Micro Test 2 (1-2)

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What are the products of semiconservative replication for a double-stranded DNA molecule?

Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.

Why is DNA replication essential for a cell?

An organism must copy its DNA to pass genetic information to its offspring.

What is the function of the parental DNA in replication?

It serves as the template for DNA replication.

Which enzyme breaks the hydrogen bonds during replication?

DNA helicase

How do stabilizing proteins work on the DNA?

They bind to the single-stranded DNA.

In which direction does the replication fork move?

It moves ahead of the newly synthesized DNA.

What ensures that the single strands of DNA do not come back together?

Stabilizing proteins

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands?

DNA is flexible.

What is the function of the connector proteins?

They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.

Which DNA strand is synthesized continuously?

Leading strand

Which of the following are terms associated with Okazaki fragments?

Lagging strand, DNA ligase, and discontinuous

Why is the DNA synthesis of the lagging strand considered discontinuous?

The synthesis is moving in the opposite direction from the replication fork.

Drag the labels onto the diagram to identify the components of replicating DNA strands.

A. parental dna B. dna polymerase C. leading strand D. lagging strand E. dna ligase F. replication fork

Drag the labels onto the diagram to identify the stages in which the lagging strand is synthesized.

1. DNA polymerase begins synthesizing the lagging strand by adding nucleotides to a short segment of RNA. 2. After each piece of the lagging strand is complete, it is released from DNA polymerase. 3. A different DNA polymerase replaces the RNA segments with DNA. 4. DNA ligase seals the gaps between the pieces, and eventually forms a new continuous strand.

Drag the labels onto the diagram to identify how nucleotides pair up. Labels can be used once, more than once, or not at all. (parental of DNA and adding nucleotides where both parental strands are templates)

A with T C with G

Which of the following build(s) new strands of DNA?

DNA polymerases

Which statement about DNA replication is CORRECT?

The leading strand is built continuously, and the lagging strand is built in pieces.

During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?


The molecule that seals the gaps between the pieces of DNA in the lagging strand is

DNA ligase.

Which statement about DNA replication is FALSE?

DNA ligase adds nucleotides to the lagging strand.

What was the significance of Frederick Griffith’s experiments with Streptococcus pneumoniae?

He showed that the DNA from strain S cells could transform strain R cells.

For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. What was the basis of this thinking?

Proteins have a greater variety of three-dimensional forms than does DNA.

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?


Chargaff’s analysis of the relative base composition of DNA was significant because he was able to show that

the amount of A is always equivalent to T, and C to G

Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?

the diameter of the helix

What kind of chemical bond is found between paired bases of the DNA double helix?


It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?

sequence of bases

In an analysis of the nucleotide composition of DNA, which of the following will be found?

A + C = G + T

Replication in prokaryotes differs from replication in eukaryotes for which of these reasons?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5′ to 3′ direction of one strand runs counter to the 5′ to 3′ direction of the other strand.

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive.

An Okazaki fragment has which of the following arrangements?

5′ RNA nucleotide, DNA nucleotide 3′

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

No replication fork will be formed.

Which enzyme catalyzes the elongation of a DNA strand in the 5′ →♦ 3′ direction?

DNA polymerase III

What determines the nucleotide sequence of the newly synthesized strand during DNA replication?

the nucleotide sequence of the template strand

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn

What is the function of DNA polymerase III?

to add nucleotides to the end of a growing DNA strand

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent

leading strands and Okazaki fragments.

Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3′ end of Okazaki fragments?

DNA polymerase I

Which of the following separates the DNA strands during replication?


Which of the following covalently connects segments of DNA?


Which of the following synthesizes short segments of RNA?


The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that

the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

The leading and the lagging strands differ in that

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Which of the following best describes the addition of nucleotides to a growing DNA chain?

A nucleoside triphosphate is added to the 3′ end of the DNA, releasing a molecule of pyrophosphate.

A new DNA strand elongates only in the 5′ to 3′ direction because

DNA polymerase can only add nucleotides to the free 3′ end.

What is the function of topoisomerase?

relieving strain in the DNA ahead of the replication fork

Which of the following help to hold the DNA strands apart while they are being replicated?

single-strand binding proteins

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

double-stranded DNA, 4 kinds of dNTPs, primers, origins

DNA is synthesized through a process known as _____.

semiconservative replication

In a healthy cell, the rate of DNA repair is equal to the rate of DNA mutation. When the rate of repair lags behind the rate of mutation, what is a possible fate of the cell?

The cell can be transformed to a cancerous cell.

A DNA strand with the sequence 3′ GTGAACTGC 5′ is complementary to the sequence


______________________ is the overall direction of two ____________________ strands of DNA relative to one another so that the _________________ run opposite of each other.

Antiparallel; complementary; 5′ to 3′ orientations

Which of the following characteristics of a chromosome would identify it as a prokaryotic chromosome rather than a eukaryotic chromosome?

It is a circular molecule.

All of the following are associated with nucleic acid structure EXCEPT

ionic bonds.

Which of the following is found at the 5 end of a DNA strand?

a phosphate group

The structure of DNA explains both its ability to encode genetic information and the way in which it is copied during cell reproduction.


The Ames test proves that a chemical is

mutagenic in Salmonella.

Which of the following is true of DNA replication?

An RNA primer is needed to begin DNA synthesis.

The Ames test involves exposure of a histidine requiring strain of Salmonella typhimurium. After the test, mutants grow on a medium that is histidine-free. These mutants are an example of

back mutation

Bacteria typically contain multiple chromosomes.


The sequence of the DNA "backbone is


Which is the largest among the followings?


The overall conclusion of the Hershey-Chase experiment was that

DNA was responsible for heredity

The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins do not. Why isn’t protein shape more regular like DNA?

All of the above

Drag the correct labels onto the nucleotides in the RNA transcript. Not all labels will be used.

U with A G and C together A with T

Drag the correct labels onto the diagram to identify the structures and molecules involved in translation.

A. mRNA B. small subunit of ribosome C. large subunit of ribosome D. amino acid E. tRNA F. anticodon

Drag the correct labels under the diagrams to identify the events of RNA processing.

1. A modified guanine nucleotide is added to the beginning of the RNA strand as a cap. 2. Segments of the RNA strand that do not actually code for the protein are removed. 3. Segments of the RNA that do code for the protein are reconnected. 4. Extra adenine nucleotides are added to the end of the RNA strand, forming a tail. 5. The completed messenger RNA (mRNA) leaves the nucleus.

Which of the following events occurs during transcription?

A molecule of RNA is formed based on the sequence of nucleotides in DNA.

Which of the following is a correct statement about mRNA?

mRNA moves from the nucleus to the cytoplasm following RNA processing.

The site of translation is

ribosomes in the cell cytoplasm.

Which one of the following does not play a role in translation?


Which of the following does not occur during RNA processing?

mRNA attaches to the small subunit of a ribosome.

Transcription produces which of the following?

mRNA, tRNA, and rRNA are all produced by transcription.

According to the animation, which of the following makes mRNA from the information stored in a DNA template?

RNA polymerase

Ribosomes contain which of the following?


Which of the following is involved in bringing amino acids to the ribosomes?


Which of the following can be translated into protein?


What is the initial target of RNA polymerase?

The promoter

RNA polymerase is guided by the

template strand of DNA.

RNA that has hydrogen bonded to itself forms a

stem loop

How would one increase the concentration of a particular polypeptide in a cell?

Increase the level of transcription

During elongation, how is the RNA synthesized?

5′ to 3′

What results from the process of translation?

A polypeptide

How is bacterial translation different from eukaryotic translation?

Bacteria can begin translation before transcription has terminated.

According to the animation, ribosomes move along the mRNA in which direction?

5′ to 3′

As shown in the animation, the start codon also codes for which amino acid?


How many codons code for the amino acid arginine?


GAU codes for

aspartic acid.

Which of the following amino acids is coded by only one codon?


What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A?

A stop codon would be introduced prematurely.

During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?

P site

How does the ribosome know if the entering charged tRNA is correct?

The anticodon on the tRNA base pairs to the codon on the mRNA.

Where would one find an uncharged tRNA molecule in a ribosome?

In the P and E sites

What kind of bond is formed when two amino acids join together?

A peptide bond

How is translation terminated?

When a protein called a release factor enters and binds to the A site

A student states that the trp gene is located at 26 minutes. What does this mean?

It takes 26 minutes for the gene to be transferred during conjugation.

If argG, argR, and argE are all required to make a cell able to metabolize arginine, how long would it take for an arg- recipient to become arg+?

87 minutes

If conjugation was allowed to be carried out for 25 minutes, which genes would be transferred to the recipient strain?


How does conjugation help geneticists map the genomes of bacteria?

It provides them with the relative positions of the genes on the chromosomes.

If gene X transferred at 99 minutes for E. coli, what conclusion could you make about gene X?

Gene X is close to the fertility factor on the Hfr chromosome, but is near the end of the chromosome transfer.

Thymine dimers result from

nonionizing radiation.

Which of the following might result in a frameshift mutation?


Which of the following describes how 5-bromouracil might create a mutation?

It can replace the base thymine, and can base pair with guanine rather than adenine.


increase the likelihood of mutations in DNA.

A nucleotide-altering chemical

can alter nitrogenous bases of DNA, resulting in incorrect base pairing.

How is DNA methylation used in DNA repair?

The mismatch-repair enzymes can use a lack of methylation to identify and remove newly synthesized DNA.

Which of the following repair enzymes cannot repair thymine dimers?

Mismatch-repair enzymes

Why is light required for photolyases?

The light provides the energy to break the bonds between the thymine dimers.

Which of the following repair mechanism(s) does not involve DNA polymerase?

Light-repair mechanism

What is considered to be the average natural mutation rate that occurs during DNA replication?

One in every billion nucleotides replicated

A mutation that affects the genotype of the organism but not the phenotype is called a

silent mutation.

A base insertion or deletion in the translated region of the gene may lead to

frameshift mutation.

A base substitution that changes a codon coding for an amino acid to a stop codon is called a

nonsense mutation.

How frequently do silent mutations occur?

One out of every three mutations

What process involves copying sequences of DNA nucleotides into sequences of RNA nucleotides?


An initiator transfer RNA (tRNA) binds to the __________ of the small ribosomal subunit during the initiation of translation.

P site

Identify the anticodon complementary to the start codon with sequence AUG.


Transfer RNA (tRNA) is responsible for transporting a(n) __________.

amino acid

The energy used to bind transfer RNA (tRNA) to a ribosome’s P site comes directly from __________.


The initiator transfer RNA (tRNA) in bacteria has the anticodon sequence UAC and transports the amino acid __________.


Nucleotide bases form __________ bonds with their complementary bases.


The first step in the initiation of translation involves the attachment of the __________ to the start codon of the messenger RNA (mRNA).

small ribosomal subunit

Label the figure to assess your knowledge of the lac operon.
Drag the appropriate labels to their respective targets.

Top Image: Below 3′: Transcription Below transcription: translation Beside repressor mRNA: RNA polymerase cannot bind Yellow bar: promoter Bottom Image: Green hexagons: Inducer (allolactose from lactose) Pink and green: Inactivated repressor Arrow from transcription proceeds: repressor cannot bind From red strand: mRNA for lactose catabolism brown: RNA polymerase

What is unique about transduction compared to normal bacteriophage infection?

Transduction transfers DNA from the chromosome of one cell to another.

How is generalized transduction different from specialized transduction?

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

A transducing phage

contains fragments of the host chromosome instead of the viral genome

When a transducing phage interacts with a new host cell,

the DNA from the previous host can recombine with the new host chromosome.

Competent cells are cells that

can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.

Mice that are injected with only the R strain of Streptococcus pneumoniae

stay healthy, because their immune systems can kill this strain easily.

What characteristic of the S strain allows it to evade the immune system of the mice?

The cells have a capsule.

What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells?

The R strain picked up the S strain DNA, enabling it to produce a capsule.

Which finding is most surprising from Griffith’s experiments?

S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.

Which type of transposon would contain a gene for transposase?

Both simple and complex transposons

How do complex transposons differ from simple transposons?

Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon .

A silent mutation is so named because __________.

it has no effect on the overall amino acid sequence

A new chemotherapeutic agent is developed that alters the structure of all thymines in DNA. These thymines are then misread during the production of mRNA. Which of the following could NOT result from this type of mutation?

frameshift mutation

While studying protein synthesis in the lab, you experimentally induce a mutation in a bacterium’s DNA. You assess the proteins in the mutated bacterium and find that one of them is significantly shorter than its wild-type counterpart. Based on this information, what type of mutation did you induce?

nonsense mutation

What is a nosocomial infection?

This is a hospital-acquired infection.

What term is used to describe bacterial cells that can naturally take up DNA from their environment?

competent cells

How can hospital personnel prevent the spread of resistant E. faecium throughout the hospital?

Hospital personnel should wash their hands when entering and leaving a patient’s room.

Which of the following is NOT used by bacteria to acquire new genetic material?

cross over

What does MDR mean?


What is the function of the conjugation pilus?

It pulls the F+ and F- cells together.

What is required by an F- cell to become an F+ cell?

F plasmid

What is the key difference between donor cells and recipient cells?

An F plasmid

What cellular macromolecule is the fertility factor comprised of?

Nucleic acid

At which point does a recipient cell become an F+ cell?
1. Fusion of the cell membranes
2. Attachment of the sex pilus
3. Transfer of the single stranded F factor
4. Pulling of donor and recipient cells together
5. Formation of the complementary strand of the F factor


How does an F+ cell differ from an Hfr cell?

Hfr strains have the F plasmid integrated into the chromosome.

Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?

Conjugation is typically disrupted before the fertility factor can be transferred.

Which of the following is a characteristic of an F+ cell?

Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.

What benefit does the F- strain receive from mating with an Hfr strain?

It acquires new, potentially beneficial genes from the Hfr strain.

Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate?

Conjugation does not result in the formation of new offspring.

What must occur for bacterial conjugation to take place?

The cells must come into contact with each other.

Which statement about conjugation is false?

Conjugation is a process of bacterial reproduction

Based on the animation, what is transferred during bacterial conjugation?

A bacterial plasmid

During infection, C. diphtheriae grows and multiplies within the upper respiratory tract. As each bacterial cell prepares for division the chromosome must be replicated so that each daughter cell receives a copy of the genetic information. The following statements summarize the major steps in replicating the bacterial chromosome. Arrange the statements in the correct order to describe the process of replication of the leading strand.
Place the following statements in the correct order of events for replication of the leading strand. (From first to last)

Double stranded DNA is unwound by helicase. Proteins bind to the DNA in order to stabilize the single strands. Primase synthesizes an RNA primer. DNA polymerase catalyzes formation of a sugar-phosphate bond between neighboring nucleotides. Hydrogen bonds form between the complementary bases.

During infection, C. diphtheriae expresses a variety of genes that are used to establish infection and cause disease. One of these genes encodes for diphtheria toxin. Expression of the toxin requires the genetic information contained in DNA be converted into protein. The 1st step in this process is transcription, in which DNA is converted into mRNA. The following is a short piece of the DNA sequence for diphtheria toxin (written 5′ to 3′): TAA GCG TAG AAC TTG. Which of the following sequences represents the mRNA (written 5′ to 3′) that will be generated from this template DNA sequence?


The major virulence factor produced by C. diphtheriae is diphtheria toxin. The production of diphtheria toxin during infection is controlled by a repressor, DtxR. The activity of DtxR is regulated by iron, which acts as a corepressor. During an infection, the levels of iron available in the tissues for use by C. diphtheriae are low. What effect will the decreased iron availability have on the production of diphtheria toxin

The lack of corepressor binding to DtxR will lead to a loss of repression and an increase in the production of toxin.

Diphtheria toxin kills eukaryotic cells by affecting translation. More specifically, the toxin prevents movement of tRNAs from the A site to the P site of the ribosome. Predict what the result(s) of this inhibition would be.

Protein synthesis will be interrupted because the peptide chain is inhibited from growing. New tRNAs will not be able to enter the ribosome.

The ability of C. diphtheriae to produce toxin is acquired via the process of specialized transduction. This is just one of the mechanisms that bacteria use to transfer genetic material to other bacteria, a process known as horizontal gene transfer. There are different mechanisms for horizontal gene transfer in bacteria, each with its own unique features.
For each of the following phrases, indicate whether it occurs during transformation, conjugation, generalized transduction, or specialized transduction by dragging it to the appropriate bin.

Transformation: Naked DNA is transferred from donor to recipient. Requires the recipient cell to be competent. Conjugation: Requires direct contact between bacterial cells, which is typically mediated by a sex pilus. Donor and recipient cells must be of an opposite mating type. Generalized transduction: A phage infects the bacterial cell, thereby transferring bacterial, plasmid, and/or viral DNA to the recipient. Specialized transduction: During phage infection, particular bacterial genes are transferred to the recipient.

What is one method by which you could insert DNA from one cell into another cell?


Which of the following is NOT a vector?

protoplast fusion

Which of the following methods uses DNA probes?

Southern blot

All restriction sites are palindromic. What does this mean?

The nucleotide sequences at the restriction sites are the same when read forward or backward.

What action do restriction enzymes employ?

They cut DNA.

What role do restriction enzymes serve in the prokaryotes that produce them?

They destroy viral DNA.

How are restriction enzymes named?

Each is named with letters referring to the genus, species, and strain of the source prokaryote and a Roman numeral denoting the order of its discovery.

Although blunt-ended DNA fragments are more difficult to join back together than are sticky ends, blunt ends have an advantage in that __________.

they can be recombined with blunt fragments produced by different restriction enzymes

Which of the following statements concerning sticky-ended fragments is most likely to be true?

Complementary sticky-ended fragments were probably cut by the same restriction enzyme

The restriction enzyme KpnII probably originated __________.

as the second discovered restriction enzymes from Klebsiella pneumoniae bacterium

In the laboratory, recombinant DNA technologists use restriction enzymes __________.

to cut specific genes from one organism for the purpose of inserting the genes into the DNA of another organism

Bt crops, including potatoes and cotton, are genetically engineered using laboratory techniques. Which of the following utilizes recombinant DNA technology to produce advantageous traits in the crops that are produced?

Genetically engineered crops have an advantageous gene from another organism inserted into their genome.

Bt crops are engineered in the lab to produce Bt toxins due to the presence of a bacterial gene from B. thuringiensis. Why is it advantageous for the plants to produce the Bt toxin?

Insects that normally destroy non-toxin-producing crops will be killed when they eat plants that do produce the toxin.

Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome?

The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.

Arrange the following statements in chronological order.

The Ti plasmid is isolated and prepared for the insertion of foreign DNA. The gene for Bt toxin is isolated from the bacterium and inserted into the plasmid. The plasmid is taken up by a bacterium. The bacterium is used to introduce the Bt toxin gene into the chromosome of plant cells. A single plant cell is chosen to produce a plant that now produces Bt toxin.

GM crops have raised issues among communities in which they are produced. Which of the following are concerns raised by the public about genetically engineered crops?

The Bt toxin could negatively affect the taste of the food that is produced from these crops. The Bt toxin could result in the death of non-pest species of insects. The Bt gene could ultimately make the plants pathogenic to humans.

A particular triplet of bases in the template strand of DNA is 5′ AGT 3′. The corresponding codon for the mRNA transcribed is

3′ UCA 5′.

The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except

DNA was the first genetic material.

Which of the following is true for both prokaryotic and eukaryotic gene expression?

RNA polymerase binds to the promoter region to begin transcription.

In which of the following actions does RNA polymerase differ from DNA polymerase?

RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript.

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes

excision of introns.

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

both C and D

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that

proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

What is the most abundant type of RNA?


From the following list, which is the first event in translation in eukaryotes?

the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

The tRNA that was in the A site moves into the P site.

When does translation begin in prokaryotic cells?

as soon as transcription has begun

Why might a point mutation in DNA make a difference in the level of protein’s activity?

It might substitute an amino acid in the active site.

In the 1920s Muller discovered that X-rays caused mutation in Drosophila. In a related series of experiments, in the 1940s, Charlotte Auerbach discovered that chemicals (she used nitrogen mustards) ave a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why do we test for its ability to induce mutation?

We want to prevent any increase in mutation frequency.

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

a deletion of 2 nucleotides

What is the effect of a nonsense mutation in a gene?

It introduces a premature stop codon into the mRNA.

Each of the following options is a modification of the sentence THECATATETHERAT. Which of the following is analogous to a frameshift mutation?


Of the following, which is the most current description of a gene?

a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

What does the operon model attempt to explain?

the coordinated control of gene expression in bacteria

The role of a metabolite that controls a repressible operon is to

bind to the repressor protein and activate it.

A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA:


A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

continuous transcription of the structural gene controlled by that regulator.

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to

cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

Which of the following seals the sticky ends of restriction fragments to make recombinant DNA?

DNA ligase

Which of the following separates molecules by movement due to size and electrical charge?

gel electrophoresis

The horizontal transfer process known as transduction

involves a virus.

In conjugation, F+ cells

contain an F plasmid.

Which of the following microbes produces a protein that kills a variety of insect pests?

Bacillus thuringiensis

Transgenic organisms

contain genes from other organisms.

If all the following DNA fragments were analyzed on an electrophoresis gel, which one would migrate farthest from the negative electrode?

250 base pairs

What do hyaluronidase and kinase have in common?

They are both enzymes involved in evading host defense.

According to your Concept Map, which of the following organisms exhibits antigenic variation?

N. gonorrheae

Which of the following virulence factors could directly prevent phagocytosis and/or phagocytic degradation?

all of the above

A patient acquires an infection by touching a contaminated door handle. Which mode of transmission best describes this scenario?

indirect contact transmission

A dog develops a diarrheal disease after drinking water from a creek during a hike with his owner. Which of the following best describes this method of disease transmission?

vehicle transmission

Plague is transmitted through the bite of an infected flea. Which of the following best describes this mode of transmission?

vector transmission

How was this carrier identified?

urine culture

Based on the data supplied, what was the approximate mortality rate for this outbreak?


What is the reservoir for this disease organism, Salmonella enterica serotype Typhi?


How could this epidemic be stopped without firing the worker?

Educate the worker about personal hygiene; use an outhouse or designated bathroom. Instruct him to thoroughly wash his hands with clean soap and water after using the facilities.

What are the clinical signs and symptoms of typhoid fever?

fever and rose-spotted rash

Match the term that describes the occurrence of disease as illustrated by the dots on the map.
Drag the appropriate labels to their respective targets.

Few dots around everywhere: endemic disease all dots in one spot: epidemic clusters of dots in different places: pandemic

The health of the patient

should be the primary concern of the healthcare worker.

How can surgeons help to limit nosocomial infections?

They should perform surgeries and invasive procedures only when absolutely necessary.

If a patient notices a healthcare worker not following suggested precautions,

they should immediately bring it to the attention of the healthcare worker.

Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections?


Which of the following statements is true regarding hand washing?

Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction.

According to the animation, surgical infections account for what percentage of nosocomial infections?


What type of nosocomial infection is likely to arise from intravenous catheterizations?


How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic?

Antibiotics can be used in aerosols, thereby entering the environment.

Why are invasive procedures likely to increase the risk of nosocomial infections?

These procedures allow microbes from the skin to enter the bloodstream of the patient.

How can health care workers reduce the occurrence of nosocomial infections?

Practice more stringent aseptic techniques

Which of the following would be considered a fomite?

An infected toy

Which of the following would be considered a vector?

A fly carrying disease from fecal matter to food

When aerosols containing pathogens spread disease from a distance of less than one meter, it is considered

contact transmission

Which of the following is considered a major category of transmission of disease?

Contact, vehicle, and vector transmission

Which is an example of vehicle disease transmission?

The presence of Listeria on undercooked chicken served for dinner

Epidemiology is defined as the study of

where and when a disease occurs, and how it is transmitted.

What is the role of epidemiology?

To learn how to treat and prevent various diseases.

Expected prevalence of a disease is

the expected occurrence of a disease based on past observations.

In the sixth segment of the animation, why is the disease epidemic in North America?

The disease occurs at a higher rate than what would normally be expected in this region

In the last segment of the animation, how many regions of the world experience the pandemic during April of year four?


In the last segment of the animation, when does the first epidemic occur?

January of year three

If a disease occurs at a fairly stable rate, it is said to be


When the diagnosis of tuberculosis was confirmed, this case became one of national interest. What happened?

Because tuberculosis is a notifiable disease, the physician should notify the hospital infectious control department, city/county public health departments → state pubic health department → CDC.

Three infants test positive for tuberculosis 12 weeks later. None of their family members test positive for TB. Which of the following designations best categorizes these cases?

These new cases would be exogenous nosocomial infections.

Which term best classifies tuberculosis?


Why was the nurse placed in respiratory isolation?

He was in respiratory isolation to prevent droplet transmission of tuberculosis to others.

What is the standard for tuberculosis surveillance in a hospital?

Mantoux skin test required annually

Which vaccination may cause a false positive skin test for tuberculosis?

BCG vaccine

This nurse’s condition worsened after medical treatment. Which specific medication is immunosuppressive?

aerosol corticosteroids

Why must the physicians wait 3 months to skin test the babies and their mothers?

Mycobacterium tuberculosis is a slow-growing organism and it takes the body time to mount a cell-mediated defense that can be detected by the skin test.

Which was the defining test that determined this nurse has an active case of tuberculosis?

the presence of acid fast bacilli in the sputum sample

Which of the following situations is NOT a way in which a baby acquires normal microbiota?

Microbes cross the placenta during pregnancy.

A protozoan and its resident bacteria invade the body of a worm. The bacteria release toxins and exoenzymes that immobilize and digest the worm, and the protozoan and bacteria absorb the nutrients produced. The relationship between the protozoan and the bacteria would best be described as


The bacterium that causes cholera is capable of living independently in freshwater. As a consequence, cholera epidemics primarily involve (nonliving/animal/zoonotic) reservoirs.


A reservoir is

a source of microbial contamination.

A strain of Neisseria gonorrhea has a mutation which has caused it to lose the ability to produce fimbriae and become less virulent as a consequence. What function has this pathogen lost?

the ability to adhere to cells of the body

Which of the following is transmitted by the parenteral route?

yellow fever

In which of the following do the mucous membranes serve as a portal of entry for disease?

A pathogen is introduced into the body when the person rubs the eye with contaminated fingers and the pathogen is washed into the nasal cavity by way of tears.

Chagas’ disease is transmitted by a bug with mouthparts that penetrate blood vessels. Which type of exposure does this represent?

parenteral route

Which of the following combinations of pathogen and virulence factor is correct?

Streptococcus pyogenes and protein M

Which of the following is the correct sequence of a disease process?

incubation, prodromal period, illness, decline, convalescence

Among the virulence factors produced by Staphylococcus aureus are hemolysin, coagulase, hyaluronidase, and enterotoxin. Which of these factors contribute to the ability of S. aureus to invade the body?


Which of the following is an example of an exotoxin?


Lipid A is a(n) (cytotoxin/endotoxin/exotoxin) that stimulates the body to release chemicals that cause fever, inflammation, diarrhea, hemorrhaging, shock, and blood coagulation.


A syndrome is a group of symptoms and signs that collectively characterize a particular disease.


Two children attend the same daycare, but one child is at daycare in the morning and the other child attends the daycare facility in the afternoon. Both children become ill with fifth disease within a day of each other. How might the pathogen have infected both children?

fomite transmission

In the wake of the cyclone that hit Myanmar (Southeast Asia) in 2008, there were widespread reports of typhoid fever. Which of the following was the most likely mode of transmission?

contaminated water

The bacterium that causes tuberculosis can be expelled from the lungs by a cough and remain viable in the air for an hour or more. If a person inhales the bacteria from the air, what type of transmission has occurred?


A person is exposed to desert air containing fungus spores and develops valley fever as a result. Valley fever is an example of a ________ disease.


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