Biology 111 Exam 4 Test Bank

The reason for using Taq polymerase for PCR is that _____. A) it is heat stable and can withstand the heating step of PCR B) only minute amounts are needed for each cycle of PCR C) it binds more readily than other polymerases to the primers D) it has regions that are complementary to the primers

A) it is heat stable and can withstand the heating step of PCR

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator? A) inducer B) promoter C) repressor D) corepressor

A) inducer

The product of the p53 gene _____. A) inhibits the cell cycle B) slows down the rate of DNA replication by interfering with the binding of DNA polymerase C) causes cells to reduce expression of genes involved in DNA repair D) allows cells to pass on mutations due to DNA damage

A) inhibits the cell cycle

Effective antiviral drugs are usually associated with which of the following properties? A) interference with viral replication B) prevention of the host from becoming infected C) removal of viral proteins D) removal of viral mRNAs

A) interference with viral replication

A primary transcript in the nucleus of a eukaryotic cell is _____ the functional mRNA, while a primary transcript in a prokaryotic cell is _____ the functional mRNA. A) the same size as; smaller than B) larger than; the same size as C) larger than; smaller than D) the same size as; larger than

B) larger than; the same size as

Viruses _____. A) manufacture their own ATP, proteins, and nucleic acids B) use the host cell to copy themselves and make viral proteins C) use the host cell to copy themselves and then viruses synthesize their own proteins D) metabolize food and produce their own ATP

B) use the host cell to copy themselves and make viral proteins

The trp repressor blocks transcription of the trp operon when the repressor _____. A) binds to the inducer B) binds to tryptophan C) is not bound to tryptophan D) is not bound to the operator

B) binds to tryptophan

Which of the following problems with animal cloning might result in premature death of the clones? A) use of pluripotent instead of totipotent stem cells B) use of nuclear DNA as well as mtDNA C) abnormal gene regulation due to variant methylation D) the indefinite replication of totipotent stem cells

C) abnormal gene regulation due to variant methylation

Which viruses have single-stranded RNA that acts as a template for DNA synthesis? A) proviruses B) viroids C) bacteriophages D) retroviruses

D) retroviruses

Which of the following is required to make complementary DNA (cDNA) from RNA? A) restriction enzymes (endonucleases) B) gene cloning C) DNA ligase D) reverse transcriptase

D) reverse transcriptase

Which of the following is the first event to take place in translation in eukaryotes? A) base pairing of activated methionine-tRNA to AUG of the messenger RNA B) binding of the larger ribosomal subunit to smaller ribosomal subunits C) covalent bonding between the first two amino acids D) the small subunit of the ribosome recognizes and attaches to the cap of mRNA

D) the small subunit of the ribosome recognizes and attaches to the cap of mRNA

Put the following events of elongation in prokaryotic translation in chronological order. 1. Binding of mRNA with small ribosomal subunit 2. Recognition of initiation codon 3. Complementary base pairing between initiator codon and anticodon of initiator tRNA 4. Base pairing of the mRNA codon following the initiator codon with its complementary tRNA 5. Attachment of the large subunit

1, 2, 3, 5, 4

Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide. 1. insertion mutation deep within an intron 2. substitution mutation at the third position of an exonic codon 3. substitution mutation at the second position of an exonic codon 4. deletion mutation within the first exon of the gene

4, 3, 2, 1

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is _____. A) 3`UCA 5` B) 3`UGA 5` C) 5`TCA 3` D) 3`ACU 5`

A) 3`UCA 5`

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following? A) A gene from an organism can theoretically be expressed by any other organism. B) DNA was the first genetic material. C) The same codons in different organisms translate into different amino acids. D) Different organisms have different types of amino acids

A) A gene from an organism can theoretically be expressed by any other organism.

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). To make this conversion, what has been done to the adult cells? A) A retrovirus is used to introduce four specific regulatory genes. B) The adult stem cells must be fused with embryonic cells. C) Cytoplasm from embryonic cells is injected into the adult cells. D) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.

A) A retrovirus is used to introduce four specific regulatory genes.

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures? A) Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory. B) Genetically modified organisms are not allowed to be part of our food supply. C) Transgenic plants are engineered so that the plant genes cannot hybridize. D) Experiments involving HIV or other potentially dangerous viruses have been banned.

A) Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.

Which of the following processes within viral replication is the greatest source of genetic variation in RNA virus populations? A) High mutation rate due to lack of proofreading of RNA genome replication errors. B) Transcription from the host cell RNA polymerase introduces numerous mutations. C) Capsid proteins from the host cell can replace the viral capsid. D) Viral RNA is translated by host cell ribosomes

A) High mutation rate due to lack of proofreading of RNA genome replication errors

Will treating a viral infection with antibiotics affect the course of the infection? A) No; antibiotics work by inhibiting enzymes specific to bacteria. Antibiotics have no effect on eukaryotic or virally encoded enzymes. B) No; antibiotics do not kill viruses because viruses do not have DNA or RNA. C) Yes; antibiotics activate the immune system, and this decreases the severity of the infection. D) Yes; antibiotics can prevent viral entry into the cell by binding to host-receptor proteins

A) No; antibiotics work by inhibiting enzymes specific to bacteria. Antibiotics have no effect on eukaryotic or virally encoded enzymes

Which of the following best describes the significance of the TATA box in eukaryotic promoters? A) It is the recognition site for a specific transcription factor. B) It sets the reading frame of the mRNA. C) It is the recognition site for ribosomal binding. D) Its significance has not yet been determined.

A) It is the recognition site for a specific transcription factor.

What is the function of reverse transcriptase in retroviruses? A) It uses viral RNA as a template for DNA synthesis. B) It converts host cell RNA into viral DNA. C) It translates viral RNA into proteins. D) It uses viral RNA as a template for making complementary RNA strands.

A) It uses viral RNA as a template for DNA synthesis.

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene, and why? A) Only a single amino acid could change, because the reading frame is unaffected. B) The amino acid sequence would be substantially altered, because the reading frame would change with a single base substitution. C) All amino acids following the substitution would be affected, because the reading frame would be shifted. D) It is not possible for a single base substitution to affect protein structure, because each codon is three bases long

A) Only a single amino acid could change, because the reading frame is unaffected

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called _____. A) RNA interference B) RNA obstruction C) RNA blocking D) RNA disposal

A) RNA interference

What information is critical to the success of polymerase chain reaction (PCR) itself? A) The DNA sequence of the ends of the DNA to be amplified must be known. B) The complete DNA sequence of the DNA to be amplified must be known. C) The sequence of restriction-enzyme recognition sites in the DNA to be amplified must be known. D) The sequence of restriction-enzyme recognition sites in the DNA to be amplified and in the plasmid where the amplified DNA fragment will be cloned must be known.

A) The DNA sequence of the ends of the DNA to be amplified must be known.

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding? A) The cells from the two sources exhibit different patterns of DNA methylation. B) Adult stem cells have more DNA nucleotides than their counterparts. C) The two kinds of cells have virtually identical gene expression patterns in microarrays. D) The nonstem cells have fewer repressed genes

A) The cells from the two sources exhibit different patterns of DNA methylation.

According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon? A) The lac operon would be transcribed continuously. B) Only lacZ would be transcribed. C) Only lacY would be transcribed. D) Galactosidase permease would be produced, but would be incapable of transporting lactose.

A) The lac operon would be transcribed continuously

What characteristic of short tandem repeats (STRs) DNA makes it useful for DNA fingerprinting? A) The number of repeats varies widely from person to person or animal to animal. B) The sequence of DNA that is repeated varies significantly from individual to individual. C) The sequence variation is acted upon differently by natural selection in different environments. D) Every racial and ethnic group has inherited different short tandem repeats.

A) The number of repeats varies widely from person to person or animal to animal.

If a viral host cell has a mutation that interferes with the addition of carbohydrates to proteins in the Golgi, which of the following could likely result? A) The viral envelope proteins would not be glycosylated and might not arrive at the host plasma membrane. B) The viral capsid proteins would not be glycosylated and might not arrive at the host plasma membrane. C) The viral core proteins would not be glycosylated and might not arrive at the host plasma membrane. D) The virus would be unable to reproduce within the host cell.

A) The viral envelope proteins would not be glycosylated and might not arrive at the host plasma membrane.

Which of the following supports the argument that viruses are nonliving? A) They are not cellular. B) Their DNA does not encode proteins. C) They have RNA rather than DNA. D) They do not evolve

A) They are not cellular

Which of the following DNA mutations is most likely to damage the protein it specifies? A) a base-pair deletion B) an addition of three nucleotides C) a substitution in the last base of a codon D) a codon deletion

A) a base-pair deletion

Which of the following is most likely to have a small protein called ubiquitin attached to it? A) a cyclin protein, that usually acts in G1, in a cell that is in G2 B) a cell surface protein that requires transport from the ER C) an mRNA leaving the nucleus to be translated D) an mRNA produced by an egg cell that will be retained until after fertilization

A) a cyclin protein, that usually acts in G1, in a cell that is in G2

Which of the following best describes siRNA? A) a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA B) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns C) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor D) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits

A) a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

Bacterial cells protect their own DNA from restriction enzymes (endonucleases) by _____. A) adding methyl groups to adenines and cytosines B) using DNA ligase to seal the bacterial DNA into a closed circle C) adding histones to protect the double-stranded DNA D) forming "sticky ends" of bacterial DNA to prevent the enzyme (endonuclease) from attaching

A) adding methyl groups to adenines and cytosines

The protein of the bicoid gene in Drosophila determines the _____ of the embryo. A) anterior-posterior axis B) anterior-lateral axis C) posterior-dorsal axis D) posterior-ventral axis

A) anterior-posterior axis

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation? A) inducer B) promoter C) transcription factor D) cAMP

A) inducer

In eukaryotes, general transcription factors _____ A) bind to other proteins or to the TATA box B) inhibit RNA polymerase binding to the promoter and begin transcribing C) usually lead to a high level of transcription even without additional specific transcription factors D) bind to sequences just after the start site of transcription

A) bind to other proteins or to the TATA box

The release factor (RF) _____. A) binds to the stop codon in the A site in place of a tRNA B) releases the amino acid from its tRNA to allow the amino acid to form a peptide bond C) supplies a source of energy for termination of translation D) releases the ribosome from the ER to allow polypeptides into the cytosol

A) binds to the stop codon in the A site in place of a tRNA

Transgenic mice are useful to human researchers because they _____. A) can be valuable animal models of human disease B) are essential for mapping human genes C) are now used in place of bacteria for cloning human genes D) were instrumental in pinpointing the location of the huntingtin gene

A) can be valuable animal models of human disease

A person is most likely to recover from a viral infection if the infected cells _____. A) can undergo normal cell division B) can carry on translation, at least for a few hours C) produce and release viral protein D) transcribe viral mRNA

A) can undergo normal cell division

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer? A) colorectal only B) lung and breast C) lung only D) lung and prostate

A) colorectal only

Imagine that you compare two DNA sequences found in the same location on homologous chromosomes. On one of the homologs, the sequence is AACTACGA. On the other homolog, the sequence is AACTTCGA. Within a population, you discover that each of these sequences is common. These sequences _____. A) contain an SNP that may be useful for genetic mapping B) identify a protein-coding region of a gene C) cause disease D) do none of the listed actions

A) contain an SNP that may be useful for genetic mapping

A mutation that inactivates a regulatory gene of a repressible operon in an E. coli cell would result in _____. A) continuous transcription of the structural gene controlled by that regulator B) complete inhibition of transcription of the structural gene controlled by that regulator C) irreversible binding of the repressor to the operator D) continuous translation of the mRNA because of alteration of its structure

A) continuous transcription of the structural gene controlled by that regulator

The fact that plants can be cloned from somatic cells demonstrates that _____. A) differentiated cells retain all the genes of the zygote B) genes are lost during differentiation C) the differentiated state is normally very unstable D) differentiation does not occur in plants

A) differentiated cells retain all the genes of the zygote

To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would most likely be successful with which of the following methods? A) electroporation followed by recombination B) introducing a plasmid into the cell C) infecting the mouse cell with a Ti plasmid D) transcription and translation

A) electroporation followed by recombination

One possible use of transgenic plants is in the production of human proteins, such as vaccines. Which of the following is a possible hindrance that must be overcome? A) prevention of transmission of plant allergens to the vaccine recipients B) prevention of vaccine-containing plants being consumed by insects C) use of plant cells to translate non-plant-derived mRNA D) inability of the human digestive system to accept plant-derived protein

A) prevention of transmission of plant allergens to the vaccine recipients

A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted the mutated gene into a cell. To have the mutated sequence disable the function of the gene, what must then occur? A) recombination resulting in replacement of the wild type with the mutated gene B) use of a microarray to verify continued expression of the original gene C) replication of the cloned gene using a bacterial plasmid D) transcription of the cloned gene using a BAC

A) recombination resulting in replacement of the wild type with the mutated gene

Which of the following could use reverse transcriptase to transcribe its genome? A) ssRNA B) dsRNA C) ssDNA D) dsDNA

A) ssRNA

A population of viruses with similar characteristics is called a _____. A) strain B) species C) type D) genome

A) strain

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because _____. A) their normal products participate in repair of DNA damage B) the mutant forms of either one of these prevent breast cancer C) the normal genes make estrogen receptors D) they block penetration of breast cells by chemical carcinogens

A) their normal products participate in repair of DNA damage

) RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibit its translation. For which of the following might this technique be useful? A) to decrease the production from a harmful mutated gene B) to destroy an unwanted allele in a homozygous individual C) to form a knockout organism that will not pass the deleted sequence to its progeny D) to raise the concentration of a desired protein

A) to decrease the production from a harmful mutated gene

Once a peptide has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next? A) translocation B) reading of the next codon of mRNA C) initiation D) The codon-anticodon hydrogen bonds holding the tRNA in the A site are broken.

A) translocation

The difference between vertical and horizontal transmission of plant viruses is that vertical transmission is _____. A) transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant B) the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level C) the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size D) the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species

A) transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant

Which of the following is a protein produced by a regulatory gene? A) operon B) inducer C) promoter D) repressor

D) repressor

Why is it so important to be able to amplify DNA fragments when studying genes? A) Before amplification, DNA fragments are likely to bind to RNA and no longer be able to be analyzed. B) A gene may represent only a millionth of the cell's DNA. C) Restriction enzymes (endonucleases) cut DNA into fragments that are too small. D) A clone requires multiple copies of each gene per clone.

B) A gene may represent only a millionth of the cell's DNA.

How does termination of translation take place? A) The end of the mRNA molecule is reached. B) A stop codon is reached. C) The cap is reached. D) The poly-A tail is reached

B) A stop codon is reached.

Which of the following sequences is most likely to be cut by a restriction enzyme? A) AATTCT TTAAGA B) AATATT TTATAA C) AAAATT TTTTAA D) ACTACT TGATGA

B) AATATT TTATAA

Which of the following human diseases is caused by a virus that requires reverse transcriptase to transcribe its genome inside the host cell? A) herpes B) AIDS C) smallpox D) influenza

B) AIDS

What is difference between an epidemic and a pandemic? A) An epidemic is a disease; a pandemic is a treatment. B) An epidemic is restricted to a local region; a pandemic is global. C) An epidemic has low mortality; a pandemic has higher mortality. D) An epidemic is caused by a bacterial infection; a pandemic is caused by a viral infection.

B) An epidemic is restricted to a local region; a pandemic is global.

When the Bicoid protein is expressed in Drosophila, the embryo is still syncytial (divisions between cells are not yet fully developed). This information helps to explain which observation by Nüsslein-Volhard and Wieschaus? A) mRNA from the egg is translated into the Bicoid protein. B) Bicoid protein diffuses throughout the embryo in a concentration gradient. C) Bicoid protein serves as a transcription regulator. D) Bicoid protein determines the dorsoventral axis of the embryo.

B) Bicoid protein diffuses throughout the embryo in a concentration gradient.

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation? A) The use of adult stem cells is likely to produce more cell types than the use of embryonic stem cells. B) Cloning to produce embryonic stem cells may lead to great medical benefits for many. C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning. D) A clone that lives until the blastocyst stage does not yet have human DNA.

B) Cloning to produce embryonic stem cells may lead to great medical benefits for many.

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes (endonucleases). III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA. A) II, III, V, IV, I B) III, II, IV, V, I C) III, IV, V, I, II D) IV, V, I, II, III

B) III, II, IV, V, I

What must occur before a newly made polypeptide is secreted from a cell? A) It must be translated by a ribosome that remains free within the cytosol. B) Its signal sequence must target it to the ER, after which it goes to the Golgi. C) Its signal sequence must be cleaved off before the polypeptide can enter the ER. D) Its signal sequence must target it to the plasma membrane, where it causes exocytosis.

B) Its signal sequence must target it to the ER, after which it goes to the Golgi.

Once researchers identified DNA as the unit of inheritance, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. What is the mechanism of information transfer in eukarotes? A) DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis. B) Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place. C) Proteins transfer information from the nucleus to the ribosome, where protein synthesis takes place. D) Transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place

B) Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.

In the process of transcription, _____. A) DNA is replicated B) RNA is synthesized C) proteins are synthesized D) mRNA attaches to ribosomes

B) RNA is synthesized

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein? A) RNA polymerase I B) RNA polymerase II C) RNA polymerase III D) primase

B) RNA polymerase II

Which of the following statements best describes the termination of transcription in prokaryotes? A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase. B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. C) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome. D) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Why do RNA viruses appear to have higher rates of mutation? A) RNA nucleotides are more unstable than DNA nucleotides. B) Replication of their genomes does not involve proofreading. C) RNA viruses can incorporate a variety of nonstandard bases. D) RNA viruses are more sensitive to mutagens

B) Replication of their genomes does not involve proofreading

Which one of the following statements about RNA processing is true? A) Exons are cut out before mRNA leaves the nucleus. B) Ribozymes may function in RNA splicing. C) RNA splicing can be catalyzed by tRNA. D) A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus.

B) Ribozymes may function in RNA splicing.

In large scale, genome-wide association studies in humans we look for _____. A) lengthy sequences that might be shared by most members of a population B) SNPs where one allele is found more often in persons with a particular disorder than in healthy controls C) SNPs where one allele is found in families with particular introns sequence D) SNPs where one allele is found in two or more adjacent genes

B) SNPs where one allele is found more often in persons with a particular disorder than in healthy controls

Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its 5` end, the RNA genome has a viral protein (VPg) instead of a 5` cap. This is followed by a nontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment? A) Host cell ribosomes only translate the viral code into short polypeptides. B) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones. C) The RNA is translated into short polypeptides, which are subsequently assembled into large ones. D) The large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the virus.

B) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.

HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings? A) HIV can be transmitted more easily from person to person than the flu virus B) The flu virus can be transmitted more easily from person to person than HIV C) This property of HIV makes it more likely to be a pandemic than the flu virus D) Disinfecting surfaces is more important to reduce the spread of HIV than the flu

B) The flu virus can be transmitted more easily from person to person than HIV

Which of the following mechanisms is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells? A) Environmental signals enter the cell and bind directly to promoters. B) The genes share a single common enhancer, which allows appropriate activators to turn on their transcription at the same time. C) The genes are organized into a large operon, allowing them to be coordinately controlled as a single unit. D) A single repressor is able to turn off several related genes.

B) The genes share a single common enhancer, which allows appropriate activators to turn on their transcription at the same time.

Which of the following is true of embryonic stem cells but not of adult stem cells? A) They normally differentiate into only eggs and sperm. B) They can give rise to all cell types in the organism. C) They can continue to reproduce for an indefinite period. D) One aim of using them is to provide cells for repair of diseased tissue.

B) They can give rise to all cell types in the organism.

A researcher introduces double-stranded RNA into a culture of mammalian cells and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe When she finds that the introduced strand separates into single-stranded RNAs, what other evidence of this single-stranded RNA piece's activity can she find? A) She can measure the degradation rate of the remaining single strand. B) The rate of accumulation of the polypeptide encoded by the target mRNA is reduced. C) The amount of miRNA is multiplied by its replication. D) The cell's translation ability is entirely shut down.

B) The rate of accumulation of the polypeptide encoded by the target mRNA is reduced.

Viruses use the host's machinery to make copies of themselves. However, some human viruses require a type of replication that humans do not normally have. For example, humans normally do not have the ability to convert RNA into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires? A) The virus causes mutations in the human cells, resulting in the formation of new enzymes that are capable of performing these roles. B) The viral genome codes for specialized enzymes not in the host. C) The virus infects only those cells and species that can perform all the replication roles necessary. D) Viruses can stay in a quiescent state until the host cell evolves this ability.

B) The viral genome codes for specialized enzymes not in the host.

Which of the following statements is true about protein synthesis in prokaryotes? A) Extensive RNA processing is required before prokaryotic transcripts can be translated. B) Translation can begin while transcription is still in progress. C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles. D) Unlike eukaryotes, prokaryotes require no initiation or elongation factors.

B) Translation can begin while transcription is still in progress.

Which of the following represents a difference between viruses and viroids? A) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells. B) Viruses have capsids composed of protein, whereas viroids have no capsids. C) Viruses have genomes composed of RNA, whereas viroids have genomes composed of DNA. D) Viruses cannot pass through plasmodesmata, whereas viroids can.

B) Viruses have capsids composed of protein, whereas viroids have no capsids

A single base substitution mutation is least likely to be deleterious when the base change results in _____. A) a stop codon B) a codon that specifies the same amino acid as the original codon C) an amino acid substitution that alters the tertiary structure of the protein D) an amino acid substitution at the active site of an enzyme

B) a codon that specifies the same amino acid as the original codon

In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP activity in stimulating transcription? A) an increase in glucose and an increase in cAMP B) a decrease in glucose and an increase in cAMP C) an increase in glucose and a decrease in cAMP D) a decrease in glucose and a decrease in the repressor

B) a decrease in glucose and an increase in cAMP

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) a deletion of a codon B) a deletion of two nucleotides C) a substitution of the third nucleotide in an ACC codon D) a substitution of the first nucleotide of a GGG codon

B) a deletion of two nucleotides

If a Drosophila female has a homozygous mutation for a maternal effect gene, _____. A) she will not develop past the early embryonic stage B) all of her offspring will show the mutant phenotype, regardless of their genotype C) only her male offspring will show the mutant phenotype D) only her female offspring will show the mutant phenotype

B) all of her offspring will show the mutant phenotype, regardless of their genotype

A ribozyme is _____. A) a catalyst that uses RNA as a substrate B) an RNA with catalytic activity C) an enzyme that catalyzes the association between the large and small ribosomal subunits D) an enzyme that synthesizes RNA as part of the transcription process

B) an RNA with catalytic activity

Which of the following viruses would most likely have reverse transcriptase? A) an RNA-based lytic virus B) an RNA-based lysogenic virus C) a DNA-based lytic virus D) a DNA-based lysogenic virus

B) an RNA-based lysogenic virus

A researcher introduces double-stranded RNA into a culture of mammalian cells and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe Some time later, she finds that the introduced strand separates into single-stranded RNAs, one of which is degraded. What does this enable the remaining strand to do? A) attach to histones in the chromatin B) bind to complementary regions of target mRNAs C) activate other siRNAs in the cell D) bind to noncomplementary RNA sequences

B) bind to complementary regions of target mRNAs

Alternative RNA splicing _____. A) is a mechanism for increasing the rate of translation B) can allow the production of proteins of different sizes and functions from a single mRNA C) can allow the production of similar proteins from different RNAs D) increases the rate of transcription

B) can allow the production of proteins of different sizes and functions from a single mRNA

Viral infections in plants _____. A) can be controlled with antibiotics B) can spread within a plant via plasmodesmata C) have little effect on plant growth D) are not spread by animals

B) can spread within a plant via plasmodesmata

Which of the following occurs in prokaryotes but not in eukaryotes? A) post-transcriptional splicing B) concurrent transcription and translation C) translation in the absence of a ribosome D) gene regulation

B) concurrent transcription and translation

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture In one set of experiments she succeeded in increasing acetlylation of histone tails. Which of the following results would she most likely see? A) increased chromatin condensation B) decreased chromatin condensation C) decreased binding of transcription factors D) inactivation of the selected genes

B) decreased chromatin condensation

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. We expect that the plants would _____. A) develop some but not all of the symptoms of the TMV infection B) develop the typical symptoms of TMV infection C) not show any disease symptoms D) become infected, but the sap from these plants would be unable to infect other plants

B) develop the typical symptoms of TMV infection

In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated? A) genes coding for enzymes that act in the colon B) genes involved in control of the cell cycle C) genes that are especially susceptible to mutation D) genes of the bacteria, which are abundant in the colon

B) genes involved in control of the cell cycle

Which of the following can be effective in preventing the onset of viral infection in humans? A) taking vitamins B) getting vaccinated C) taking antibiotics D) taking drugs that inhibit transcription

B) getting vaccinated

A virus consisting of a single strand of RNA, which is transcribed into complementary DNA, is a _____. A) protease B) retrovirus C) RNA replicase virus D) nonenveloped virus

B) retrovirus

Which of the following uses labeled probes to visualize the expression of genes in whole tissues and organisms? A) RT-PCR B) in situ hybridization C) DNA microarrays D) RNA interference

B) in situ hybridization

Genetically engineered plants _____. A) are more difficult to develop than genetically engineered animals B) include transgenic rice plants that can grow in water of high salinity C) are used in research but not yet in commercial agricultural production D) are banned throughout the world

B) include transgenic rice plants that can grow in water of high salinity

The herpes viruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can later reactivate, replicate again, and infect others. If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection? A) vaccinate of all persons with preexisting cases of HSV B) interfere with new viral replication in preexisting cases of HSV C) treat HSV lesions to shorten the breakout D) educate people about avoiding sources of infection

B) interfere with new viral replication in preexisting cases of HSV

Codons are part of the molecular structure of _____. A) a protein B) mRNA C) tRNA D) rRNA

B) mRNA

To make a vaccine against mumps, measles, or rabies, which type of viruses would be useful? A) dsDNA viruses B) negative-sense ssRNA viruses C) positive-sense ssRNA viruses D) dsRNA viruses

B) negative-sense ssRNA viruses

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and blocks expression of some transposons. These are known as _____. A) miRNA B) piRNA C) snRNA D) siRNA

B) piRNA

A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that _____. A) none of the proteins in the cell will contain phenylalanine B) proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU C) the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysinespecifying anticodons D) the ribosome will skip a codon every time a UUU is encountered

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

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using _____. A) a restriction enzyme (endonuclease) to cut the gene into shorter pieces B) reverse transcriptase to reconstruct the gene from its mRNA C) DNA polymerase to reconstruct the gene from its polypeptide product D) DNA ligase to put together fragments of the DNA that code for a particular polypeptide

B) reverse transcriptase to reconstruct the gene from its mRNA

Transcription of structural genes in an inducible operon _____. A) occurs continuously in the cell B) starts when the pathway's substrate is present C) starts when the pathway's product is present D) stops when the pathway's product is present

B) starts when the pathway's substrate is present

There are sixty-one mRNA codons that specify an amino acid, but only forty-five tRNAs. This is best explained by the fact that _____. A) some tRNAs have anticodons that recognize four or more different codons B) the rules for base pairing between the third base of a codon and tRNA are flexible C) many codons are never used, so the tRNAs that recognize them are dispensable D) the DNA codes for all sixty-one tRNAs, but some are then destroyed

B) the rules for base pairing between the third base of a codon and tRNA are flexible

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant? A) It cannot bind to the operator. B) It cannot make a functional repressor. C) It cannot bind to the inducer. D) It makes a repressor that binds CAP.

C) It cannot bind to the inducer.

Silencing of selected genes is often done using RNA interference (RNAi). Which of the following questions would NOT be answered with this process? A) What is the function of gene 432 in a particular species of annelid? B) What will happen in a particular insect's digestion if gene 173 is not able to be translated? C) Is gene HA292 expressed in individuals for a disorder in humans? D) Will the disabling of this gene in Drosophila and in a mouse cause similar results?

C) Is gene HA292 expressed in individuals for a disorder in humans?

Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression? A) mRNA, tRNA, and rRNA are transcribed. B) RNA polymerase binds to the promoter. C) A cap is added to the 5` end of the mRNA. D) RNA polymerase requires a primer to elongate the molecule.

C) A cap is added to the 5` end of the mRNA.

Which of the following is characteristic of the lytic cycle? A) Viral DNA is incorporated into the host genome. B) The viral genome replicates without destroying the host. C) A large number of phages are released at a time. D) The virus—host relationship usually lasts for generations

C) A large number of phages are released at a time.

During elongation, which site in the ribosome represents the location where a codon is being read? A) E site B) P site C) A site D) the small ribosomal subunit

C) A site

Which one of the following, if missing, would usually prevent translation from starting? A) exon B) cap C) AUG codon D) poly-A tail

C) AUG codon

The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur? A) The embryo would grow extra wings and legs. B) The embryo would probably show no anterior development and die. C) Anterior structures would form in both ends of the embryo. D) The embryo would develop normally

C) Anterior structures would form in both ends of the embryo.

For applications in gene therapy, what is the most favorable characteristic of retroviruses? A) Retroviruses have an RNA genome. B) Retroviruses possess reverse transcriptase. C) DNA copies of retroviral genomes become integrated into the genome of the infected cell. D) Retroviruses mutate often.

C) DNA copies of retroviral genomes become integrated into the genome of the infected cell.

What is the main structural difference between enveloped and nonenveloped viruses? A) Enveloped viruses have their genetic material enclosed by a layer made only of protein. B) Nonenveloped viruses have only a phospholipid membrane, while enveloped viruses have two membranes, the other one being a protein capsid. C) Enveloped viruses have a phospholipid membrane outside their capsid, whereas nonenveloped viruses do not have a phospholipid membrane. D) Both types of viruses have a capsid and phospholipid membrane; but in the nonenveloped virus the genetic material is between these two membranes, while in the enveloped virus the genetic material is inside both membranes

C) Enveloped viruses have a phospholipid membrane outside their capsid, whereas nonenveloped viruses do not have a phospholipid membrane.

One predicted aspect of climate change is that climates, including precipitation and temperature, over most of the Earth will become more variable. Which of the following is a good crop genetic engineering strategy if this is true? A) Only plant crops that are genetically engineered. B) Genetically engineer most crops to withstand very long droughts. C) Genetically engineer several genotypes within single crop types. D) Genetically engineer the fastest growing crops possible.

C) Genetically engineer several genotypes within single crop types.

Why do scientists consider HIV to be an emerging virus? A) HIV infected humans long before the 1980s, but it has now mutated to a more deadly form. B) HIV mutates rapidly making the virus very different from HIV in the early 1980s. C) HIV suddenly became apparent and widespread in the 1980s. D) HIV is now starting to cause diseases other than AIDS, such as rare types of cancers and pneumonias.

C) HIV suddenly became apparent and widespread in the 1980s.

You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal to analyze the substance and determine the nature of the infectious agent. I. Treat the substance with enzymes that destroy all nucleic acids and then determine whether the substance is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance on nutritive medium, away from any plant cells. IV. Treat the sample with proteases that digest all proteins and then determining whether the substance is still infectious. If you already know that the infectious agent was either bacterial or viral, which method(s) listed above would allow you to distinguish between these two possibilities? A) I B) II C) II or III D) IV

C) II or III

DNA sequencing has transformed our understanding of genes, genomes and evolution. Which of the following statements comparing two common sequencing techniques, the chain termination method and next generation sequencing is TRUE? A) The chain termination method is faster and more efficient, so it is used to generate large-scale sequences, while next generation synthesis is used for routine, small-scale jobs. B) The chain termination method employs the polymerase chain reaction, but next generation sequencing does not. C) In the chain termination method, the order of bases is detected by fluorescently labeling each dideoxy-nucleotide in a different color, while next generation sequencing determines the order of bases by detecting the release of PPi during the formation of the phosphodiester bond. D) Next generation sequencing employs electrophoresis, but the chain termination method does not.

C) In the chain termination method, the order of bases is detected by fluorescently labeling each dideoxy-nucleotide in a different color, while next generation sequencing determines the order of bases by detecting the release of PPi during the formation of the phosphodiester bond.

Organisms share many conserved core processes and features, including transcription and translation using a uniform genetic code. Scientists have used these shared processes and features in biotechnology. For example, for the process of some transformations, a plasmid is constructed when a eukaryotic gene of interest is added with an antibiotic resistant gene such beta-lactamase, which is used for ampicillin resistance. This plasmid is then inserted into a prokaryotic bacterial cell, such as E-coli, through a transformation process that leads to the production of the product protein from the eukaryotic organism. To culture the bacteria and obtain the protein product, the bacteria must grow. Select the appropriate condition to determine if the plasmid has entered the E-coli bacterial cell. A) Nutrient broth to which no antibiotic has been added. B) Water to which ampicillin has been added. C) Nutrient broth to which ampicillin has been added. D) Nutrient broth to which other resistant bacteria have been added.

C) Nutrient broth to which ampicillin has been added.

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is also found in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following? A) Pax-6 genes are identical in nucleotide sequence. B) PAX-6 proteins have identical amino acid sequences. C) Pax-6 is highly conserved and shows shared evolutionary ancestry. D) PAX-6 proteins are different for formation of different kinds of eyes.

C) Pax-6 is highly conserved and shows shared evolutionary ancestry.

For a repressible operon to be transcribed, which of the following must occur? A) A corepressor must be present. B) RNA polymerase and the active repressor must be present. C) RNA polymerase must bind to the promoter, and the repressor must be inactive. D) RNA polymerase must not occupy the promoter, and the repressor must be inactive.

C) RNA polymerase must bind to the promoter, and the repressor must be inactive.

In 2009, a flu pandemic was believed to have originated when viral transmission occurred from pig to human, thereby earning the designation, "swine flu." Although pigs are thought to have been the breeding ground for the 2009 virus, sequences from bird, pig, and human viruses were all found within this newly identified virus. What is the most likely explanation of why this virus contained sequences from bird, pig, and human viruses? A) The virus was descended from a common ancestor of bird, pig, and human flu viruses. B) The infected individuals happened to be infected with all three virus types. C) Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly. D) The human was likely infected with various bacterial strains that contained all three RNA viruses.

C) Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly.

Imagine that you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype do you predict for this mutant? A) The mutant will grow rapidly. B) The mutant will require galactose for growth. C) The mutant will show low levels of gene expression. D) The mutant will show high levels of gene expression.

C) The mutant will show low levels of gene expression.

According to the central dogma, what molecule should go in the blank? DNA → _____ → Proteins A) mtDNA B) rRNA C) mRNA D) tRNA

C) mRNA

Which of the following statements describes the lysogenic cycle of lambda (λ) phage? A) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. B) Most of the prophage genes are activated by the product of a particular prophage gene. C) The phage genome replicates along with the host genome. D) The phage DNA is copied and exits the cell as a phage.

C) The phage genome replicates along with the host genome.

Which of the following is one of the technical reasons why gene therapy is problematic? A) Most cells with an engineered gene do not produce gene product. B) Cells with transferred genes are unlikely to replicate. C) Transferred genes may not have appropriately controlled activity. D) mRNA from transferred genes cannot be translated.

C) Transferred genes may not have appropriately controlled activity.

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because _____. A) it allows researchers to use the sequence to build a "better" nematode, which is resistant to disease B) it allows research on a group of organisms we do not usually care much about C) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates D) a sequence that is found to have no introns in the nematode genome is likely to have acquired the introns from higher organisms

C) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates

Of the following, which is the most current description of a gene? A) a unit of heredity that causes formation of a phenotypic characteristic B) a DNA subunit that codes for a single complete protein C) a DNA sequence that is expressed to form a functional product: either RNA or polypeptide D) a discrete unit of hereditary information that consists of a sequence of amino acids

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

Which of the following types of mutation would convert a proto-oncogene into an oncogene? A) a mutation that blocks transcription of the proto-oncogene B) a mutation that creates an unstable proto-oncogene mRNA C) a mutation that greatly increases the amount of the proto-oncogene protein D) a deletion of most of the proto-oncogene coding sequence

C) a mutation that greatly increases the amount of the proto-oncogene protein

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for _____. A) a particular gene that is amplified in all or most of the patient samples B) a pattern of fluorescence that indicates which cells are over proliferating C) a pattern shared among some or all of the samples that indicates gene expression differing from control samples D) a group of cDNAs that match those in non-breast cancer control samples from the same population

C) a pattern shared among some or all of the samples that indicates gene expression differing from control samples

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in _____. A) a base-pair substitution B) a frameshift mutation C) a polypeptide missing an amino acid D) a nonsense mutation

C) a polypeptide missing an amino acid

DNA microarrays have made a huge impact on genomic studies because they _____. A) can be used to eliminate the function of any gene in the genome B) can be used to introduce entire genomes into bacterial cells C) allow the expression of many or even all of the genes in the genome to be compared at once D) allow physical maps of the genome to be assembled in a very short time

C) allow the expression of many or even all of the genes in the genome to be compared at once

Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by _____. A) organizing gene expression, so that genes are expressed in a given order B) allowing each gene to be expressed an equal number of times C) allowing an organism to adjust to changes in environmental conditions D) allowing environmental changes to alter a prokaryote's genome

C) allowing an organism to adjust to changes in environmental conditions

Not long ago, it was believed that a count of the number of protein-coding genes would provide a count of the number of proteins produced in any given eukaryotic species. This is incorrect, largely due to the discovery of widespread _____. A) chromatin condensation control B) transcriptional control C) alternative splicing D) translational control

C) alternative splicing

The primary difference between enhancers and promoter-proximal elements is that enhancers _____. A) are transcription factors; promoter-proximal elements are DNA sequences B) enhance transcription; promoter-proximal elements inhibit transcription C) are at considerable distances from the promoter; promoter-proximal elements are close to the promoter D) are DNA sequences; promoter-proximal elements are proteins

C) are at considerable distances from the promoter; promoter-proximal elements are close to the promoter

A principal problem with inserting an unmodified mammalian gene into a plasmid and then getting that gene expressed in bacteria is that _____. A) prokaryotes use a different genetic code from that of eukaryotes B) bacteria translate only mRNAs that have multiple messages C) bacteria cannot remove eukaryotic introns D) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA

C) bacteria cannot remove eukaryotic introns

Translation requires _____. A) mRNA, tRNA, DNA, and rRNA B) mRNA, DNA, and rRNA C) mRNA, tRNA, and rRNA D) mRNA, tRNA, and DNA

C) mRNA, tRNA, and rRNA

The first class of drugs developed to treat AIDS, such as AZT, were known as reverse transcriptase inhibitors. They worked because they _____. A) targeted and destroyed the viral genome before it could be reverse transcribed into DNA B) bonded to the dsDNA genome of the virus in such a way that it could not separate for replication to occur C) bonded to the viral reverse transcriptase enzyme, thus preventing the virus from making a DNA copy of its RNA genome D) prevented host cells from producing the enzymes used by the virus to replicate its genome

C) bonded to the viral reverse transcriptase enzyme, thus preventing the virus from making a DNA copy of its RNA genome

What would occur if the repressor of an inducible operon were mutated so that it could not bind the operator? A) irreversible binding of the repressor to the promoter B) reduced transcription of the operon's genes C) continuous transcription of the operon's genes D) overproduction of catabolite activator protein (CAP)

C) continuous transcription of the operon's genes

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of a bacteriophage? A) regulation via acetylation of histones B) positive control mechanisms rather than negative C) control of more than one gene in an operon D) reliance on transcription activators

C) control of more than one gene in an operon

Which of the following accounts for someone who has had regular herpesvirus-mediated cold sore or genital sore flare-ups? A) re-infection by a closely related herpesvirus of a different strain B) re-infection by the same herpesvirus strain C) copies of the herpesvirus genome permanently maintained in host nuclei D) copies of the herpesvirus genome permanently maintained in host cell cytoplasm

C) copies of the herpesvirus genome permanently maintained in host nuclei

Which of the following are maternal effect genes that control the orientation of the egg and thus the Drosophila embryo? A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens

C) egg-polarity genes

Tumor-suppressor genes _____. A) are frequently overexpressed in cancerous cells B) are cancer-causing genes introduced into cells by viruses C) encode proteins that help prevent uncontrolled cell growth D) often encode proteins that stimulate the cell cycle

C) encode proteins that help prevent uncontrolled cell growth

DNA methylation and histone acetylation are examples of _____. A) genetic mutation B) chromosomal rearrangements C) epigenetic phenomena D) translocation

C) epigenetic phenomena

In 1997, Dolly the sheep was cloned. Which of the following processes was used? A) replication and dedifferentiation of adult stem cells from sheep bone marrow B) separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe C) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate D) isolation of stem cells from a lamb embryo and production of a zygote equivalent

C) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

A signal peptide _____. A) directs an mRNA molecule into the cisternal space of the ER B) terminates translation of messenger RNA C) helps target a protein to the ER D) signals the initiation of transcription

C) helps target a protein to the ER

Mutations in which of the following genes lead to transformations in the identity of entire body parts? A) segmentation genes B) egg-polarity genes C) homeotic genes D) inducers

C) homeotic genes

A nonsense mutation in a gene _____. A) changes an amino acid in the encoded protein B) has no effect on the amino acid sequence of the encoded protein C) introduces a premature stop codon into the mRNA D) alters the reading frame of the mRNA

C) introduces a premature stop codon into the mRNA

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. Many people were surprised that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for much of the DNA that is not coding for proteins? A) DNA that consists of histone coding sequences B) DNA that is translated directly without being transcribed C) non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function D) non-protein-coding DNA that serves as binding sites for reverse transcriptase

C) non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

A cell is considered to be differentiated when it _____. A) replicates by the process of mitosis B) loses connections to the surrounding cells C) produces proteins specific to a particular cell type D) appears to be different from the surrounding cells

C) produces proteins specific to a particular cell type

A laboratory might use dideoxyribonucleotides to _____. A) separate DNA fragments B) produce cDNA from mRNA C) sequence a DNA fragment D) visualize DNA expression

C) sequence a DNA fragment

The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different _____. A) genes B) regulatory sequences C) sets of regulatory proteins D) promoters

C) sets of regulatory proteins

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? A) start and stop codons B) ribosomes and tRNA C) several transcription factors D) aminoacyl-tRNA synthetase

C) several transcription factors

Proto-oncogenes _____. A) normally suppress tumor growth B) are produced by somatic mutations induced by carcinogenic substances C) stimulate normal cell growth and division D) are underexpressed in cancer cells

C) stimulate normal cell growth and division

The lactose operon is likely to be transcribed when _____. A) there is more glucose in the cell than lactose B) there is glucose but no lactose in the cell C) the cyclic AMP and lactose levels are both high within the cell D) the cAMP level is high and the lactose level is low

C) the cyclic AMP and lactose levels are both high within the cell

The virus genome and viral proteins are assembled into virions (virus particles) during _____. A) the lytic cycle and the lysogenic cycle in all known host organisms B) the lysogenic cycle only C) the lytic cycle only D) the lytic cycle in all host organisms but the lysogenic cycle only in bacteria

C) the lytic cycle only

Which of the following is directly related to a single amino acid? A) the base sequence of the tRNA B) the amino acetyl tRNA synthase C) the three-base sequence of mRNA D) the complementarity of DNA and RNA

C) the three-base sequence of mRNA

In the structural organization of many eukaryotic genes, individual exons may be related to which of the following? A) the sequence of the intron that immediately precedes each exon B) the number of polypeptides making up the functional protein C) the various domains of the polypeptide product D) the number of start sites for transcription

C) the various domains of the polypeptide product

Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure? A) replication rate B) transcription rate C) translation rate D) formation of new transcription factors

C) translation rate

Which of the following contradicts the one-gene, one-enzyme hypothesis? A) A mutation in a single gene can result in a defective protein. B) Alkaptonuria results when individuals lack a single enzyme involved in the catalysis of homogentisic acid. C) Sickle-cell anemia results in defective hemoglobin. D) A single antibody gene can code for different related proteins, depending on the splicing that takes place post-transcriptionally.

D) A single antibody gene can code for different related proteins, depending on the splicing that takes place post-transcriptionally.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is _____. A) TTT B) UUA C) UUU D) AAA

D) AAA

Which of the following best reflects what we know about how the flu virus moves between species? A) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. B) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. C) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. D) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans

D) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans

Plasmids are used as vectors in plant and bacterial genetic engineering. However, there is a major difference in the fate of genes introduced into bacteria on most bacterial plasmids and into plants on tumor-inducing (Ti) plasmids. What is this difference? A) In bacteria, genes are stably expressed; in plants, gene expression is always lost quickly. B) Gene expression tends to decrease rapidly and unpredictably in bacteria; gene expression is much more stable in plants. C) Bacterial plasmids are circular DNAs; Ti plasmid DNA is linear. D) Bacterial plasmids and the genes they carry usually are not integrated into the chromosome; Ti plasmids and the genes they carry are integrated into the chromosome.

D) Bacterial plasmids and the genes they carry usually are not integrated into the chromosome; Ti plasmids and the genes they carry are integrated into the chromosome.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following would be likely? A) The three structural genes will be expressed normally. B) RNA polymerase will no longer transcribe permease. C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. D) Beta galactosidase will not be produced.

D) Beta galactosidase will not be produced.

CAP is said to be responsible for positive regulation of the lac operon because _____. A) CAP binds cAMP B) CAP binds to the CAP-binding site C) CAP prevents binding of the repressor to the operator D) CAP bound to the CAP-binding site increases the frequency of transcription initiation

D) CAP bound to the CAP-binding site increases the frequency of transcription initiation

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare? A) Prokaryotic codons usually contain different bases than those of eukaryotes. B) Prokaryotic codons usually specify different amino acids than those of eukaryotes. C) The translation of codons is mediated by tRNAs in eukaryotes, but translation requires no intermediate molecules such as tRNAs in prokaryotes. D) Codons are a nearly universal language among all organisms.

D) Codons are a nearly universal language among all organisms.

Which of the following is in the correct order for one cycle of polymerase chain reaction (PCR)? A) Denature DNA; add fresh enzyme; anneal primers; add dNTPs; extend primers. B) Anneal primers; denature DNA; extend primers. C) Extend primers; anneal primers; denature DNA. D) Denature DNA; anneal primers; extend primers.

D) Denature DNA; anneal primers; extend primers.

Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problems? I. the possibility that, once introduced into the patient, the iPS cells produce nonpancreatic cells II. the failure of the iPS cells to take up residence in the pancreas III. the inability of the iPS cells to respond to appropriate regulatory signals A) I only B) II only C) III only D) I, II, and III

D) I, II, and III

The final step in a Sanger DNA sequencing reaction is to run the DNA fragments on a gel. What purpose does this serve? A) It adds ddNTP to the end of each DNA fragment. B) It changes the length of the DNA fragments. C) It separates DNA fragments based on their charge. D) It separates DNA fragments generated during the sequencing reaction based on onenucleotide differences in their size.

D) It separates DNA fragments generated during the sequencing reaction based on one nucleotide differences in their size.

What does it mean when we say the genetic code is redundant? A) A single codon can specify the addition of more than one amino acid. B) The genetic code is different for different domains of organisms. C) The genetic code is universal (the same for all organisms). D) More than one codon can specify the addition of the same amino acid.

D) More than one codon can specify the addition of the same amino acid.

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its cap and poly-A tail. Which of the following would you expect her to find? A) The mRNA is quickly converted into a ribosomal subunit. B) The cell adds a new poly-A tail to the mRNA. C) The mRNA attaches to a ribosome and is translated, but more slowly. D) The molecule is digested by enzymes because it is not protected at the end.

D) The molecule is digested by enzymes because it is not protected at the end.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is exposed to lactose? A) The inducer will no longer bind to the repressor. B) The repressor will no longer bind to the operator. C) The operon will never be transcribed. D) The structural genes will be transcribed continuously.

D) The structural genes will be transcribed continuously.

The herpes viruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can later reactivate, replicate again, and infect others. In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations? \ A) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. B) The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. C) Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage. D) The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus.

D) The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus.

Evidence suggests that factors which contribute towards the virulence of E. coli strain O157:H7, a bacterial strain reported to cause several food poisoning deaths, are caused by genes from a virus that infects bacteria. Considering this evidence, which statement most likely explains how the O157:H7 population acquired the genetic variation that distinguishes the strain from harmless E. coli strains, such as those that reside in our intestines? A) The virus entered the bacterial cell and incorporated its DNA into the bacterial genome, allowing the bacteria's cellular machinery to create new viruses. B) Viral envelope proteins bind to receptors on the bacterial membrane, allowing the viral genetic material to enter the bacterium and become translated into proteins. C) The virus entered the cell and acquired specific genes from the bacteria to increase the virulence of the virus. D) The virus infected the bacterium, and allowed the bacterial population to replicate with a copy of the phage genome in each new bacterium.

D) The virus infected the bacterium, and allowed the bacterial population to replicate with a copy of the phage genome in each new bacterium.

In animals, what is the difference between reproductive cloning and therapeutic cloning? A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not. B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not. C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated nonfertilized eggs. D) Therapeutic cloning supplies cells for repair of diseased or injured organs

D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

In animals, what is the difference between reproductive cloning and therapeutic cloning? A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not. B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not. C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated nonfertilized eggs. D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent because _____. A) the cloning was done poorly and it was likely that some contaminating cat DNA became part of Carbon Copy's genome B) fur color genes in cats is determined by differential acetylation patterns C) cloned animals have been found to have a higher frequency of transposon activation D) X inactivation in the embryo is random and produces different patterns

D) X inactivation in the embryo is random and produces different patterns

Post-translational modifications of proteins may include the _____. A) removal of introns B) addition of a 5' cap C) addition of a poly-A tail D) addition of carbohydrates to form a glycoprotein

D) addition of carbohydrates to form a glycoprotein

Yeast cells are frequently used as hosts for cloning because they _____. A) easily form colonies B) can remove exons from mRNA C) do not have plasmids D) are eukaryotic cells

D) are eukaryotic cells

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the _____. A) binding of ribosomes to mRNA B) binding of the anticodon to small subunit of the ribosome C) attachment of amino acids to rRNAs D) binding of the anticodon to the codon and the attachment of amino acids to tRNAs

D) binding of the anticodon to the codon and the attachment of amino acids to tRNAs

Steroid hormones produce their effects in cells by _____. A) activating key enzymes in metabolic pathways B) activating translation of certain mRNAs C) promoting the degradation of specific mRNAs D) binding to intracellular receptors and promoting transcription of specific genes

D) binding to intracellular receptors and promoting transcription of specific genes

One way to detect alternative splicing of transcripts from a given gene is to _____. A) compare the DNA sequence of the given gene to that of a similar gene in a related organism B) measure the relative rates of transcription of the given gene compared to that of a gene known to be constitutively spliced C) compare the sequences of different primary transcripts made from the given gene D) compare the sequences of different mRNAs made from the given gene

D) compare the sequences of different mRNAs made from the given gene

Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria? A) control of chromatin remodeling B) control of RNA splicing C) transcriptional control D) control of both RNA splicing and chromatin remodeling

D) control of both RNA splicing and chromatin remodeling

A lack of which molecule would result in a cell's inability to "turn off" genes? A) operon B) inducer C) promoter D) corepressor

D) corepressor

You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal to analyze the substance and determine the nature of the infectious agent. I. Treat the substance with enzymes that destroy all nucleic acids and then determine whether the substance is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance on nutritive medium, away from any plant cells. IV. Treat the sample with proteases that digest all proteins and then determining whether the substance is still infectious. If you already know that the infectious agent was either a viroid or a prion, which method(s) listed above would allow you to distinguish between these two possibilities? A) I only B) II only C) IV only D) either I or IV

D) either I or IV

Forms of the Ras protein found in tumors usually cause which of the following? A) DNA replication to stop B) cell-to-cell adhesion to be nonfunctional C) cell division to cease D) excessive cell division

D) excessive cell division

An original section of DNA has the base sequence AGCGTTACCGT. A mutation in this DNA strand results in the base sequence AGGCGTTACCGT. This change represents _____. A) a missense mutation B) a point mutation C) a silent mutation D) frameshift mutation

D) frameshift mutation

Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because _____. A) metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies B) enzymes are made of DNA, and affected individuals lack DNA polymerase C) certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors D) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes

D) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzyme

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture One of her colleagues suggested she try increased methylation of C nucleotides in the DNA of promoters of a mammalian system. Which of the following results would she most likely see? A) decreased chromatin condensation B) activation of histone tails for enzymatic function C) higher levels of transcription of certain genes D) inactivation of the selected genes

D) inactivation of the selected genes

Using retroviral vectors for gene therapy might increase the patient's risk of developing cancer because they might _____. A) introduce proteins from the virus B) not express the genes that were introduced into a patient's cells C) not integrate their recombinant DNA into the patient's genome D) integrate recombinant DNA into the genome in ways that misregulate the expression of genes at or near the site of integration

D) integrate recombinant DNA into the genome in ways that misregulate the expression of genes at or near the site of integration

In the form of gene therapy used successfully for severe combined immunodeficiency syndrome (SCID)-X1, the genetic engineering of human cells is done by _____. A) injecting engineered viruses into the patient's bloodstream B) injecting engineered viruses into the patient's bone marrow C) treating a relative's cultured bone marrow cells with genetically engineered viruses and then injecting these cells into the patient's bone marrow D) isolating the patient's bone marrow cells, infecting them with genetically engineered viruses, and injecting them back into the patient's bone marrow

D) isolating the patient's bone marrow cells, infecting them with genetically engineered viruses, and injecting them back into the patient's bone marrow

Gene therapy requires _____. A) knowledge and availability of the normal allele of the defective gene B) the ability to introduce the normal allele into the patient C) the ability to express the introduced gene at the correct level, time, and tissue site within the patient D) knowledge and availability of the normal allele of the defective gene, an ability to introduce the normal allele into the patient, and an ability to express the introduced gene at the correct level, and time, and tissue site within the patient

D) knowledge and availability of the normal allele of the defective gene, an ability to introduce the normal allele into the patient, and an ability to express the introduced gene at the correct level, and time, and tissue site within the patient

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the repressor gene (lacI), along with its promoter, to a position at some several thousand base pairs away from its normal position, we would expect the _____. A) repressor will no longer bind to the operator B) repressor will no longer bind to the inducer C) lac operon will be expressed continuously D) lac operon will function normally

D) lac operon will function normally

What are prions? A) mobile segments of DNA B) tiny circular molecules of RNA that can infect plants C) viral DNA that attaches itself to the host genome and causes disease D) misfolded versions of normal protein that can cause disease

D) misfolded versions of normal protein that can cause disease

Which of the following is most like the formation of identical twins? A) cell cloning B) therapeutic cloning C) use of adult stem cells D) organismal cloning

D) organismal cloning

Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development? A) morphogenesis B) determination C) differentiation D) pattern formation

D) pattern formation

Many identical copies of genes cloned in bacteria are produced as a result of _____. A) plasmid replication B) bacterial cell replication C) transformation D) plasmid and bacterial cell replication

D) plasmid and bacterial cell replication

Extracellular glucose inhibits transcription of the lac operon by _____. A) strengthening the binding of the repressor to the operator B) weakening the binding of the repressor to the operator C) inhibiting RNA polymerase from opening the strands of DNA to initiate transcription D) reducing the levels of intracellular cAMP

D) reducing the levels of intracellular cAMP

The product of the bicoid gene in Drosophila provides essential information about _____. A) the dorsal-ventral axis B) the left-right axis C) segmentation D) the anterior-posterior axis

D) the anterior-posterior axis

The host range of a virus is determined by _____. A) the enzymes carried by the virus B) whether its nucleic acid is DNA or RNA C) the proteins in the host's cytoplasm D) the proteins on its surface and that of the host

D) the proteins on its surface and that of the host

Gene expression is often assayed by measuring the level of mRNA produced from a gene. If one is interested in knowing the amount of a final active gene product, a potential problem of this method is that it ignores the possibility of _____. A) chromatin condensation control B) transcriptional control C) alternative splicing D) translational control

D) translational control