Micro Exam 2 Questions

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

5

The template strand of a gene reads: 3' ATGCGTAGGACTAAG 5' What is the sequence of the RNA transcribed from this gene? 5' TACGCATCCTGATTC 3' 5' CUUAGUCCUACGCAU 3' 5' UACGCAUCCUGAUUC 3' 5' AUGCGUAGGACUAAG 3'

5' UACGCAUCCUGAUUC 3'

Lysogenic viral DNA which has integrated into the host genome is referred to as induction. lytic. a prophage. lysogeny.

A prophage

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. Ability to mate with an F- cell Ability to synthesize sex pili Presence of a fertility factor

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

Which of the following are natural microbial components/pathways that scientists now use as tools in genetic engineering and biotechnology? Temperature stable DNA polymerase from thermophiles (ex. Taq) CRISPR/Cas Restriction Enzymes Plasmids Phage or virus transduction All of the above

All of the above

What is the key difference between donor cells and recipient cells? Size A chromosome Cell membranes An F plasmid

An F plasmid

In which stage does formation of mature viruses occur? Assembly Attachment Release Penetration Biosynthesis

Assembly

The host DNA is usually degraded during which stage? Biosynthesis Assembly Attachment Release Penetration

Biosynthesis

Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? The transferred genes typically recombine with the recipient chromosome. The cell membranes between the two strands never fuse together. Conjugation is typically disrupted before the fertility factor can be transferred. Hfr strains lack fertility factor.

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

Which of the following is a human disease caused by prions? shingles subacute sclerosing panencephalitis (SSPE) chickenpox (varicella) Creutzfeldt-Jakob disease (CJD)

Creutzfeldt-Jakob disease (CJD)

Which of the following is NOT utilized to culture viruses? bacterial cultures culture media embryonated eggs animal cell cultures laboratory animals

Culture media

Generalized transduction occurs when a bacteriophage inadvertently packages the wrong material into one of its newly-formed protein coats. While the source of this material may vary, it is always: tRNA. miRNA. mRNA. protein. DNA.

DNA

Which of the following is most likely a product of an early gene? spike proteins envelope proteins lysozyme DNA polymerase capsid proteins

DNA polymerase

Which of the following is true concerning a lysogenic viral replication cycle? Lysogenic infections are similar to persistent infections in that virus is constantly produced. Once the lysogenic portion of the cycle has begun, virus is never produced again. During lysogeny, the viral DNA is present as a circular plasmid. During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

Which of the following events might trigger induction of a temperate bacteriophage? An infected cell entering the logarithmic phase of growth Exposure to UV light Bacterial conjugation Normal cell division of an infected cell

Exposure to UV light

Place the steps of F plasmid transfer in the correct order. Single strand of F plasmid is transferred to the recipient cell. One strand of the F plasmid is cut at the origin of transfer. Complement transferred strand is synthesized. F pilus makes contact with the recipient cell.

F pilus makes contact with the recipient cell. One strand of the F plasmid is cut at the origin of transfer. Single strand of F plasmid is transferred to the recipient cell. Complement transferred strand is synthesized.

What is required by an F- cell to become an F+ cell? F plasmid Conjugation pilus An F- cell to be a recipient F+ chromosome

F plasmid

T/F Cell-to-cell contact is required for transduction to occur.

False

T/F Glycoprotein spikes are found on the capsids of all viruses.

False

T/F Transposition (insertion of a transposon into a DNA sequence) results in the formation of base substitution mutations in a cell's DNA

False

Each of the following can be used for the detection and/or identification of viruses except serologic (immunologic) tests observation of cytopathic effects polymerase chain reaction fermentation tests

Fermentation tests

A base insertion or deletion in the translated region of the gene may lead to Silent mutation Frameshift mutation Missense mutation Nonsense mutation

Frameshift mutation

How is generalized transduction different from specialized transduction? Only one specific host gene is transferred in both specialized transduction and generalized transduction. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage.

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

Frederick Griffith did experiments on genetic transformation. Which of the following statements about his experiments is accurate? The combination of living non-encapsulated bacteria and heat-killed encapsulated bacteria did not cause disease. Griffith used only pathogenic bacteria in his experiments. Griffith used bacteria in which the non-pathogenic strain was encapsulated but the pathogenic strain was not. Griffith found that hereditary material released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent.

Griffith found that hereditary material released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent.

How does an F+ cell differ from an Hfr cell? Hfr strains can no longer reproduce. Hfr cells cannot perform conjugation. Hfr strains have the F plasmid integrated into the chromosome. F+ cells have no plasmids.

Hfr strains have the F plasmid integrated into the chromosome.

How would you be able to determine if the Tn5 transposon you put into a bacterium integrated into the host genome? The cells would grow at a faster rate than without the transposon. The cells would become longer due to the extra DNA in them. If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin. If the Tn5 transposon integrated into the host genome, the cells would not be able to take in any new tranposons.

If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin.

Which operons are never transcribed unless activated? Inducible operons Repressible operons Inducible and repressible operons

Inducible operons

Which of the following is needed for a transposon to "jump" to a new location in the genome? Insertion sequence Antibiotic resistance gene F plasmid Origin of Transfer

Insertion sequence

What benefit does the F- strain receive from mating with an Hfr strain? It can now produce sex pili. It acquires new, potentially beneficial genes from the Hfr strain. It becomes an F+ cell. It picks up a fertility factor.

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

Which of the following statements regarding a bacterium that is R+ is FALSE? It is resistant to certain drugs and heavy metals. It is F+. R+ can be transferred to a different species. R+ can be transferred to a cell of the same species. It possesses a plasmid.

It is F+

What is the fate of the prophage during the lysogenic stage? It is degraded by the activity of host defense enzymes. It is copied every time the host DNA replicates. It is packaged into viral proteins and maintained until the host is exposed to an environmental stress. It is released from the cell by lysing the cell.

It is copied every time the host DNA replicates.

Why does a complex transposon often contain an extra piece of DNA between the two insertion elements? The insertion elements require a certain distance between them to function properly. It is often a gene that confers a survival advantage to the host, such as antibiotic resistance. It prevents degradation of the whole transposon.

It is often a gene that confers a survival advantage to the host, such as antibiotic resistance.

What is the function of the conjugation pilus? It converts F- cells into F+ cells. It contains an F plasmid. It pulls the F+ and F- cells together. It carries the chromosome of F- cells.

It pulls the F+ and F- cells together.

Which of the following statements regarding latent viral infections is true? During latent infections, small amounts of virus are produced, and virus numbers build up over time. Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form. Latent viral infections are almost always fatal. Latent infections can persist for years in an individual without causing any symptoms.

Latent infections can persist for years in an individual without causing any symptoms.

Which of the following repair mechanism(s) does not involve DNA polymerase? Light-repair mechanism Excision-repair mechanism Mismatch-repair mechanism

Light-repair mechanism

Which of the following repair enzymes cannot repair thymine dimers? Light-repair enzymes Excision-repair enzymes Mismatch-repair enzymes

Mismatch-repair enzymes

Which of the following gene mutations could disrupt or change the encoded protein's function? (Select all that apply) Missense Frameshift Silent Transposon

Missense, frameshift, and transposon

Which of the following statements about antibiotics are TRUE (select all that apply). Most of our antibiotics are produced by a few species of molds and bacteria. Antibiotic resistance means a patient no longer responds to an antibiotic drug. Antibiotics are useful for treating colds and the flu. To reduce resistance it's best to stop taking antibiotics once you feel better. Human misuse of antibiotics spreads resistance because it provides selective pressure. Only people who use antibiotic drugs regularly are at risk for antibiotic resistance. Consuming meat from antibiotic-treated animals will prevent food poisoning.

Most of our antibiotics are produced by a few species of molds and bacteria. Human misuse of antibiotics spreads resistance because it provides selective pressure.

Which of the following is NOT a way in which mutagens increase a cell's mutation rate? Mutagens damage DNA bases causing subsequent errors in DNA replication. Mutagens break the DNA helix inhibiting blocking DNA replication. Mutagens resemble DNA nucleotides and may be used when synthesizing new DNA. Mutagens replicate DNA incorrectly by mismatching bases. Mutagens are inserted between DNA base pairs, distorting the helix.

Mutagens replicate DNA incorrectly by mismatching bases.

A base substitution that changes a codon coding for an amino acid to a stop codon is called a Frameshift mutation Missense mutation Silent mutation Nonsense mutation

Nonsense mutation

Which of the following statements concerning prion diseases is true? Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc). Prion diseases affect humans but not other animals. Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues. Prion diseases are always inherited.

Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).

What cellular macromolecule is the fertility factor comprised of? Lipid Carbohydrate Nucleic acid Protein

Nucleic Acid

Which of the following types of macromolecules are found in all viruses? Select all that apply. Nucleic acids Polysaccharides Proteins Lipids

Nucleic acids and proteins

Which of the following is TRUE of chromosomal conjugation in E. coli? Select ALL that apply. The recipient cells will become F+. The recipient cell will become an Hfr donor. Only part of the chromosome is transferred. The transferred DNA needs to be recombined into the existing recipient chromosome for it to be replicated. The donor cell dies because it has lost its chromosome.

Only part of the chromosome is transferred. The transferred DNA needs to be recombined into the existing recipient chromosome for it to be replicated.

In which stage is the viral DNA introduced into the cell? Assembly Release Attachment Biosynthesis Penetration

Penetration

After T4 lytic phage attaches to an E. coli cell, which of the following occurs? Endocytosis Phage tail fibers pierce the bacterial cell wall so the nucleocapsid can enter T4 phage transfers DNA through the phage's F pilus Phage encoded lysozyme degrades the bacterial cell wall

Phage encoded lysozyme degrades the bacterial cell wall

How does the number of infectious prions increase? Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion. Prions reproduce by mitosis. Prions reproduce by binary fission. Prions form multimers which can then form more single copies of the prion protein.

Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.

Sigma Factors recognize origin of replication Start codons RNA transcripts promoters

Promoters

Most RNA viruses carry which of the following enzymes? lysozyme ATP synthase reverse transcriptase DNA-dependent DNA polymerase RNA-dependent RNA polymerase

RNA-dependent RNA polymerase

An envelope is acquired during which of the following steps? biosynthesis release penetration adsorption uncoating

Release

Which operons are always transcribed unless deactivated? Inducible operons Repressible operons Inducible and repressible operons

Repressible operons

Which statement is CORRECT concerning animal viruses? Enveloped viruses are surrounded by a lipid and carbohydrate coat, which is made from the host cell's mitochondria. Capsid proteins are produced in the nucleus. Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA. The genome of animal viruses is always single-stranded.

Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.

Which of the following are the main causative agents of the common cold? Streptococcus pneumoniae and Haemophilus influenzae Coronaviruses and Streptococcus pneumoniae Rhinoviruses and coronaviruses Rhinoviruses and Streptococcus pneumoniae

Rhinoviruses and coronaviruses

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. R strain cells fail to produce a capsule. S strain cells kill the mice. S strains are able to escape phagocytosis.

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

A mutation that affects the genotype of the organism but not the phenotype is called a Nonsense mutation Frameshift mutation Silent mutation Missense mutation

Silent mutation

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. The S strain was revived by the presence of the host's immune system. The R strain cells picked up the capsules from the S strain cells. The S strain fused with the R strain, making it resistant.

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

What characteristic of the S strain allows it to evade the immune system of the mice? They are naturally competent. The cells have a capsule. They are genetically engineered to be resistant to killing. They are resistant to heat.

The cells have a capsule.

What would happen if the only promoter sequence of a gene was deleted? Replication of the gene by DNA polymerase would not occur. The correct reading frame for the protein may not be established. The encoded protein would not be produced. Transcription of that gene would not occur, but ribosomes would translate the gene.

The encoded protein would not be produced.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? The DNA is chewed up by enzymes found in the recipient cell. The host DNA integrates, with the prophage, into the new recipient chromosome. The DNA begins to replicate without integrating into the host chromosome.

The host DNA integrates, with the prophage, into the new recipient chromosome.

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell? The viral DNA may integrate into the host genome during the lytic stage. The host cell is allowed to live during the lytic stage. The host cell dies during the lytic stage. The host cell can only divide during the lytic stage.

The host cell dies during the lytic stage.

Why is light required for photolysases? The light provides the energy to break the bonds between the thymine dimers. Light is used to activate the DNA polymerase to repair the gap. The light helps identify the damaged strands. Light excises the section of DNA to be repaired.

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

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. Methyl groups are required to cut DNA. Methyl groups activate photolysases in light-repair. Methyl groups identify thymine dimers in the DNA.

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

Why are the beta-pleated multimers of PrP potentially pathogenic? They are not detected by other organisms. The multimers are more stable and resistant to protease. They are found on the surface of immune cells, resulting in damage to the immune system. They repress the immune system.

The multimers are more stable and resistant to protease.

Where on the DNA strand does a repressor bind? The operator The promoter The structural genes The inducer

The operator

How does specialized transduction differ from regular lysogeny? The prophage is not excised during specialized transduction. The resulting bacteriophage from specialized transduction does not contain any viral DNA. The resulting bacteriophage from specialized transduction cannot infect a new host cell. The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. The phage causes the destruction of any antibiotic present during the specialized transduction process. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

Which of the following genetic elements is transcribed into a single mRNA? The promoter The operator The structural genes The inducer The repressor

The structural genes

A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient? The virus is infecting cells and then releasing only small amounts of virus. The virus is incorporating its nucleic acid with that of the patient's cells. The virus is causing the death of the infected cells in the patient. The virus is not killing any cells in the host. The virus is slowly killing the patient's cells.

The virus is causing the death of the infected cells in the patient.

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? The virus would infect new hosts. The cell could still be revived by the virus. The virus would not be able to infect new hosts.

The virus would not be able to infect new hosts.

How is a complex transposon different from a simple transposon? Complex transposons have one very long insertion sequence. They always integrate in multiple copies into the host genome. Complex transposons code for different types of transposase. They have two simple transposons with another DNA sequence between them.

They have two simple transposons with another DNA sequence between them.

What is unique about transduction compared to normal bacteriophage infection? Transduction transfers DNA from the chromosome of one cell to another. The bacteriophage does not erupt from an infected cell during transduction. The bacteriophage takes fragments of the cell with it during transduction.

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

T/F Both base substitution and frameshift mutations can result in the formation of premature stop codons.

True

T/F Dogs do not get measles because their cells lack the correct receptor sites for that virus.

True

T/F In the Ames test, any colonies that form on the control should be the result of spontaneous mutations.

True

T/F Most drugs that interfere with viral multiplication also interfere with host cell function.

True

T/F Mutations that are harmful to cells occur more frequently than those that benefit cells.

True

T/F Positive sense RNA strands of viruses are treated like mRNA inside the host cell.

True

T/F Recombination will always alter a cell's genotype.

True

Which of the following statements best describes why antibiotics are ineffective treatments for the common cold? Viruses contain drug pumps that pump antibiotic out of the virus before the antibiotic can reach its target. Viruses contain enzymes that deactivate antibiotics before they can reach their targets. Viruses are constantly mutating and changing their antibiotic targets. Viruses do not possess targets for antibiotics.

Viruses do not possess targets for antibiotics.

Competent cells are cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. are killed by heat. are also considered "rough-strain" based on colony phenotype. have the ability to produce capsules.

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

A transducing phage contains fragments of the host chromosome instead of the viral genome. cannot infect new host cells. has a viral coat made of host proteins. is a lysogenic bacteriophage.

contains fragments of the host chromosome instead of the viral genome.

Generalized transduction involves bacteriophages that can randomly integrate into the host genome digest (or fragment) the host genome transfer F plasmids package naked DNA from the environment

digest (or fragment) the host genome

Lysogeny can result in all of the following EXCEPT phage conversion. immunity to reinfection by the same phage. immunity to reinfection by any phage. acquisition of new characteristics by the host cell. specialized transduction.

immunity to reinfection by any phage.

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves replication of viral nucleic acid. lysis of the host cell. injection of naked nucleic acid into the host cell. assembly of viral components. adsorption to specific receptors.

injection of naked nucleic acid into the host cell.

In order to test if a chemical is a mutagen, you need to measure changes in the rate of DNA replication levels of reactive oxygen species (ROS) and DNA breaks cancer rates within a population its effect on mutation rate

its effect on mutation rate

A simple way to determine if gene mutations have occurred (changes in the genotype) is to observe a changes in a correlated phenotype treat the cells with radiation look at the DNA under a microscope make more mutations

observe a changes in a correlated phenotype

A virus's ability to infect an animal cell depends primarily upon the enzymatic activity of a host cell. type of viral nucleic acid. host cell's ability to phagocytize viral particles. presence of receptor sites on the cell membrane. presence of pili on the host cell wall.

presence of receptor sites on the cell membrane.

Which type of HGT must involve a temperate phage? conjugation (chromosomal transfer) tranformation generalized transduction specialized transduction

specialized transduction

Mice that are injected with only the R strain of Streptococcus pneumoniae stay healthy, because their immune systems can kill this strain easily. are killed, because R strain cells are deadly. become sick for prolonged periods of time.

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

When a transducing phage interacts with a new host cell, the new host cell will be lysed. it will cause the new cell to produce more transducing phage. the DNA from the previous host can recombine with the new host chromosome.

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

Retroviridae ("Retroviruses") are reverse transcribing viruses, therefore ___. infect the human nervous system use RNA as a template for DNA synthesis cause latent infections use a host polymerase for genome replication evolved in the 1960s

use RNA as a template for DNA synthesis