MCB 2010: Ch 8

C) provide an environment in which preexisting mutants survive.

Antibiotics A) cause mutations to occur. B) may act as alkylating mutagens. C) provide an environment in which preexisting mutants survive. D) increase the rate of spontaneous mutation. E) destroy all mutant bacteria.

D) genetic recombination.

Bacteria that have properties of both the donor and recipient cells are the result of A) UV light. B) SOS repair. C) frame shift mutations. D) genetic recombination. E) antibiotic resistance.

E) histidineAND streptomycin

Cells that are His -, Str R could be isolated from a mixed sample by using a medium containing A) streptomycin B) histidine AND glucose C) penicillin AND streptomycin D) glucose AND streptomycin E) histidineAND streptomycin

D) hydrogen bondingproperties of the nucleobase.

Chemical mutagens often act by altering the A) alkyl groups of thenucleobase. B) nucleobasesequence. C) number of bindingsites on the nucleobase. D) hydrogen bondingproperties of the nucleobase. E) nucleobases.

C) base analogs.

Chemical mutagens that mimic the naturally occurring bases are called A) nitrogen mustards. B) alkylating agents. C) base analogs. D) nitrous oxide. E) nucleobase copiers.

C) phenotypic change.

Colonies of the bacterium Serratia marcescens are red when incubated at 22°C but white when incubated at 37°C. This is an example of A) antigenic variation. B) genotypic change. C) phenotypic change. D) mutation. E) selective media.

B) are mutagens.

The Ames test is useful as a rapid screening test to identify those compounds that A) will respond to chemical agents. B) are mutagens. C) respond to the deletion of DNAses. D) will protect an organism from cancer. E) will respond to chemical agents AND will protect an organism from cancer.

A) the sex pilus.

The F plasmid carries the information for A) the sex pilus. B) recipient cell DNA replication. C) antibiotic resistance. D) the Y chromosome. E) bacterial flagella.

B) Agrobacterium.

The Ti plasmid is naturally found in A) Escherichia. B) Agrobacterium. C) Pseudomonas. D) Staphylococcus. E) E. coli AND Staphylococcus.

C) plant cells.

The Ti plasmid is used as a vector to transfer DNA into A) viruses. B) bacteria. C) plant cells. D) animal cells. E) protozoa.

C) UV radiation.

The formation of a covalent bond between two adjacent thymines is caused by A) X-rays. B) alkylating agents. C) UV radiation. D) microwave radiation. E) heat.

B) alkylating agents.

The largest group of chemical mutagens consists of A) radiation. B) alkylating agents. C) nitrous acid. D) base analogs. E) intercalating agents.

B) Avery, MacLeod, and McCarty.

The material responsible for transformation was shown to be DNA by A) Watson and Crick. B) Avery, MacLeod, and McCarty. C) Lederberg. D) Stanley. E) Beadle and Tatum.

B) transduction.

The mechanism by which genes are transferred into bacteria via viruses is called A) ellipsis. B) transduction. C) replica plating. D) transformation. E) conjugation.

A) phenotype.

The properties of a cell that are determined by its DNA composition are its A) phenotype. B) genotype. C) metabolism. D) nucleoid. E) plasmids.

C) penicillin enrichment.

To increase the proportion of auxotrophic mutants in a population of bacteria, one may use A) direct selection. B) replica plating. C) penicillin enrichment. D) individual transfer. E) mutant reversion.

A) Core genome; accessory genome; unique genes

What comprises the pan-genome of a given species? A) Core genome; accessory genome; unique genes B) Core genome; accessory genome C) Core genome; unique genes D) Core genome; accessory genome; unique genes; genomic islands E) Core genome; accessory genome; unique genes; pathogenicity islands

D) They were first recognized in fungi.

Which of the following about transposons is not true? A) They are informally known as jumping genes. B) They may cause insertion mutations. C) They may cause knockout mutations. D) They were first recognized in fungi. E) All of the statements are true.

A) Transcription

Which of the following does not introduce DNA into a bacterial cell? A) Transcription B) Conjugation C) Transduction D) Transformation E) All of these introduce DNA into a cell.

C) Agrobacterium

Which of the following genera has proved useful for manipulating plant cells? A) Escherichia B) Bacillus C) Agrobacterium D) Pseudomonas E) Rhizobium

B) The bacterial host DNA is protected from restriction enzymedegradationby phosphorylation.

A bacterial strain is resistant to infection by abacteriophage. Which statement is FALSE? A) The bacteria make restriction enzymes that degrade the virus genome. B) The bacterial host DNA is protected from restriction enzymedegradationby phosphorylation. C) The bacterial host DNA is protected from restriction enzyme degradationby methylation. D) If the phage DNA was methylated, it would be protected from restriction enzyme degradation. E) The statements are ALL false.

B) replica plating.

A clever technique that streamlines the identification of auxotrophic mutants is A) gas chromatography. B) replica plating. C) direct selection. D) reversion. E) intercalation.

B) thymine dimers.

Irradiation of cells with ultraviolet light may cause A) four nucleotides to covalently bind together. B) thymine dimers. C) adenine complementary base pairing with cytosine. D) the addition of uracil. E) cytosine trimers.

E) Yes—the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, these would lead to higher rates of successful transduction.

A mutation in E. coli results in the loss of both restriction endonucleases and modification enzymes. Would you expect any difference in the frequency of gene transfer via transduction FROM Salmonella INTO this E. coli strain? A) No—since the Salmonella strain is normal, the rate of production of transducing virus particles would still be the same, resulting in the same frequency of gene transfer. B) Yes—the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading"' viral DNA from the transducing phage. This would lead to higher rates of successful transduction. C) Yes—the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. This would lead to higher rates of successful transduction. D) No—transduction efficiency isn't affected by either restriction endonucleases or modification enzymes, so there'd be no effect on the overall rate. E) Yes—the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, these would lead to higher rates of successful transduction.

A) spontaneous mutation.

A patient comes to see you complaining of a spider bite. He shows you a sore on his wrist—the area around it is red and swollen, and the lesion is leaking pus. The patient tells you he found a spider in his car, which is why he thinks this is a bite. He also tells you that he has been taking penicillin tablets that his wife had left over after being prescribed the drug a few months previously for pneumonia. Even though he has taken the tablets for four days,the lesion is not healing and that he is really feeling terrible, with pain, fever, and chills. You suspect that your patient has a wound infection, so you sample the pus and send it to the lab for analysis. Further tests indicate that your patient has a methicillin-resistant Staphylococcus aureus (MRSA) infection. You explain to the patient that these bacteria are not impacted by penicillin or the related drug methicillin. This resistance is thought to have arisen originally by a random change in the cell's chromosome through a process called A) spontaneous mutation. B) antigenic variation. C) quorum sensing. D) vertical gene transfer. E) indirect selection.

C) Staphylococcus; Gram-positive

A patient comes to see you complaining of a spider bite. He shows you a sore on his wrist—the area around it is red and swollen, and the lesion is leaking pus. The patient tells you he found a spider in his car, which is why he thinks this is a bite. He also tells you that he has been taking penicillin tablets that his wife had left over after being prescribed the drug a few months previously for pneumonia. Even though he has taken the tablets for four days,the lesion is not healing and that he is really feeling terrible, with pain, fever, and chills. You suspect that your patient has a wound infection, so you sample the pus and send it to the lab for analysis. The lab results indicate that the pus from your patient's "bite" contains clusters of spherical cells that stained purple in the Gram stain. You tell your patient that his wound contains bacteria from the genus______ and is classified as a ______ organism. A) Escherichia; Gram-negative B) Streptococcus; Gram-positive C) Staphylococcus; Gram-positive D) Streptobacillus; Gram-positive E) Vibrio; Gram-negative

D) transposon

A patient comes to see you complaining of a spider bite. He shows you a sore on his wrist—the area around it is red and swollen, and the lesion is leaking pus. The patient tells you he found a spider in his car, which is why he thinks this is a bite. He also tells you that he has been taking penicillin tablets that his wife had left over after being prescribed the drug a few months previously for pneumonia. Even though he has taken the tablets for four days,the lesion is not healing and that he is really feeling terrible, with pain, fever, and chills. You suspect that your patient has a wound infection, so you sample the pus and send it to the lab for analysis. You explain to your patient that there has been an increase in the number of strains of S. aureusthat are now resistant to methicillin. The gene conferring resistance has moved from one strain to another via mobile gene elements, an example of which is a(n) ______. A) bacteriovirus B) insertional divider C) histone D) transposon E) chromosome

D) inhibiting protein synthesis.

A patient comes to see you complaining of a spider bite. He shows you a sore on his wrist—the area around it is red and swollen, and the lesion is leaking pus. The patient tells you he found a spider in his car, which is why he thinks this is a bite. He also tells you that he has been taking penicillin tablets that his wife had left over after being prescribed the drug a few months previously for pneumonia. Even though he has taken the tablets for four days,the lesion is not healing and that he is really feeling terrible, with pain, fever, and chills. You suspect that your patient has a wound infection, so you sample the pus and send it to the lab for analysis. Your patient asks whether there is any way for him to get rid of this infection. You tell him that he will be given a different antibiotic such as doxycycline. This antibiotic works by binding to a cell structure called the 30S ribosomal subunit, which stops the bacterial cells from growing by A) preventing DNA replication. B) inhibiting transcription. C) stopping capsule formation. D) inhibiting protein synthesis. E) preventing protein packaging.

B) The bacteria causing the infection are resistant to penicillin; a different antibiotic is needed.

A patient comes to see you complaining of a spider bite. He shows you a sore on his wrist—the area around it is red and swollen, and the lesion is leaking pus. The patient tells you he found a spider in his car, which is why he thinks this is a bite. He also tells you that he has been taking penicillin tablets that his wife had left over after being prescribed the drug a few months previously for pneumonia. Even though he has taken the tablets for four days,the lesion is not healing and that he is really feeling terrible, with pain, fever, and chills. You suspect that your patient has a wound infection, so you sample the pus and send it to the lab for analysis. Your patient asks why the penicillin he has been taking hasn't helped his infection. Which of the following is a possible explanation for your patient? A) The patient has become resistant to penicillin and he needs to take a different medication. B) The bacteria causing the infection are resistant to penicillin; a different antibiotic is needed. C) Bacteria are never killed by a single type of antibiotic; combinations of drugs are needed. D) Penicillin has been overused by people and it no longer works against any bacteria; it can be used against viruses. E) The patient's body is neutralizing the antibiotic; he needs to take a probiotic to help the penicillin work.

C) Ames.

A quick microbiological test for potential carcinogens was developed by A) Fleming. B) Lederberg. C) Ames. D) Crick. E) McClintock.

D) involve haploid chromosomes AND involve antibiotic resistance.

Among the easiest of the mutations to isolate are those which A) involve polyploid chromosomes ANDallow populations to be measured. B) involve antibiotic resistance AND allow populations to be measured. C) allow populations to be measured AND use an indirect method for measurement. D) involve haploid chromosomes AND involve antibiotic resistance. E) use an indirect method for measurement AND involve antibiotic resistance.

B) are able to take up naked DNA, occur naturally, AND can be created in the laboratory.

Competent cells A) are able to take up naked DNA, can be created in the laboratory,AND are alwaysantibiotic resistant. B) are able to take up naked DNA, occur naturally, AND can be created in the laboratory. C) are always antibiotic resistant, are always auxotrophs,AND occur naturally. D) can be made in the laboratory, are alwaysantibiotic resistant, AND are always auxotrophs. E) are able to take up naked DNA,occur naturally, AND are always antibiotic resistant.

true

Crown gall is caused by a prokaryote plasmid that can be expressed in plant cells. ⊚ true ⊚ false

C) methylated.

DNA is protected from restriction enzymes by being A) sequestered in a lysosome. B) turned into RNA. C) methylated. D) made into double-stranded RNA. E) phosphorylated.

true

DNA polymerase is able to proofread the DNA sequence. ⊚ true ⊚ false

C) in both eukaryotes and prokaryotes.

DNA repair mechanisms occur A) only in prokaryotes. B) only in eukaryotes. C) in both eukaryotes and prokaryotes. D) in neither eukaryotes nor prokaryotes. E) None of the answer choices is correct.

C) Directcell-to-cell contact is required for this process, and this is more likely tobe achieved in the fluid liquid format than on an agar plate (especially forrelatively non-motile types of bacteria).

DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why? A) Directcell-to-cell contact is required for this process, and this is more likely tobe achieved in the plate format than in the fluid format (especially forrelatively non-motile types of bacteria). B) Directcell-to-cell contact isn't required for this process, so the ability to secretethe DNA into the surrounding fluid medium makes the process more efficient thanthe dry surface of an agar plate. C) Directcell-to-cell contact is required for this process, and this is more likely tobe achieved in the fluid liquid format than on an agar plate (especially forrelatively non-motile types of bacteria). D) Trick question—it can take place with the same degree of efficiency on either format. It doesn't matter! E) Agitation is only needed if the bacteria are known to be non-motile and can't move around on a solid medium. Otherwise, it doesn't really matter what type of medium is used as long as it contains chemicals to make cells competent.

A) the mutant but notthe parental cell type will grow.

Direct selection involves inoculating cells onto growth media on/in which A) the mutant but notthe parental cell type will grow. B) the mutation will be reversed. C) the nutrients necessary for mutation to occur are present. D) the mutagen is present. E) histidine has been added.

false

Double-stranded DNA enters the recipient cell during transformation. ⊚ true ⊚ false

true

Each gene mutates at a characteristic frequency. ⊚ true ⊚ false

A) Proofreading by DNA polymerase, glycosylase enzyme activities, excision repair, SOS repair

Every 24 hours, every genome in every cell of the human body is damaged 10,000 times or more. Given the possible DNA repair mechanisms, which order listed below would be most effective at repairing these as quickly as possible in order to prevent mutations from being carried forward in DNA replication? A) Proofreading by DNA polymerase, glycosylase enzyme activities, excision repair, SOS repair B) SOS repair, excision repair, glycosylase enzyme activities, proofreading by DNA polymerase C) SOS repair, proofreading by DNA polymerase, glycosylase enzyme activities, excision repair D) Glycosylase enzyme activities, SOS repair, proofreading by DNA polymerase, excision repair E) Proofreading by DNA polymerase, SOS repair,glycosylase enzyme activities, excision repair

true

F plasmids and oftentimes R plasmids are both able to code for production of a pilus. ⊚ true ⊚ false

C) conjugation.

Gene transfer that requires cell-to-cell contact is A) transformation. B) competency. C) conjugation. D) functional genomics. E) transduction.

true

Genomic islands can be identified by the fact that they have a different C-G content from the rest of the cell's genome. ⊚ true ⊚ false

C) act during DNA synthesis AND often result in frameshift mutations.

Intercalating agents A) act during RNA synthesis AND often result in frameshift mutations. B) act during RNA synthesis AND change the hydrogen bonding properties of nucleotides. C) act during DNA synthesis AND often result in frameshift mutations. D) change the hydrogen bonding properties of nucleotides AND always result in nonsense mutations. E) act during DNA synthesis AND always result in nonsense mutations.

D) Prototrophs and auxotrophs would both be killed by the penicillin; only Pen R mutants would grow and you would not enrich for auxotrophs.

If you were carrying out a penicillin enrichment culture andyou forgot to addpenicillinasebefore plating the sample onto nutrient agar, what would happen? A) You would get the same results whether you add this enzyme of not because penicillin naturally rapidly degrades in agar. B) The prototrophs would be able to grow on the agar plates but the auxotrophs would not. C) The auxotrophs would be able to grow on the agar plates but the prototrophs would not. D) Prototrophs and auxotrophs would both be killed by the penicillin; only Pen R mutants would grow and you would not enrich for auxotrophs. E) Prototroph and auxotroph colonies would change color from cream to red in the presence of the penicillin.

A) an F plasmid.

In conjugation the donor cell is recognized by the presence of A) an F plasmid. B) a Y chromosome. C) diploid chromosomes. D) an SOS response. E) an F plasmid AND diploid chromosomes.

C) from the same species of bacteria.

In conjugation, transformation, or transduction, the recipient bacteria is most likely to accept donor DNA A) from any source. B) from any species of bacteria. C) from the same species of bacteria. D) only through plasmids. E) from any source AND only through plasmids.

C) within the gene in question.

In order for insertional inactivation to occur, the transposon must be placed A) upstream from the gene in question. B) downstream from the gene in question. C) within the gene in question. D) randomly in the genome. E) in an intron.

A) is necessary to isolate auxotrophic mutants.

Indirect selection A) is necessary to isolate auxotrophic mutants. B) uses media on whichthe mutant but not the parental cell type will grow. C) uses media that reverses the mutation. D) uses media upon which neither the parental cell type nor mutant grows. E) is necessary to isolate his + prototrophs.

E) are the simplest type of transposon, code for a transposase enzyme, AND are characterized by an inverted repeat.

Insertion sequences A) are the simplest type of transposon, code for a transposase enzyme AND can produce pili. B) code for a transposase enzyme AND are characterized by an inverted repeat. C) are characterized by an inverted repeat AND can produce pili. D) can produce pili AND are the simplest type of transposon. E) are the simplest type of transposon, code for a transposase enzyme, AND are characterized by an inverted repeat.

D) No. If the antibiotics are given sequentially, there is a chance that resistance to either one may arise through mutation. When antibiotics are given simultaneously, thechance of resistance to two different antibiotics occurring is extremely low.

Is it as effective to take two antibiotics sequentially for an infection as it is to take them simultaneously, as long as the total length of time of the treatment is the same? A) No. There'salways one specific antibiotic that will be the most effective, and that is theonly antibiotic that should be used to treat a particular infection. B) Yes. Aslong as the length of time is the same, the two treatments should be essentially the same in terms of effectively eliminating the infection. C) No. Taken sequentially, the first antibiotic will select for the small portion of the population that will spontaneously mutate toward resistance. Then, the second antibiotic will do the exact same thing—selecting for resistance to the second drug from the few bacterial cells that remained from the first drug treatment. D) No. If the antibiotics are given sequentially, there is a chance that resistance to either one may arise through mutation. When antibiotics are given simultaneously, thechance of resistance to two different antibiotics occurring is extremely low. E) Yes. Each antibiotic will kill all the cells that are sensitive to it, no matter if the drugs are taken simultaneously or sequentially. The important thing is to take the medication for as few days as possible.

true

Mutations are likely to persist after SOS repair, but not after light-induced or excision repair. ⊚ true ⊚ false

D) competent.

Not all bacteria can take up DNA from the environment. Those that can are referred to as A) mutants. B) F −. C) F +. D) competent. E) transducers.

A) AATTAGTTC

On which of the following DNA strands would UV radiation have the most effect? A) AATTAGTTC B) AACCGGG C) TATATACG D) AUAUCGAU E) TATATACG AND AATTAGTTC

false

Organisms termed his - are considered prototrophic for histidine. ⊚ true ⊚ false

A) intercalating agents.

Planar molecules used as chemical mutagens are called A) intercalating agents. B) nitrous oxide. C) base analogs. D) alkylating agents. E) acids.

true

Plasmids often carry the information for antibiotic resistance. ⊚ true ⊚ false

C) A missense mutation is also called a synonymous mutation, meaning no change in the amino acid encoded.

Please select the INCORRECT statement regarding mutation. A) A reversion is a mutation that correctsa defect caused by an earlier mutation. B) A base substitution is a mutation in which the wrong nucleotide has been incorporated. C) A missense mutation is also called a synonymous mutation, meaning no change in the amino acid encoded. D) Insertionalinactivation is the disruption of a gene's function due to a DNA segment inserted into the gene. E) Spontaneous mutations are those that occur during the normal processes of a cell.

B) The restriction enzyme identifies and cuts a short nucleotide sequence in the bacterial genome.

Please select the INCORRECT statement regarding restriction-modification systems. A) The restriction enzyme identifies and cuts a short nucleotide sequence in the virus genome. B) The restriction enzyme identifies and cuts a short nucleotide sequence in the bacterial genome. C) The modification enzyme adds methyl groups to bacterial nucleobases recognized by the restriction enzyme. D) A restriction enzyme will not degrade DNA that has been methylated. E) The modification enzyme may add methyl groups to viral DNA.

C) is useful for identifying auxotrophs AND uses media on which the mutant will not grow but the parental cell typewill.

Replica plating A) is useful for direct selection of antibiotic resistance ANDis useful for identifying auxotrophs. B) uses media on which the mutant willgrow but the parental cell typewill notANDis useful for identifying prototrophs. C) is useful for identifying auxotrophs AND uses media on which the mutant will not grow but the parental cell typewill. D) is useful for identifying auxotrophs ANDuses media on which the mutant willgrow but the parental cell typewill not. E) is useful for direct selection of antibiotic resistance ANDis useful for identifying prototrophs.

C) transposons.

Segments of DNA capable of moving from one area in the DNA to another are called A) base analogs. B) intercalating agents. C) transposons. D) inverted repeats. E) mutagens.

C) Good and bad—they're very good at killing cancer cells, but they could also be dangerous to non-cancerous cells.

Strong chemical mutagens may be used to treat cancer cells. Is this a good or bad idea? A) Good—kill those cancer cells as quickly as possible to cure the patient! B) Bad—these mutagens will also affect the non-cancerous cells, possibly leading to new cancerous states! C) Good and bad—they're very good at killing cancer cells, but they could also be dangerous to non-cancerous cells. D) Bad—the cancer cells are already mutated. We don't want to mutate them more and make them more cancerous! E) Bad—the medications are toxic and will cause healthy normal microbiotsto become cancerous.

A) Genomic islandsare large DNA segments in a cell's genome that originated in other species; pathogenicity islands are genomic islands that code for factors that allow an organism to cause disease.

Select the CORRECT statement regarding genomic islands. A) Genomic islandsare large DNA segments in a cell's genome that originated in other species; pathogenicity islands are genomic islands that code for factors that allow an organism to cause disease. B) Genomic islandscode for factors that allow an organism to cause disease; pathogenicity islands are large DNA segments in a cell's genome that originated in other species. C) Genomic islandsare large DNA segments in a cell's genome that originated in other species; pathogenicity islands are genomic islands that code for factors that protect an organism from disease. D) Genomic islandsare large DNA segments in a cell's genome that move from one place to another; pathogenicity islands are genomic islands that code for factors that allow an organism to cause disease. E) Genomic islandsare large DNA segments in a cell's genome that originated in other species; pathogenicity islands are genomic islands that confer antibiotic resistance on an organism.

C) They may simply have a higher proportion of T nucleotides next to each other in their DNAthan other bacteria, leading to more possible dimers being formed AND they may have a weaker expression of photoreactivation enzymes, leading to formation of more thymine dimers.

Some bacteria have a higher incidence rate of thymine dimer mutations following exposure to UV light than others. What might be going on here to lead to this outcome? A) They may simplyhave a higher proportion of T nucleotides next to each other in their DNAsequences than other bacteria, leading to more possible dimers beingformed. B) They may simply have a higher proportion of T nucleotides next to each other in their DNA sequences than other bacteria, leading to more possible dimers being formed AND they may have a strongerexpression of photoreactivation enzymes, leading to formation of more thymine dimers. C) They may simply have a higher proportion of T nucleotides next to each other in their DNAthan other bacteria, leading to more possible dimers being formed AND they may have a weaker expression of photoreactivation enzymes, leading to formation of more thymine dimers. D) They may have astronger expression of photoreactivation enzymes, leading to more thyminedimers being formed and retained. E) They may have aweaker expression of photoreactivation enzymes, leading to more thymine dimersbeing formed and retained.

false

The Ames test determines antibiotic sensitivity of a bacterium. ⊚ true ⊚ false

B) phenotype.

The characteristics displayed by an organism in any given environment is its A) archaetype. B) phenotype. C) genotype. D) mutatotype. E) phenogene.

C) integrate fragments from the phage DNA in their own chromosomes and target for destruction any DNA that contains the same fragments in the future.

The clustered, regularly interspaced short palindromic repeats (CRISPR) system in bacterial cells has been called the "immune" system of bacteria. CRISPR protect bacteria from a repeat infection from the same phage because bacterial cells A) recognize proteins on the surface of the phage and secrete enzymes that digest the phage. B) recognize proteins on the surface of the phage and secrete proteins that block the binding of the phage. C) integrate fragments from the phage DNA in their own chromosomes and target for destruction any DNA that contains the same fragments in the future. D) modify the attachment sites for the phages so that new infections cannot take place. E) integrate fragments from the phage RNA in their own chromosomes and target for destruction any RNA that contains the same fragments in the future.

A) the genotype of bacteriathat lacka functional gene for histidine synthesis AND bacteria that are auxotrophic for histidine.

The designation his - refers to A) the genotype of bacteriathat lacka functional gene for histidine synthesis AND bacteria that are auxotrophic for histidine. B) the genotype of bacteriathat havea functional gene for histidine synthesis AND bacteria that requireaddition of histidine to the growth medium. C) the genotype of bacteriathat havea functional gene for histidine synthesis ANDbacteria that are auxotrophic for histidine. D) the genotype of bacteriathat lacka functional gene for histidine synthesis AND bacteria that have a hers gene. E) the genotype of bacteriathat lacka functional gene for histidine synthesis AND bacteria that do not requireaddition of histidine to the growth medium.

A) the matching chromosome may carry the correct version of the gene.

The diploid character of eukaryotic cells may mask the appearance of a mutation since A) the matching chromosome may carry the correct version of the gene. B) the matching chromosome may repairthe mutated gene. C) the mutation is usually reversible. D) the mutation may create inverted repeats. E) All answer choices are correct.

true

The restriction-modification system always has two genes involved, the cutting enzyme and the methylating enzyme. ⊚ true ⊚ false

C) mutation.

The source of variation among microorganisms that were once identical is A) antibiotic resistance. B) virulence factors. C) mutation. D) sigma factors. E) mutant.

A) a bacterial plasmid promoter that was similar to plant promoters.

The study of the crown gall tumor found A) a bacterial plasmid promoter that was similar to plant promoters. B) an R plasmid in plant cells. C) incorporation of the bacterial chromosome into the plant. D) incorporation of the plant chromosome into the bacteria. E) a bacterial plasmid promoter that was similar to plant terminators.

B) conjugation AND transposons.

The transfer of vancomycin resistance from Enterococcus faecalis to Staphylococcus aureus is thought to have involved A) conjugation AND transformation. B) conjugation AND transposons. C) transformation AND transduction. D) transduction AND transposons. E) transformation AND transposons.

D) SOS repair, photoreactivation repair, AND excision repair.

Thymine dimers are removed by A) cold-activated repair mechanisms. B) SOS repair ANDphotoreactivation repair. C) SOS repair AND excision repair. D) SOS repair, photoreactivation repair, AND excision repair. E) photoreactivation repair AND excision repair.

C) ground-up rat liver.

To increase the chance of detecting carcinogens in the Ames test, the test substance is treated with A) penicillin. B) heat. C) ground-up rat liver. D) reverse transcriptase. E) penicillin AND heat.

D) It doesn't matter—human cells don't have the enzymes needed for photorepair of thymine dimers.

To maximize the number of thymine dimer mutations following UV exposure, should you keep human cells in tissue culture in the dark, in the light, or does it matter at all? A) The dark—light will activate the photorepair systems that can break thymine dimers induced by UV light. B) The light—it's important to keep on producing the thymine dimers by keeping the plate exposed to light as much as possible. C) Alternatinglight and dark every hour to increase the chances that thymine dimers will form, but prevent photorepair systems from correcting them as they are formed. D) It doesn't matter—human cells don't have the enzymes needed for photorepair of thymine dimers. E) Alternatinglight and dark every 24 hours to increase the chances that thymine dimers will form.

true

Transposons may leave a cell by incorporating themselves into a plasmid. ⊚ true ⊚ false

B) It's highly likely that the two genes are located next to each other in thehost cell chromosome. Since transduction results from a packaging error or an excision error that occurs during the infection cycle of the bacteriophage , the genes must lie close to each other to be transduced into a new cell simultaneously.

Two bacterial genes are transduced simultaneously. What does this suggest about their proximity to each other within the original host genome? A) Nothing. It's highly likely that two separate virus particles were carrying each gene, and that they coinfected the new target cell at the same time.This could mean the two original genes might not even be from the same original host cell! B) It's highly likely that the two genes are located next to each other in thehost cell chromosome. Since transduction results from a packaging error or an excision error that occurs during the infection cycle of the bacteriophage , the genes must lie close to each other to be transduced into a new cell simultaneously. C) They must be within five gene lengths of each other, but not necessarily immediately adjacent. If they were immediately adjacent, the transposons that facilitate the transfer of genetic information between the two cells wouldn't be able to "jump" into them. D) It doesn't mean anything. Transduction relies on the ability of a cell to take up foreign DNA. It's possible here that the cell has simply taken up two separate bits of DNA at the same time from the surrounding environment. E) It's highly likely that one gene was on the chromosome but the other was actually on a plasmid; if those two elements are in one cell, genes can be transferred simultaneously.

A) It can be cultured on a selective medium containing histidine and penicillin.

What do you know about a bacterium that is His -/Trp +/Str S/Pen R? A) It can be cultured on a selective medium containing histidine and penicillin. B) It can be cultured on a selective medium containing tryptophan and streptomycin. C) It can be cultured on a selective medium containing streptomycin and penicillin. D) It cannot be cultured on a selective medium containing histidine and tryptophan. E) It can be cultured anaerobically on a selective medium containing histidine and penicillin.

A) The sum total of genes encoded by the various strains of a given species.

What is the pan-genome? A) The sum total of genes encoded by the various strains of a given species. B) The sum total of genes encoded by the various strains of Escherichia coli. C) DNA sequences found in all strains of a particular species. D) DNA sequences found in all strains of Escherichia coli. E) Segments of DNA that can move from one DNA molecule to another.

A) The cell would not recognize and destroy invading viral DNA.

What would be the outcome if a bacterial cell failed to make a Cas nuclease-crRNA complex? A) The cell would not recognize and destroy invading viral DNA. B) The cell would be unable to transcribe the CRISPR array. C) The cell would be unable to generate a CRISPR array. D) The bacterial cell would die. E) The cell would not be able to make a Cas nuclease.

C) Addition ordeletion of three consecutive nucleotides

Which change in a gene's DNA sequence would have the least effect on the eventual amino acid sequence produced from it? A) Deletion of two consecutive nucleotides B) Addition of one nucleotide C) Addition ordeletion of three consecutive nucleotides D) Substitution of one nucleotide AND addition of onenucleotide E) Addition of two consecutive nucleotides

D) It results from the incorporation of bacterial plasmid DNA into the plant chromosome.

Which is TRUE about a crown gall tumor? A) It is a unique viral infection of plants. B) It results from the transfer ofa transposonto the plant. C) It results from an Agrogallerium infection of the plant. D) It results from the incorporation of bacterial plasmid DNA into the plant chromosome. E) It results from the incorporation of plant plasmid DNA into the bacterial chromosome.

D) It removes both strands in the mismatch area.

Which is not true about mismatch repair? A) It uses an endonuclease. B) It requires DNA polymerase and DNA ligase. C) It uses methylation of the DNA to differentiate between strands. D) It removes both strands in the mismatch area. E) It fixes errors missed by the proofreading of DNA polymerase.

B) If the mutation ratetoantibiotic A is 10 -9per cell division, and to antibiotic B is 10 - 6per cell division, the probability of the cell being resistant to both medications is 10 -15.

Which of the following statements about spontaneous mutation is TRUE? A) A single mutation is common but a double mutation is very rare. B) If the mutation ratetoantibiotic A is 10 -9per cell division, and to antibiotic B is 10 - 6per cell division, the probability of the cell being resistant to both medications is 10 -15. C) If the mutation ratetoantibiotic A is 10 -9per cell division, and to antibiotic B is 10 - 6per cell division, the probability of the cell being resistant to both medications is 10 -54. D) A frameshift mutation in which three nucleotides are added is less likely to impact a cell that a frameshift mutation in which two nucleotides are deleted. E) A transposon may insertionally inactivate a gene when it jumps from one place in a genome to another.

C) cause breaks in DNA molecules.

X-rays A) have no effect on DNA. B) cause thymine trimers. C) cause breaks in DNA molecules. D) make the DNA radioactive. E) destroy lipopolysaccharide.

A) phase variation.

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. Youaresomewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzaeis common in thecountry to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia.You do some research on the geneticsofthis pathogen. H. influenzaehas genes that it needs to make pili for attachment to host cells. These pili genes are not always expressed; sometimes the bacterium turns them off and does not produce pili. This is an example of A) phase variation. B) antigenic sensing. C) two-component control. D) transduction. E) gene splicing.

C) It is a point mutation—a single base pair is altered, causing the change of one amino acid in the protein that does not affect the function of that protein.

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. Youaresomewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzaeis common in thecountry to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia.You do some research on the geneticsofthis pathogen. On further reading, you learn that strains of H. influenzaevary genotypically. Many of them have synonymous mutations. Select the TRUE statement regarding this type of mutation. A) It is a point mutation—a single base pair is altered, causing the change of one amino acid in the protein that changes the function of that protein. B) It is a point mutation—a single base pair is altered, causing the change of one amino acid in the protein that stops the correct formation of a protein. C) It is a point mutation—a single base pair is altered, causing the change of one amino acid in the protein that does not affect the function of that protein. D) It is a frameshift mutation—base pairs are added or deleted, causing the change of one or more amino acids in the protein but does not affect the function of that protein. E) It is a point mutation—several base pairs are altered, causing the change of many amino acids in the protein that completely changes the function of that protein.

true

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. Youaresomewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzaeis common in thecountry to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia.You do some research on the geneticsofthis pathogen. Penicillin affects peptidoglycan synthesis. Pneumonia caused by penicillinresistant H. influenzae could likely be treated with an antibiotic that targets protein synthesis. ⊚ true ⊚ false

B) transformation.

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. Youaresomewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzaeis common in thecountry to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia.You do some research on the geneticsofthis pathogen. What concerns you most about the strain of H. influenzaethat you may be exposed to while you are away is antibiotic resistance. The genes for resistance can be acquired by this organism as naked DNA from the environment, an example of A) conjugation. B) transformation. C) induced mutation. D) vertical gene transfer. E) transduction.

B) Transformation is the uptake of "naked" DNA from the environment.

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. Youaresomewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzaeis common in thecountry to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia.You do some research on the geneticsofthis pathogen. Which of the following statements is CORRECT regarding transformation? A) DNA is transferred from one bacterial cell to another by means of a bacteriophage. B) Transformation is the uptake of "naked" DNA from the environment. C) Transformation involves the formation of a sex pilus through which plasmid DNA is shared between bacteria. D) Transformation depends on a donor cell containing an F plasmid and a recipient cell that does not. E) Transformation is a process that depends on physical contact between two bacterial cells.

D) The bacteria in the colonies are His +, Val +, Trp +, Leu +.

You mix two bacterial stains in a tube of glucose-salts agar. One strain is His −, Val −, while the other strain is Trp −, Leu −. You previously showed that neither strain grows on glucose-salts agar. After incubating the tube, you plate a sample onto a new glucose-salts agar plate. Several colonies grow. What do you know is TRUE about these colonies? A) The bacteria in the colonies are His −, Val −, Trp +, Leu +. B) The bacteria in the colonies are His −, Val +, Trp +, Leu +. C) The bacteria in the colonies are His −, Val −, Trp −, Leu −. D) The bacteria in the colonies are His +, Val +, Trp +, Leu +. E) The bacteria in the colonies are His +, Val +, Trp +, Leu +, Pen R.

A) UV radiation does not appear to cause mutation in D. radiodurans.

You are completing a research project for a Microbiology honors class. You are working with two bacteria: E. coli and Deinococcus radiodurans. You inoculate each organism onto TSA plates, and you then expose the plates to ultraviolet (UV) radiation for a specified time. You then incubate the plates overnight at 37oC for 24 hours, after which you count the number of colonies on each plate. Your results are shown in the table. Consider your results and select the CORRECT statement. A) UV radiation does not appear to cause mutation in D. radiodurans. B) E. coli and D. radiodurans are equally sensitive to UV radiation. C) UV radiation effectively eliminated 90% of the D. radiodurans cells. D) E. coli is able to repair any mutations caused by UV exposure. E) UV radiation effectively eliminated 80% of the E. coli cells.

A) They distort the DNA molecule, and stop replication and transcription. Without repair, the cell dies.

You are completing a research project for a Microbiology honors class. You are working with two bacteria: E. coli and Deinococcus radiodurans. You inoculate each organism onto TSA plates, and you then expose the plates to ultraviolet (UV) radiation for a specified time. You then incubate the plates overnight at 37oC for 24 hours, after which you count the number of colonies on each plate. Your results are shown in the table. How do thymine dimers cause the death of bacteria? A) They distort the DNA molecule, and stop replication and transcription. Without repair, the cell dies. B) They distort RNA molecules, and stop transcription and translation. Without repair, the cell dies. C) They causes single- and double-stranded breaks in DNA, preventing replication. Without repair, the cell dies. D) They insert between adjacent pairs of nucleotides, leading to frameshift mutations that always kill a cell. E) They alter the base-pairing properties of all the nucleotides, so that the pairing becomes A-C and G-T; this always kills a cell.

A) E. coli and D. radiodurans not exposed to UV at all (0 s).

You are completing a research project for a Microbiology honors class. You are working with two bacteria: E. coli and Deinococcus radiodurans. You inoculate each organism onto TSA plates, and you then expose the plates to ultraviolet (UV) radiation for a specified time. You then incubate the plates overnight at 37oC for 24 hours, after which you count the number of colonies on each plate. Your results are shown in the table. In your experiment, what is the control? A) E. coli and D. radiodurans not exposed to UV at all (0 s). B) Exposing E. coli to UV while not exposing D. radiodurans to UV. C) Exposing D. radiodurans to UV while not exposing E. coli to UV. D) Exposing E. coli and D. radiodurans to UV for at least 80 s. E) Comparing growth of E. coli and D. radiodurans exposed to UV with growth of a different, unexposed organism.

C) covalent bonds between adjacent thymine nucleobases on the same strand of DNA.

You are completing a research project for a Microbiology honors class. You are working with two bacteria: E. coli and Deinococcus radiodurans. You inoculate each organism onto TSA plates, and you then expose the plates to ultraviolet (UV) radiation for a specified time. You then incubate the plates overnight at 37oC for 24 hours, after which you count the number of colonies on each plate. Your results are shown in the table. UV light exposure forms A) covalent bonds between the two strands of DNA. B) hydrogen bonds between the two strands of DNA. C) covalent bonds between adjacent thymine nucleobases on the same strand of DNA. D) covalent bonds between adjacent guanine and cytosine nucleobases on the same strand of DNA. E) hydrogen bonds between adjacent guanine and cytosine nucleobases on the same strand of DNA.

A) Thymine dimer; induced

You are completing a research project for a Microbiology honors class. You are working with two bacteria: E. coli and Deinococcus radiodurans. You inoculate each organism onto TSA plates, and you then expose the plates to ultraviolet (UV) radiation for a specified time. You then incubate the plates overnight at 37oC for 24 hours, after which you count the number of colonies on each plate. Your results are shown in the table. When bacteria are exposed to UV light, what type of mutation occurs and is it spontaneous or induced? A) Thymine dimer; induced B) Guanine trimer; induced C) Nucleotide substitution; spontaneous D) Insertional inactivation; induced E) Thymine trimer; spontaneous

B) The prototrophs are resistant to penicillin but the auxotrophs are sensitive to this antibiotic.

You make two agar plates: one is a nutrient agar plate (plate A) that contains histidine andpenicillin. The other is a glucose salts agar (plate B) that also contains penicillin. You inoculate a sample onto both plates using replica plating technique, incubate the plates, and compare the growth after 48 hours. There are 12 colonies on the nutrient agar plate and 11 colonies on the glucose salts medium. Which of the following statements is INCORRECT? A) The colony that is missing from plate B is an auxotroph that cannot synthesize histidine. B) The prototrophs are resistant to penicillin but the auxotrophs are sensitive to this antibiotic. C) Prototrophs and auxotrophs in this experiment are resistant to penicillin. D) Approximately 92% of the bacteria in the original sample are prototrophs. E) This experiment describes indirect selection of a mutant.