it depends where the base substitution occurred. -if it occurs within a gene that codes for a protein (amino acid), the mRNA transcribed from the gene will carry an incorrect base at that position thus translating into an incorrect amino acid in the protein.
could you make a pour plate in the usual petri dish with a 10 ml inoculum? why?
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differentiate an RFLP from a gene.
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direct microscopic is used in estimating the bacterial population in dairy products. Why?
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do all mutagens cause cancer?
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do bacteria reproduce during conjugation?
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how dos reverse transcriptase differ from DNA polymerase?
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if the arithmetic numbers (solid line) were plotted for two more generations, would the line still be on the page?
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why can't the RNA transcript be used for translation?
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1. both selective and differential 2. selective
1. medium 1 is? 2. medium 2 is?
which bacterium would theoretically be more likely to grow at refrigerator temp.: a human intestinal pathogen or a soil borne plant pathogen?
Soil borne plant pathogen can grow in different type of temp. depending on environment so it would fine growing at refrigerator temp.
which of the following is more effective at sterilizing mattresses and plastic? a. chlorine b. ethelyne oxide c. glutaradehyde d. autoclaving e. non ionizing radiation
b
the DNA probe, 3' -GGCTTA, will hybridize with which: a. 5' -CCGUUA b. 5' -CCGAAT c. 5' -GGCTTA d. 3' -CCGAAT e. 3' -GGCAAU
b. 5' -CCGAAT
an that has peroxidase and superoxide dismutase but lacks catalase is most likely a: a. aerobe b. aerotolerant anaerobe c. obligate anaerobe
b. aerotolerant anaerobe
plasmids differ frm transposons in that plasmids: a. become inserted into chromosomes b. are self-replicated outside the chromosomes c. move from chromosomes to chromosomes d. carry genes for antibiotic resistance e none of above
b. are self-replicated outside the chromosomes
which is the fourth basic step to genetically modify a cell: a. transformation b. ligation c. plasmid cleavage d. restriction-enzyme digestion of gene e. isolation of gene
b. ligation
which of the temp. can kill a mesophile: a. -50 C b. 0 C c. 9 C d. 37 C e. 60 C
e. 60 C
8.3b A mutagen that causes formation of highly reactive ions
ionizing radiation
what is a vector in recombinant DNA technology?
plasmid
self-replicating DNA for transmitting a gene frm one organism to another:
vector
Pseudomonas has a plasmid containing the mer operon, which includes the gene for mercuric reductase. This enzyme catalyzes the reduction of the mercuric ions Hg2 to the uncharged form of mercury, Hg0. Hg2 is quite toxic to cells; Hg0 is not. --What do you suppose is the inducer for this operon? --The protein encoded by one of the mer genes binds Hg2 in the periplasm and brings it into the cell. Why would a cell bring in a toxin? --What is the value of the mer operon to Pseudomonas?
--The inducer for the operon is probably mercury ions. --The process of converting mercuric ion to mercury may have some benefits to Pseudomonas and that is probably why it brings it in. --This operon helps Pseudomonas survive in mercury rich environments.
What is an F+ cell?
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does RNAi act during or after transcription?
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does shotgun sequencing identify Genes and their locations?
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how could E. coli acquire the Shiga toxin gene?
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how do excision repair enzymes "know" which strand is incorrect?
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how is plastic filtration apparatus presterilized? (assume that plastic can't be heat sterilized)
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how might increased UV radiation affect the earth's ecosystems?
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how would an empty, uncapped flask be positioned for sterilization in an autoclave?
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if a single bacterium reproduced every 30 in, how many would there be in 2 hrs?
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if a technician were working with pathogenic prions, how would material leaving the lab be rendered noninfectious?
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in what instances would the pour plate method be more appropriate than the spread plate method?
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in what way is budding different from binary fission?
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is a colony formed as a result of streaking a plate always derived from a single bacterium? why or why not?
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name 4 other methods of inserting DNA into a cell.
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of what value are hemolysins to pathogens?
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under what circumstances is the MPN method used to determine the number of bacteria in a sample?
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what are some of the agricultural applications of recombinant DNA technology?
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what are some of the disadvantages of using a DNA synthesis machine?
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what causes transcription of a repressible enzyme?
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what causes transcription of an inducible enzyme?
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what is a DNA probe
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what is a gene? what is an open-reading frame?
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what is a mutagen?
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what is a protoplast?
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what is an auxotroph?
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what is forensic microbiology?
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what is one advantage of using E.coli for genetic engineering? one disadvantage?
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what is the advantage of semiconservative replication?
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what is the advantage of the degeneracy of the genetic code?
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what is the origin of replication?
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what is the purpose of southern blotting?
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what might bacteria provide for nanotechnology?
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what should have been used instead of aluminum foil to wrap the items for sterilization?
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what type of enzyme breaks the DNA?
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what type of enzyme cuts the donor DNA?
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when both glucose and lactose are present, why will cells use glucose first?
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when does transcription stop?
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when does translation stop?
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why are R factors important in the treatment of infectious diseases?
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why are transposons sometimes referred to as "jumping genes"?
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why are viruses with lipid-containing envelopes relatively susceptible to certain biocides?
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why is microinjection impractical for bacterial and fungal cells?
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why is the Ti plasmid important to biotechnology?
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why is the tincture of zephiran more effective than the aqueous solution?
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why is turbidity more useful in measuring contamination of liquids by large numbers, rather than small numbers, of bacteria?
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why were the dilutions of 1:10,000 and 1:100,000 not counted? theoretically, how many colonies should appear on the 1:100 plate?
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are quats most effective against gram-positive or gra-negative bacteria?
...gram-positive
1. a 2. b
1. which disinfectant is most effective? 2. which disinfectant(s) is/are bactericidal: a. all above b. a, c, and d c. a only d. B only e. none
1. c 2. a
1. which of the lines best depicts the log phase of a thermophile incubated at room temp? 2. which of the lines best depicts the log phase of Listeria monocytogenes growing in a human?
what is the term for bacteria that require a higher than atmospheric concentration of CO2 for growth?
Capnophiles
8.5 When iron is not available, E. Coli can stop synthesis of all proteins, such as superoxide dismutase and succinate dehydrogenase, that require iron. Describe a mechanism for this regulation
Iron deficiency could stimulate miRNA that is complementary to RNA encoding iron required proteins
which isn't a method of horizontal gene transfer: a. binary fission b. conjugation c. integration of a transposon d. transduction e. transformation
a. binary fission
which is used to control microbial growth in foods: a. organic acids b. alcohols c. aldehydes d. heavy metal e. all of the above
a. organic acids
a gene that hybridizes with mRNA
antisense
a classmate is trying to determine how a disingectant might kill cells. you observed that when he spilled the disinfectant in your reduced litimus milk, the litimus turned blue again. you suggest to the classmate: a. disinfectant might inhibit cell wall synthesis b. disinfectant might oxidize molecules c. disinfectant might inhibit protein synthesis d. disinfectant might denature proteins e. he take his work away from yours
b. disinfectant might oxidize molecules
which is most effective for sterilizing mattresses and plastic Petri dishes: a. chlorine b. ethylene oxide c. glutaraldehyde d. autoclaving e. nonionizing radiation
b. ethylene oxide
which is most likely to be bactericidal: a. membrane filtration b. ionizing radiation c. lyophilization (freeze drying) d. deep freezing e. all of the above
b. ionizing radiation
restriction enzymes were first discovered with the observation that: a. DNA is restricted to the nucleus b. phage DNA is destroyed in a host cell c. foreign DNA is kept out of a cell d. foreign DNA is restricted to the cytoplasm e. all of above
b. phage DNA is destroyed in a host cell
which type of media would not be used to culture aerobes: a. selective media b. reducing media c. enrichment media d. differential media e. complex media
b. reducing media
the following enzyme are used to make cDNA. what is the second enzyme used to make cDNA: a. reverse transcriptase b. ribozyme c. RNA polymerase d. DNA polymerase
b. ribozyme
which is not a characteristic of a quaternary ammonium compounds: a. bactericidal against gram-positive bacteria b. sporicidal c. amoebicidal d. fungicidal e. kills enveloped viruses
b. sporicidal
8.3c A mutagen that alters adenine so that is pairs with cytosine
base-pair mutagen
why is the prevention of biofilms important in a health care environment?
because biofilms are 1000 times more resistant to microbicides. -most nosocomial infections are prob. related to biofilms on medical catheters
why is osmotic pressure an important factor in microbial growth?
because it equalizes the pressure from its surrounding, thus helping preserve nutrients depending on the environment.
some iozenges intended to alleviate the symptoms of a sore throat contain phenol. why include this ingredient?
because phenol has significant antibacterial effect and local anesthetic effects
suppose you inoculate three flasks of minimal salts broth with E.coli. flask A contains glucose. flask B contains glucose and lactose. Flask C contains lactose. after a few hours of incubation, you test of the flasks for the presence of B-galactosidase. which flask will have the enzyme: a. A b. B c. C d. A and B e. B and C
c. C
which is not a characteristic of biofilms: a. antibiotic resistance b. hydrogel c. iron deficiency d. quorum sensing
c. iron deficiency