Midterm 2 practice questions
Cells growing in a rich medium will have a steeper log-phase slope than will those growing in a nutrient-poor medium. True False
True
During the stationary phase, bacteria continue to undergo binary fission. True False
True
Ethylene oxide gas is used to sterilize medical equipment that might be damaged by exposure to the heat of autoclaving. True False
True
Ionizing radiation can be used to sterilize some foods such as spices, meat, and fruits and vegetables. True False
True
Psychrotrophic organisms are often responsible for food spoilage in refrigerated foods. True False
True
The presence of organic matter, such as blood or saliva, may impair the action of antimicrobial chemicals. True False
True
Times required for sterilization in an autoclave are shorter than those required in a dry oven because moist heat penetrates biological specimens more effectively than does dry heat. True False
True
Why is binary fission more quick and efficient when compared to eukaryotic cell division? The formation of a septum requires little energy. Each parent cell produces two new daughter cells. Bacteria do not need to form a mitotic spindle nor dissolve a nuclear membrane. Cell walls of bacteria are assembled faster than cell walls found in eukaryotes.
Bacteria do not need to form a mitotic spindle nor dissolve a nuclear membrane.
Which bacterium is used with a recombinant Ti plasmid to introduce rDNA into plant cells? A.Staphylococcus B.Agrobacterium C.Bacillus D.Clostridium E.Escherichia
B.Agrobacterium
Which disinfectant acts by inactivating proteins by cross-linking with functional groups? A.bisphenols B.aldehydes C.alcohols D.peroxygens E.halogens
B.aldehydes
Transformation is the transfer of DNA from a donor to a recipient cell A.by a bacteriophage B.as naked DNA in solution C.by cell-to-cell contact D.by crossing over E.by sexual reproduction
B.as naked DNA in solution
Endospores are highly resistant to most biocides because A.they have waxy lipids B.they have a thick spore coat C.they have an LPS layer D.they have a lipid envelope E.they are covered by exopolysaccharides
B.they have a thick spore coat
Boiling is A.a method of dry heat sterilization B.more effective than autoclaving C.a method that kills most vegetative cells, but endospores can survive D.a method that uses temperatures above 100°C E.a method that kills by oxidation
C.a method that kills most vegetative cells, but endospores can survive
Vectors should have all of the following features EXCEPT A.selectable marker genes B.large enough to manipulate outside the cell C.be destroyed by the recipient cell D.preservation E.self-replication
C.be destroyed by the recipient cell
During translation, amino acids are joined by A.hydrogen bonds B.ionic bonds C.peptide bonds D.disulfide bonds E.metallic bonds
C.peptide bonds
The term microaerophile refers to an organism that A.does not use oxygen but tolerates it B.is killed by oxygen C.requires an oxygen concentration lower than in air D.requires oxygen to live E.grows better with oxygen, but can grow with no oxygen
C.requires an oxygen concentration lower than in air
When cell deaths match production, this is the A.death phase B.log phase C.stationary phase D.lag phase
C.stationary phase
If a single bacterium replicated every 30 minutes, how many bacteria would be present in 2 hours? 4 8 16 32 64
16
Starting with a single parent cell, how many cells would there be after four rounds of binary fission? 4 8 12 16 32
16
Place the following events of lagging strand DNA synthesis in order: DNA polymerase synthesizes new DNA strand in the 5' to 3' direction. Primase adds an RNA primer. Okazaki fragments are joined together. RNAse removes the RNA primer. 1, 2, 3, 4 2, 1, 4, 3 1, 2, 4, 3 2, 1, 3, 4
2, 1, 4, 3
According to the chart, how many amino acids are coded for by codons? 3 20 64 61
20
If you begin with three cells, how many cells would you have after three rounds of division? 6 9 12 18 24
24
How many codons code for the termination of transcription? 1 3 64 61
3
Put the following steps of bacterial replication in order, starting from a parent cell. Cell elongation Septum formation Chromosome replication Separation of daughter cells 3, 1, 2, 4 3, 2, 1, 4 4, 3, 1, 2 2, 4, 3, 1 1, 4, 3, 2
3,1,2,4
Which of the following is an example of a nucleoside analog? benzopyrene nitrous acid 5-bromouracil ethidium bromide arcidine orange
5-bromouracil
Alcohol is most effective when used as a __________ solution. 25% 60% 70% 95% 100%
70%
The DRT for a particular bacterial species at 60°C is 30 minutes. How long would it take at this temperature to remove 99.9% of this bacterial population? 10 minutes 30 minutes 60 minutes 90 minutes 120 minutes
90 minutes
Aerotolerant organisms can grow in the presence of oxygen because their cell walls protect them from toxic products of oxygen. True False
False
All bacteria die at once when they are exposed to heat or chemical treatment. True False
False
All restriction enzymes produce short stretches of single-stranded DNA called "sticky ends." True False
False
Candle jars work well for cultivating anaerobic bacteria. True False
False
DNA can be introduced into plant cells only if the cell wall is first removed. True False
False
If a foreign gene inserted into a plasmid inactivates the beta-galactosidase gene, a bacterium containing that plasmid would form blue colonies on the X-gal medium. True False
False
In a direct microscopic count, dead cells are easily differentiated from live cells. True False
False
Iodine is one of the least effective antimicrobial chemicals, effective only against certain very sensitive strains of bacteria. True False
False
Microaerophiles do NOT require oxygen for growth. True False
False
Real-time PCR differs from traditional PCR in that real-time PCR amplification is monitored by gel electrophoresis. True False
False
Soap is ineffective in killing bacteria. Therefore, hand washing is a rather ineffective measure in preventing disease transmission. True False
False
Turbidity, or cloudiness, of cell cultures measured by spectrophotometry is useful in detecting very small amounts of microbial contamination in liquids. True False
False
UV radiation and X-ray radiation are similar in that they damage DNA and have a high penetrating power. True False
False
The biosafety level (BSL) for a lab that has no special precautions is A.BSL-1 B.BSL-2 C.BSL-3 D.BSL-4
A.BSL-1
Viruses with a lipid envelope are highly resistant to disinfectants and antiseptics. True False
False
When the spread plate technique is used to inoculate culture media, some colonies are expected to form within the agar. True False
False
Yeasts can only be genetically engineered to express foreign, prokaryotic genes. True False
False
Osmotic pressure suppresses microbial growth by A.causing plasmolysis B.oxidizing DNA C.dissolving lipids D.trapping cells on a filter E.denaturing proteins
A.causing plasmolysis
What type of mutagen is structurally similar to normal bases but has different base-pairing properties? A.nucleoside analog B.acridine C.nitrous acid D.ionizing radiation E.UV radiation
A.nucleoside analog
In the polymerase chain reaction (PCR), what happens during the annealing step? A.primers bind to the DNA template B.mRNA is synthesized C.DNA strands separate into single strands D.complementary strand of DNA is synthesized E.DNA is degraded
A.primers bind to the DNA template
If you determine that a microbe has an optimal growth temperature of 55°C, it would be classified as a A.thermophile B.psychrophile C.mesophile D.hyperthermophile E.psychrotroph
A.thermophile
The term trace elements refers to a. the elements CHONPS b. vitamins c. nitrogen, phosphorus, and sulfur d. small mineral requirements e. toxic substances
d. small mineral requirements
During which phase of bacterial growth will the number of dying cells exceed the number of new cells being made? lag phase log phase stationary phase death phase
death phase
Blood agar used to observe hemolysis or clearing around Streptococcus pyogenes colonies is an example of a/an __________. differential media selective media reducing media isolation media enrichment media
differential media
All of the following methods are used for food preservation EXCEPT __________. dessication osmotic pressure deep freezing direct flaming commercial canning
direct flaming
Which of the following is NOT a step in bacterial cell division? replication of the genetic material cell elongation disappearance of nuclear envelope splitting apart of two new daughter cells
disappearance of nuclear envelope
Which of the following temperatures would most likely kill a mesophile? a. -50 degrees c b. 0 degree C c. 9 degree C d. 37 degree C e. 60 degree C
e. 60 degree C
What type of mutation can change all subsequent amino acids following it? nonsense mutation missense mutation frameshift mutation silent mutation
frameshift mutation
Ethidium bromide can result in _________________. chromosomal breaks. base mismatching during DNA replication. frameshift mutations via insertion or deletion of nucleotides. thymine dimers.
frameshift mutations via insertion or deletion of nucleotides.
You contaminate the kitchen counters with Salmonella enterica in chicken blood and expose it to a variety of treatments to study the survival of the bacteria on kitchen surfaces. The following DRT values were obtained: 2.0 minutes at 52°C; 3.7 minutes at pH 2.6; 13.3 minutes with 10 mM hydrogen peroxide; and > 35 days without treatment. Which treatment is most effective against S. enterica? heat (52°C) acid (pH 2.6) 10 mM hydrogen peroxide These are equivalent treatments. The most effective treatment cannot be determined from the given data.
heat (52°C)
CAU codes for ___________________. isoleucine. histidine. proline. tryptophan. serine.
histidine.
Which of the following terms are mismatched? extreme halophiles; 30% salt hyperthermophiles; 0 C acidophiles; low pH psychrophiles; 0°C extreme thermophiles; 100°C
hyperthermophiles; 0 C
Which of the following chemotherapeutic agents would prevent the formation of THF in a bacterial cell? chloramphenicol fluoroquinolone sulfonamide penicillin
sulfonamide
All of the following are true of the plate count method EXCEPT that it __________. involves cell plating and growth is the most commonly used method for assay of bacterial cell number measures number of viable cells takes less than 12 hours to complete is dependable
takes less than 12 hours to complete
A disadvantage of using E. coli to produce recombinant proteins for human pharmaceuticals is the possibility of endotoxin contamination. True False
true
Clinical trials are currently underway using RNA interference (RNAi) to silence a gene found in certain genetic disorders. True False
true
In protoplast fusion, a chemical can induce fusion between the two wall-less cells. True False
true
Many genetically modified bacteria are programmed with a self-destructive gene that will eventually destroy the organism. True False
true
Viral DNA is an important cloning vector because it can typically be combined with relatively large pieces of DNA. True False
true
Which of the following is NOT a method used for the direct measurement of microbial growth? turbidity the most probable number (MPN) method filtration spread plates serial dilutions
turbidity
Packages of milk and coffee creamers may be stored without refrigeration if they have been sterilized by __________. autoclaving treatment with phenol boiling ultra-high-temperature (UHT) treatment high-temperature short-time (HTST) pasteurization
ultra-high-temperature (UHT) treatment
Hypertonic environments cause: a. Plasmolysis b. Osmotic lysis c. Depletion of nutrients d. Increased pH
a. Plasmolysis
Antibiotic resistance due to horizontal gene transfer could involve which of the following? the uptake of DNA from its surroundings transfer of R plasmid via bacterial conjugation DNA mutation making an altered enzyme that can degrade the antibiotic #1 and # 2 #1 and #3
#1 and # 2
The modification of existing cell structures could result in the resistance to which antibiotics? tetracycline sulfonamide penicillin #1 and #2 all of the above
#1 and #2
Which of the following statements correctly differentiates a genomic library from a cDNA library? A genomic library contains only noncoding DNA sequences, whereas a cDNA library contains only coding sequences. Genomic libraries contain only those genes that a cell is currently expressing, whereas cDNA libraries contain all of the cell's genes, whether expressed or not. Genomic libraries are prepared from eukaryotes, and cDNA libraries are prepared from prokaryotes. A genomic library contains fragments of the entire DNA in an organism's genome. A cDNA library contains the coding sequences of eukaryotic genes (minus the introns). cDNA libraries can be used for sequencing, but they cannot be transcribed and translated. Genomic libraries can be used for sequencing and for production of the desired protein product.
A genomic library contains fragments of the entire DNA in an organism's genome. A cDNA library contains the coding sequences of eukaryotic genes (minus the introns).
Which of the following is a good target for a chemotherapeutic used to treat a bacterial infection? bacterial ribosomes the peptidoglycan cell wall DNA gyrase A, B, and C are all good targets none of the above
A, B, and C are all good targets
Which of the following can result once the recombinant DNA molecule has been made? It is inserted into a host cell. It is copied many times inside a host cell. It can be transcribed and then translated into a desired protein. All of the above actions can result. None of the above actions can result.
All of the above actions can result.
Why is it useful to plot bacterial growth on a logarithmic graph? You cannot determine the number of cells with a linear graph. The number of cells dividing is equal to the number of cells dying, which can be determined only by a logarithmic graph. Because the number of cells increases rapidly, a logarithmic graph allows you to visualize the complete growth curve. The generation times of bacteria are different from species to species.
Because the number of cells increases rapidly, a logarithmic graph allows you to visualize the complete growth curve.
Which of the following statements is true for binary fission? Binary fission results in the production of two genetically identical daughter cells. Replicated chromosomes are separated by attaching to a mitotic spindle. Daughter cells must mature before they are able to perform binary fission. Binary fission occurs as quickly as eukaryotic mitosis. Binary fission results in the production of one genetically identical daughter cell.
Binary fission results in the production of two genetically identical daughter cells.
Through metabolism, pathogens often produce acids that interfere with their own growth. __________ are/is added to media to control pH changes. Buffers Vinegar pH indicators Saline Growth inhibitors
Buffers
Which of the following statements about DNA replication is TRUE? A.DNA ligase separates the DNA strands B.The leading strand is synthesized discontinuously C.Synthesis of the new strand is initiated by a DNA primer D.DNA polymerase adds nucleotides to the 3' end of the growing strand E.RNA polymerase joins Okazaki fragments
D.DNA polymerase adds nucleotides to the 3' end of the growing strand
Which of the following is NOT a therapeutic application of DNA technology? A.subunit vaccines B.gene therapy C.RNAi D.creating drought-resistant plants E.insulin production in E. coli
D.creating drought-resistant plants
The most probable number (MPN) method A.measures the cloudiness of a bacterial suspension B.uses a special microscope slide C.collects bacteria on a filter D.uses multiple tubes and a statistical table E.counts the colonies on a plate
D.uses multiple tubes and a statistical table
Transposons are _________________________. enzymes that can move from one location in the DNA to another. DNA fragments that can move from one location in the DNA to another. proteins that move from one cell to another. DNA fragments that move from one cell to another.
DNA fragments that can move from one location in the DNA to another.
What is the role of DNA helicase in DNA replication? DNA uses DNA to get energy from ATP. DNA helicase synthesizes new strands of DNA. DNA helicase uses the energy from ATP to break the hydrogen bonds between two DNA strands, thereby "unzipping" the molecule. DNA helicase stabilizes the single strands of DNA during replication.
DNA helicase uses the energy from ATP to break the hydrogen bonds between two DNA strands, thereby "unzipping" the molecule.
Which enzyme(s) can synthesize new strands of DNA? primase DNA polymerase ligase #1 and #2 all of the above
DNA polymerase
The process of copying DNA prior to cell replication is known as _____________. RNA replication. DNA replication. DNA translation. DNA synthesis. DNA transcription.
DNA replication.
Some microbes are very resistant to antimicrobial chemicals. Which of the following would be the easiest to kill? Mycobacterium tuberculosis Clostridium endospores E. coli. Pseudomonas aeruginosa cysts of protozoa
E. coli.
What is commercial sterilization? A.removal of vegetative pathogens from nonliving surfaces B.an agent that kills microbes, but not spores C.lowering microbial counts on eating utensils D.removal of vegetative pathogens from living tissue E.enough heat to kill endospores of Clostridium botulinum in canned goods
E.enough heat to kill endospores of Clostridium botulinum in canned goods
The method of shooting DNA coated particles into plant cells is called A.transformation B.microinjection C.protoplast fusion D.electroporation E.gene gun
E.gene gun
In order to turn on the gene expression of an inducible operon, an inducer must bind to the A.promoter B.operator C.RNA polymerase D.corepressor E.repressor
E.repressor
DNA synthesis occurs in which direction? From 5' to 3' on the leading strand and 3' to 5' on the lagging strand. From 5' to 3' on the lagging strand and 3' to 5' on the leading strand. From 3' to 5' on both the leading and lagging strands. From 5' to 3' on both the leading and lagging strands.
From 5' to 3' on both the leading and lagging strands.
What is a potential source of mutations from ionizing radiation? Ions and free radicals resulting from ionizing radiation can break chromosomes. Ionizing radiation can result in nucleoside analogues mispairing with the normal DNA sequence. Ionizing radiation can result in the formation of thymine dimers. Ionizing radiation can cause the addition or removal of bases, resulting in a mutation.
Ions and free radicals resulting from ionizing radiation can break chromosomes.
How does the DNA polymerase know which nucleotide triphosphate to add to the growing strand? It does not; it is a random process that results in genetic diversity for the offspring. It hydrogen-bonds the nucleotide to the parental strand, pairing adenines to thymines and guanines to cytosines. It hydrogen-bonds the nucleotide to the parental strand, pairing adenines to cytosines and guanines to thymines. It hydrogen-bonds the nucleotide to the RNA primer made by primase, pairing adenines to thymines and guanines to cytosines.
It hydrogen-bonds the nucleotide to the parental strand, pairing adenines to thymines and guanines to cytosines
Why is primase essential for DNA replication? It removes the RNA left from the DNA replication process. It provides a 3' end of the newly synthesized strand, allowing DNA polymerase to begin copying DNA. It provides the RNA that is an essential part of the newly copied chromosome. It repairs the gaps between DNA fragments during lagging strand synthesis.
It provides a 3' end of the newly synthesized strand, allowing DNA polymerase to begin copying DNA.
Which of the following is NOT true of the polymerase chain reaction (PCR)? Large amounts of DNA must be isolated from the source organism. Short pieces of DNA called primers are added to the reaction mixtures. A heat-stable DNA polymerase is used in the reaction process. Billions of copies of a DNA sequence are made in a few hours. An automated thermocycler is used to heat and cool the reaction samples.
Large amounts of DNA must be isolated from the source organism.
How might a mutation result in antibiotic resistance? It facilitates R-plasmid transfer during bacterial conjugation. Mutations could allow DNA fragments to be taken up by cells. Mutations allow for bacteriophages to spread DNA to other bacteria. Mutations can result in a modification of an enzyme that could interfere with the action of the antibiotic.
Mutations can result in a modification of an enzyme that could interfere with the action of the antibiotic.
You are preparing a medium for growing fastidious bacteria and must add several heat-labile solutions of growth factors. Which of the following is an appropriate strategy for preparing and sterilizing this medium? Pasteurize the medium. Prepare and autoclave the medium before adding the growth factors. Use UV radiation to sterilize this medium. Use dry heat to sterilize the medium. Prepare the medium, add the growth factors, and autoclave.
Prepare and autoclave the medium before adding the growth factors.
Which of the following might specifically be used as part of a reverse-genetics approach to studying a gene? PCR Southern blotting Ti plasmid RNA interference reverse transcriptase
RNA interference
Which of these statements is true for restriction enzymes? A different restriction enzyme must be used to open the vector DNA than to excise the gene sequence to be cloned. Any restriction enzyme can cut any piece of DNA. Restriction enzymes are useful in genetic engineering when they make staggered cuts in DNA. Each restriction enzyme is able to make a staggered cut at its recognition site. A given restriction enzyme will always recognize the same DNA sequence, but it will cut differently depending on the species of origin of the DNA.
Restriction enzymes are useful in genetic engineering when they make staggered cuts in DNA.
Which of the following characteristics is a hallmark of bacterial growth? After several rounds of division, the genetic diversity of the bacterial population will be very diverse. Bacterial growth is fast because all bacterial cells undergo mitosis. All daughter cells produced will be smaller than the parent. Since the number of bacterial cells double after each round of replication, the number of cells rapidly increases.
Since the number of bacterial cells double after each round of replication, the number of cells rapidly increases.
In a population of bacteria, how does presence of an antibiotic help resistant cells within that population? The antibiotic kills or inhibits competitors, allowing the resistant cell to grow without competition. The antibiotic is metabolized by the resistant cell, providing more energy for growth. The sensitive cells must devote energy to destroying the antibiotic, slowing their growth. The antibiotic mutates sensitive cells, making them incapable of growing.
The antibiotic kills or inhibits competitors, allowing the resistant cell to grow without competition.
What do all of these bacteria have in common? bacteria in the rumen of cattle and sheep bacteria growing in the middle ear in chronic otitis media bacteria growing on the teeth in dental plaque The bacteria are all halophiles. The bacteria are all thermophilic. The bacteria are most likely growing in biofilms. The bacteria are all obligate aerobes. The bacteria are all gram-positive.
The bacteria are most likely growing in biofilms.
Why do cells that are placed in fresh media not immediately enter logarithmic phase of growth? The number of cells that are made is equal to the number of cells that are dying, resulting in no net growth. Some cells are dying and must be eliminated prior to cell division Cells are preparing to enter a dormant state for long-term survival. The cells need to switch their metabolic state from a dormant one to an actively growing one.
The cells need to switch their metabolic state from a dormant one to an actively growing one.
Which is a mechanism that enables a bacterial cell to overcome the effects of sulfonamides? The enzyme targeted by sulfonamide can be modified to have an increased affinity for PABA. Beta-lactamases are secreted to destroy the sulfonamide. Efflux pumps remove the sulfonamide from the cell. Protein channels modify their specificity, preventing sulfonamide from entering the cell.
The enzyme targeted by sulfonamide can be modified to have an increased affinity for PABA.
Which of the following statements about efflux pumps is true? They work by bringing in molecules they normally synthesize from their environment to allow the affected metabolic pathway to continue. The greater number of efflux pumps a bacterial cell has, the more resistant to the antibiotic it will be. They change the chemical structure of the antibiotic. They can never be modified to broaden the spectrum of antibiotics they work against.
The greater number of efflux pumps a bacterial cell has, the more resistant to the antibiotic it will be.
Which of the following statements concerning DNA replication is true? The leading strand of DNA replication requires only one RNA primer. The lagging strand of DNA replication requires multiple RNA primers. The lagging strand of DNA replication requires only one RNA primer. The leading strand of DNA replication does not require an RNA primer.
The leading strand of DNA replication requires only one RNA primer. The lagging strand of DNA replication requires multiple RNA primers.
What is meant by semiconservative replication? The new copies of DNA contain one original strand of DNA and one new strand of DNA. Both the new DNA molecules are made up of new DNA. Both the new DNA and the parental DNA remain connected during DNA replication. The newly made DNA strand is made entirely of new DNA, while the parental DNA is conserved.
The new copies of DNA contain one original strand of DNA and one new strand of DNA.
What might happen if the cell does not have RNAse? The hydrogen bonding between the DNA strands would all be broken. The newly made chromosome would consist of DNA and RNA molecules. There would be gaps of missing DNA throughout the newly synthesized DNA. DNA polymerase would not have a 3' to begin DNA synthesis.
The newly made chromosome would consist of DNA and RNA molecules.
What must occur for an organism to pass its genetic information on to its offspring? The parental chromosome must be given to the offspring. The host chromosome must be degraded. The parent must copy its own DNA and provide a copy to its offspring. A novel DNA chromosome must be made by the parent cell and given to its offspring.
The parent must copy its own DNA and provide a copy to its offspring.
Adding salts to a solution increases osmotic pressure and is used to preserve food. True False
True
__________ is a compound found in antimicrobial soaps that targets gram-positive bacteria. Formaldehyde Sodium nitrate Hydrogen peroxide Mercuric chloride Triclosan
Triclosan
How do beta-lactamases help to overcome antibiotics with beta-lactam rings? They pump the antibiotics out of the cell. They modify the enzymes that these antibiotics act upon. They actively destroy the chemical structure of the antibiotic. They prevent the antibiotic from entering the cell.
They actively destroy the chemical structure of the antibiotic.
Which of the following represent a true statement about the resulting new daughter cells? Four new daughter cells result from one parental cell. They share characteristics of both parental cells. They are unable to divide. They are genetically identical to the parent.
They are genetically identical to the parent.
Which of the following statements regarding Okazaki fragments are true? They are composed of RNA. They are found on the leading strand of DNA replication. They are typically 1000 nucleotides in length. They are found on the lagging strand of DNA replication.
They are typically 1000 nucleotides in length. They are found on the lagging strand of DNA replication.
Why is a complex transposon containing an antibiotic resistance gene more likely to be copied than a simple insertion sequence when the host reproduces? They confer a survival advantage for the host. They allow host DNA replication to occur. They have more active transposase. They are larger.
They confer a survival advantage for the host.
What is unique about complex transposons? They code for a transposase. They have two simple transposons with another DNA sequence between them. They always integrate the DNA sequence in between the two simple transposons into the host DNA. They contain insertion sequences.
They have two simple transposons with another DNA sequence between them.
What is the function of stabilizing proteins? They use ATP to break the hydrogen bonds between the strands of DNA. They form the replication fork. They hold the separated strands apart and prevent their degredation.
They hold the separated strands apart and prevent their degredation.
What is the function of the connector proteins? They produce the Okazaki fragments. They allow DNA synthesis to occur from the 3' to 5' direction. They enable one parental DNA strand and one newly synthesized DNA strand to be held together. They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.
They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.
During the Southern blotting technique, what is the purpose of transferring the DNA fragments from the gel to a nitrocellulose filter? This step separates the two complementary DNA strands. This step prepares the DNA for digestion by restriction enzymes. This step selects and transfers only the genes of interest. This step attaches the DNA fragments to a permanent substrate, which then can be probed. This step prepares the DNA fragments for PCR.
This step attaches the DNA fragments to a permanent substrate, which then can be probed.
What effect would tetracycline likely have on an infecting bacterium? a reduction in protein synthesis by interfering with tRNA a weakened peptidoglycan layer disruption of the cell membrane inability to replicate DNA by blocking DNA gyrase
a reduction in protein synthesis by interfering with tRNA
Extreme halophiles require: a. High osmotic pressure b. Low osmotic pressure c. High pH d. Low pH
a. High osmotic pressure
Staphylococcus aureus is a facultative halophiles, this means it grows best on: a. Mannitol salt agar (7.5% NaCl) b. Nutrient agar
a. Mannitol salt agar (7.5% NaCl)
Molds and yeasts grow best between: a. pH 5-6 b. pH 6-7 c. pH 7-8
a. pH 5-6
Acidophiles grow best at: a. pH <5 b. pH >8
a. pH <5
Which of the following is NOT a step in Southern blotting? separation of DNA fragments by gel electrophoresis addition of heat-stable DNA polymerase digestion of sample DNA with restriction enzyme addition of a radioactive probe made from the gene of interest transfer of DNA fragments to filters
addition of heat-stable DNA polymerase
An organism that grows both in the presence and the absence of oxygen and uses oxygen when it is available is called a/an __________. anaerobe facultative anaerobe aerobe microaerophile aerotolerant anaerobe
aerotolerant anaerobe
The replication fork moves ___________. ahead of the newly synthesized DNA. toward the stabilizing proteins. opposite the direction of the DNA helicase. away from the direction of newly synthesized DNA.
ahead of the newly synthesized DNA.
Which of the following bacterial cell structures increases in size during binary fission? cell wall bacterial chromosome cell membrane cytoplasm both the cell wall and cell membrane all of the above
all of the above
Which of the following codes for leucine? CUU CUG UUA all of the above none of the above
all of the above
The process of making multiple copies of a DNA molecule is referred to as __________. transformation DNA fingerprinting protoplast fusion amplification hybridization
amplification
If a bacterium acquired an antibiotic resistance gene via conjugation, the DNA would most likely originate from where? a fragment of DNA in the environment a sensitive bacterial cell an R-plasmid a bacteriophage
an R-plasmid
When two DNA pieces cut with the same restriction enzyme are combined, sticky ends will __________. associate by complementary base pairing and hydrogen bonds associate because of DNA ligase associate by covalent bonds not associate associate only if they are double-stranded
associate by complementary base pairing and hydrogen bonds
An organism that has peroxidase and superoxide dismutase but lacks catalase in most likely an a. aerobe b. aerotolerant anaerobe. c. obligate anaerobe
b. aerotolerant anaerobe.
Most bacteria grow between a. pH 1-5 b. pH 6.5-7.5 c. pH 8-14
b. pH 6.5-7.5
Which of the following types 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
Some antimicrobial treatments kill microbes; some inhibit growth. Which term refers to an agent that inhibits bacterial growth? bacteriostatic germicidal fungicidal bactericidal homeostatic
bactericidal
If DNA ligase were NOT used in the creation of a recombinant plasmid, __________. hydrogen bonds between complementary bases could not form links between guanine and cytosine would not occur the bacterium to receive the recombinant plasmid would not be competent and thus would be unable to take up the plasmid links between adenine and thymine would not occur base-pairing would occur but the sugar phosphate backbone would not be connected
base-pairing would occur but the sugar phosphate backbone would not be connected
All of the following are examples of microbial control using heavy metals EXCEPT __________. algae control in swimming pools using copper sulfate antiseptic solution containing mercurochrome burn treatment using silver-sulfadiazine ointment benzoyl peroxide used for acne treatment mouthwash solution containing zinc chloride
benzoyl peroxide used for acne treatment
Most bacteria divide by which method? mitosis binary fission meiosis fusion of gametes
binary fission
When a bacterial cell reproduces by splitting into two daughter cells, the process is called __________. binary fission mitosis expansion budding regeneration
binary fission
Members of the genus Clostridium display the following properties: gram-positive bacilli endospore formation anaerobic growth Which of the following would be appropriate for the culture of members of this genus? sodium thioglycolate broth blood agar plate in a candle jar nutrient broth in a standard incubator blood agar plate in an anaerobe jar both a blood agar plate in an anaerobe jar and sodium thioglycolate broth
both a blood agar plate in an anaerobe jar and sodium thioglycolate broth
Which of the following is not a characteristic of biofilms? a. antibiotic resistance b. hydrogel c. iron deficiency d. quorum sensing
c. iron deficiency
Assume you inoculated 100 facultatively anaerobic cells onto nutrient agar and incubated the plate aerobically. You then inoculated 100 cells of the same species onto nutrient agar and incubated the second plate anaerobically. After incubation for 24 hours, 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
For the introduction of a genetically modified plasmid into E. coli, __________. no treatment is needed, because the cells are naturally competent a gene gun must be used protoplast fusion must be used microinjection must be used calcium chloride and heat shock can be used
calcium chloride and heat shock can be used
During the lag phase, __________. nutrients are depleted no cellular activity can be detected cells are decreasing in number cells are engaged in intense enzymatic activity changes in pH occur
cells are engaged in intense enzymatic activity
A culture medium consisting of agar, peptone, and beef-heart extract is a/an __________. differential medium chemically defined medium complex medium selective medium enrichment medium
complex medium
Which type of transposon would contain an antibiotic resistance gene? complex transposons simple transposons both neither
complex transposons
Recombinant DNA technology is used for all of the following EXCEPT ________. culturing unknown organisms insertion of genes from humans or plants into bacteria or viruses hepatitis-B-vaccine production using yeast cells human-insulin production by bacterial cells amplification of DNA for microbe identification
culturing unknown organisms
Sterilization is the __________. destruction of all microbial life reduction of microbial growth destruction of all forms of microbial life except endospores elimination of all gram-negative bacteria elimination of vegetative bacterial cells and fungal spores
destruction of all microbial life reduction of microbial growth
What serves as the template for DNA replication? the new DNA strands proteins that are associated with DNA replication RNA from the cell each of the original DNA strands
each of the original DNA strands
Which of the following are NOT major targets for action of antimicrobials? nucleic acids proteins enzymes flagella cell membranes
flagella
For Agrobacterium tumefaciens to be used to introduce foreign DNA into a plant cell, that DNA must first be __________. inserted in an A. tumefaciens plasmid other than the Ti plasmid inserted into the Ti plasmid of A. tumefaciens outside the T-DNA region isolated from the crown gall using the appropriate restriction enzyme inserted into the T-DNA region of the Ti plasmid of A. tumefaciens inserted into the main chromosome of A. tumefaciens
inserted into the T-DNA region of the Ti plasmid of A. tumefaciens
X-rays would be considered which type of mutagen? nucleoside analog nucleotide-altering chemical nonionizing radiation ionizing radiation
ionizing radiation
The replication fork __________________. is what results if the DNA strands begin to degrade. is the point where DNA helicase is "unzipping" the double-stranded DNA molecule. iIs the point where stabilizing proteins bind the single strands of DNA is another term for DNA replication.
is the point where DNA helicase is "unzipping" the double-stranded DNA molecule.
During which phase of bacterial growth would you see cell dividing most rapidly? lag phase log phase stationary phase death phase
log phase
In which phase of the growth curve is the population-doubling time fastest? stationary phase lag phase logarithmic decline phase log phase death phase
log phase
What phase of the cell cycle is extended in a chemostat? lag phase logarithmic decline phase stationary phase log phase death phase
log phase
Which of the following is NOT a step in binary fission? lysis of the existing cell wall invagination of the plasma membrane cell elongation replication of chromosomal DNA cross-wall formation
lysis of the existing cell wall
Bacteria growing in and on the human body, including normal microbiota as well as pathogens, are classified as __________. thermophilic and acidophilic mesophilic and acidophilic mesophilic and heterotrophic thermophilic and halophilic mesophilic and halophili
mesophilic and heterotrophic
AUG codes for _________________. methionine. stop codon. both of the above.
methionine.
Which type of radiation is LEAST effective in killing microbes? X rays high-energy electron beams ultraviolet rays microwaves gamma rays
microwaves
Tetracycline resistance is likely due to which mechanism? efflux pumps beta-lactamase modification of an enzyme modification of a porin importing of a molecule outside of the cell to allow a metabolic pathway to continue
modification of a porin
Which of the following is NOT a chemical requirement of all bacteria? molecular oxygen mineral elements nitrogen carbon sulfur
molecular oxygen
A chemical that can increase the rate of mutations is called a _______________________. carcinogen. mutagen. deletion. insertion.
mutagen.
A mutation that results in the presence of a stop codon in the middle of the genetic code is a _____________. missense mutation. silent mutation. nonsense mutation. frameshift mutation.
nonsense mutation.
How frequently does an error occur in DNA replication in the absence of a mutagen? one error for every 10,000,000 nucleotides copied one error for every 10,000 nucleotides copied one error for every 1,000,000,000 nucleotides copied one error for every 1,000,000 nucleotides copied one error for every 100,000 nucleotides copied
one error for every 1,000,000,000 nucleotides copied
An ampicillin-sensitive culture of E. coli is transformed with a plasmid that contains the gene of interest plus an ampicillin-resistant gene. If it is then plated on an ampicillin-containing growth medium, __________. only the lactose-positive bacteria will grow only the bacteria with the plasmid will grow no bacteria will grow only the ampicillin-sensitive bacteria will grow all gram-negative bacteria will grow
only the bacteria with the plasmid will grow
Niacin, when added to a medium, would be considered a/an __________. organic growth factor electron carrier carbon source enzyme cofactor reducing agent
organic growth factor
Which chemotherapeutic agent blocks the formation of peptide crosslinks in bacterial cell walls? penicillin rifampin sulfonamide tetracycline
penicillin
Which of the following is an example of a cloning vector? human growth hormone ribosomal RNA tick plasmid mosquito
plasmid
Recombinant DNA can be introduced into a host cell by any of the following methods EXCEPT __________. electroporation protoplast fusion microinjection polymerase chain reaction transformation
polymerase chain reaction
Which chemotherapeutic agent interferes with the integrity of the bacterial cytoplasmic membrane? tetracycline chloramphenicol polymyxin streptomycin
polymyxin
Which of the following infectious agents challenge the current sterilization strategies that have been accepted and in use for decades? prions HIV mycobacteria methicillin-resistant Staphylococcus aureus (MRSA) endospores
prions
Which of the following is LEAST likely to be damaged by exposure to gamma radiation? viruses bacteria fungi protozoa prions
prions
In the blue-white screening procedure, bacteria that are transformed with recombinant plasmid and cultured in media containing ampicillin and X-gal will __________. produce blue colonies produce white colonies not grow in this medium produce the enzyme beta-galactosidase grow more rapidly than cells without recombinant DNA
produce white colonies
Which of the following is NOT an advantage of obtaining the protein product called human growth hormone by recombinant DNA technology rather than extraction from cadavers? speed purity production of endotoxins cross contamination cost-effectiveness
production of endotoxins
An organism displays some growth at 4°C and at 25°C. However, it grows best at 20°C. This organism would be classified as a __________. halophile thermophile mesophile psychrotroph psychrophile
psychrotroph
Which of the following cuts DNA at specific sequences? restriction enzyme plasmids DNA ligase
restriction enzyme
Martin Lewis agar is an enriched media (containing heated blood) designed for the growth of Neisseria gonorrhea. Antibiotics are added to suppress the growth of normal microbiota that may be found in patient specimens, yet permit the growth of Neisseria gonorrhea. This medium would best be described as __________. nutrient agar differential media selective media reduced media broad spectrum media
selective media
A good cloning vector __________. should have a high concentration of guanine should be readily degraded in the host should have a gene or genes that allows for selection of transformed host cells should not be able to be cut by more than one restriction enzyme should not be capable of replication
should have a gene or genes that allows for selection of transformed host cells
Which mutation is the least likely to be harmful to a cell? nonsense mutation silent mutation frameshift mutation missense mutation
silent mutation
Base pair substitutions can result in what type(s) of mutation? silent mutation nonesense mutation silent, nonsense, and missense silent, frameshift, and missense missense mutation frameshift mutation
silent, nonsense, and missense
An antiseptic is used to remove microbes from __________. foods before canning them restaurant glassware skin before an injection toilet surfaces food preparation areas
skin before an injection
During which phase of growth would you find the highest number of total cells, both living and dead? lag phase log phase stationary phase death phase
stationary phase
Pasteurized milk in an unopened container spoils in the refrigerator. A sample reveals the presence of microorganisms. The most likely explanation is __________. the microbes that survived pasteurization were able to grow at 4°C. the microbes are pathogens pasteurization-resistant mutants developed after pasteurization the pasteurization process was ineffective the milk was pasteurized too long
the microbes that survived pasteurization were able to grow at 4°C.
Genetic technology has enabled screening for a variety of genetic conditions, and use of this technology is becoming more widely available. Which of the following is likely to become an important issue that will need to be addressed? the alteration of human phenotypes to prevent early disease the use of DNA analysis in anthropological studies the need for legislation to protect the privacy of individuals' genetic information the use of DNA analysis in criminal investigations
the need for legislation to protect the privacy of individuals' genetic information
Which of these is NOT a characteristic of the autoclave? the ability to sterilize solutions with endospores the use of moist heat the use of high pressures the requirement for long (hours) exposure times the use of high temperatures
the requirement for long (hours) exposure times
Why must the recipient plasmid be cut with the same restriction enzyme? to prevent the donor from receiving the same genetic information to allow for a site in the plasmid for the donor DNA to attach to remove the donor DNA from the plasmid all of the above none of the above
to allow for a site in the plasmid for the donor DNA to attach
What is the ultimate goal of recombinant DNA technology? to add plasmids to improve the organism to remove undesirable genes to add desirable genes
to improve the organism
Which of the following is NOT a purpose of genetic modification? to modify the characteristics of an organism to remove antibiotic resistant plasmids from bacteria to create proteins used in vaccines (e.g., hepatitis B vaccine) to create multiple copies of a gene of interest to create hormones such as insulin or human growth hormone
to remove antibiotic resistant plasmids from bacteria
All antibiotic-resistant pathogens____________________ will be killed by the antibiotic administered. will have mutations in their DNA. will not be killed or inhibited by the antibiotic. obtained their resistance from a bacteriophage. have R plasmids.
will not be killed or inhibited by the antibiotic.
Pasteurization was first used by Pasteur to control spoilage of __________. cheese wine yogurt canned foods milk
wine
The following may be listed on the ingredient list of your favorite snack food. Which of these products is NOT antimicrobial? potassium sorbate xanthan sodium benzoate sorbic acid calcium propionate
xanthan