Questions and Answers of Structural Analysis

When a cloned gene is inserted into a noncritical site in the mouse genome by homologous recombination, the result isa. gene addition.b. gene modification.c. gene knockout.d. both a and b.
One strategy for producing a protein in the milk of a cow is to place the coding sequence of the gene of interest next to a __________ and then inject the gene into a _________.a. lac operon
During mammalian reproductive cloning, _________ is fused with __________.a. a somatic cell, a stem cellb. a somatic cell, an egg cellc. a somatic cell, an enucleated egg celld. an enucleated somatic
Which of the following is a key feature of stem cells?a. They have the ability to divide.b. They have the ability to differentiate.c. They are always pluripotent.d. Both a and b are true of stem
When A. tumefaciens is used to make a transgenic plant, a gene of interest is inserted into a _________, which is first transformed into __________. The __________ is then transferred to a plant.a.
In addition to the use of T-DNA vectors, other methods to produce transgenic plants includea. biolistic gene transfer.b. microinjection.c. electroporation.d. all of the above.
R esearchers can introduce loss-of-function mutations into genes using the CRISPR/Cas technology described in Chapter 20. If you used this technology to produce a homozygous loss-of-function mutation
A protein called trypsin, which plays a role in digestion in vertebrates, is made by pancreatic cells and secreted from those cells. Starting with a sample of pancreatic cells, a researcher modified
In the experiment presented in Figure 17.5, were Fire and Mello injecting pre-miRNA or pre-siRNA? Explain.Figure 17.5 a Sense RNA Experimental level Single row of eggs- Add RNA polymerase and
Explain how the data of Fire and Mello suggested that doublestranded RNA is responsible for the silencing of mex-3 mRNA.
The CRISPR-Cas system has been modified so that it can be used as a gene editing tool (look ahead to Figure 20.13). Describe how that tool works, and explain how the natural CRISPR-Cas system is
Compare and contrast anti-miRNA oligonucleotides (AMOs), locked nucleic acids (LNAs), and antagomirs, which may eventually be used to treat certain forms of cancer.
What is miRNA replacement therapy? Describe three examples of this treatment approach.
What is a common feature found in all viruses?a. An envelopeb. DNAc. Nucleic acid surrounded by a protein capsidd. All of the above are common features.
Viral genomes can bea. DNA or RNA.b. single-stranded or double-stranded.c. linear or circular.d. All of the above can characterize a viral genome.
Which of the following is a common order of the steps in a viral reproductive cycle? (Integration is an optional step.)a. Entry, integration, attachment, synthesis of viral components, viral
An example of an emerging virus isa. phage λ.b. HIV, which causes AIDS.c. a strain of influenza virus called H1N1 that causes the flu.d. Both b and c are emerging viruses.
A mutation in phage λ results in a 10-fold increase of transcription of the cII gene. How do you think this mutation would affect the reproductive cycle of the phage?a. The lytic cycle would be
The cI gene that encodes the λ repressor has two promoters designated PRE and PRM. Which of the following statements is false?a. PRE is activated by the cII protein.b. PRE is activated by the λ
A viral protein that is needed to make HIV DNA isa. integrase.b. reverse transcriptase.c. Vpr.d. Gag polyprotein.
Which form of HIV RNA is packaged into HIV particles?a. Fully spliced RNAb. Incompletely spliced RNAc. Unspliced RNAd. All three forms of RNA are packaged into HIV particles.
After HIV components are made, what is the correct order of the stages that produce mature HIV particles?a. Maturation, budding, assemblyb. Maturation, assembly, buddingc. Assembly, budding,
What technique must be used to visualize a virus?
Following the infection of healthy tobacco leaves by reconstituted viruses, what two characteristics did Fraenkel-Conrat and Singer analyze? Explain how their results were consistent with the idea
Certain drugs to combat human viral diseases affect spike glycoproteins in the viral envelope. Discuss how you think such drugs may prevent viral infection.
Some drugs that inhibit HIV proliferation are inhibitors of HIV protease. Explain how these drugs would help to stop the spread of HIV.
A researcher identified a mutation in PR of phage λ that causes its transcription rate to be increased 10-fold. Do you think this mutation would favor the lytic or lysogenic cycle? Explain your
Experimentally, when an E. coli bacterium already has a λ prophage integrated into its chromosome, another λ phage cannot usually infect the cell and establish the lysogenic or lytic cycle. Based
A mutation changes a codon that specifies tyrosine into a stop codon. This type of mutation is aa. missense mutation.b. nonsense mutation.c. frameshift mutation.d. neutral mutation.
A down promoter mutation causes the promoter of a gene to be _______ like the consensus sequence and _________ transcription.a. less, stimulatesb. more, stimulatesc. less, inhibitsd. more, inhibits
A mutation in one gene that reverses the phenotypic effects of a mutation in a different gene isa. an intergenic suppressor.b. an intragenic suppressor.c. an up promoter mutation.d. a position effect.
Which of the following is an example of a somatic mutation?a. A mutation in an embryonic muscle cellb. A mutation in a sperm cellc. A mutation in an adult nerve celld. Both a and c are examples of
In the replica-plating experiments of the Lederbergs, bacterial colonies appeared at the same locations on each of two secondary plates becausea. T1 phage caused the mutations to happen.b. the
Which of the following is not an example of a spontaneous mutation?a. A mutation caused by an error in DNA replicationb. A mutation caused by a tautomeric shiftc. A mutation caused by UV lightd. All
A point mutation could be caused bya. depurination.b. deamination.c. tautomeric shift.d. any of the above.
One way that TNRE may occur involves the formation of _________ that disrupts ____________.a. a double-strand break, chromosome segregationb. an apurinic site, DNA replicationc. a hairpin, DNA
Nitrous acid replaces amino groups with keto groups, a process calleda. alkylation.b. deamination.c. depurination.d. crosslinking.
A mutagen that is a base analog isa. ethyl methanesulfonate (EMS).b. 5-bromouracil.c. UV light.d. proflavin.
In an Ames test, a ____________ number of colonies is observed if a substance ________ a mutagen, compared with the number of colonies for a control sample that is not exposed to the suspected
The function of photolyase is to repaira. double-strand breaks.b. apurinic sites.c. thymine dimers.d. all of the above.
Which of the following DNA repair systems may involve the removal of a segment of a DNA strand?a. Base excision repairb. Nucleotide excision repairc. Mismatch repaird. All of the above
In nucleotide excision repair in E. coli, the function of the UvrA/UvrB complex is toa. detect DNA damage.b. make cuts on both sides of the damage.c. remove the damaged piece of DNA.d. replace the
Double-strand breaks can be repaired bya. homologous recombination repair (HRR).b. nonhomologous end joining (NHEJ).c. nucleotide excision repair (NER).d. either a or b.
An advantage of translesion-replicating polymerases is that they can replicate _________________, but a disadvantage is that they _________________.a. very quickly, have low fidelityb. over damaged
Homologous recombination refers to the exchange of DNA segments that area. similar or identical in their DNA sequences.b. in close proximity to one another.c. broken due to ionizing radiation.d.
During the molecular process of homologous recombination between homologous chromosomes,a. a Holliday junction forms.b. branch migration occurs.c. a heteroduplex region forms.d. all of the above
A key difference between the original Holliday model and the double-strand break model is the way thata. the DNA strands are initially broken.b. branch migration occurs.c. a heteroduplex is formed.d.
Which of the following mechanisms can result in gene conversion?a. DNA mismatch repairb. DNA gap repairc. Resolution of a Holliday junctiond. Both a and b can result in gene conversion.
Explain how the use of the technique of replica plating supported the random mutation theory and not the physiological adaptation hypothesis.
Which of the following may be used as a vector in a gene-cloning experiment?a. mRNAb. Plasmidc. Virusd. Either b or c
The restriction enzymes used in gene-cloning experiments ___________, which generates sticky ends that can ___________.a. cut the DNA, enter bacterial cellsb. cut the DNA, hydrogen bond with
Which is the proper order of the following steps in a genecloning experiment involving vectors?1. Add DNA ligase.2. Incubate the chromosomal DNA and the vector DNA with a restriction enzyme.3.
The function of reverse transcriptase is toa. use RNA as a template to make DNA.b. use DNA as a template to make RNA.c. translate RNA into protein.d. translate DNA into protein.
A collection of recombinant vectors that carry fragments of chromosomal DNA is calleda. a genomic library.b. a cDNA library.c. a Northern blot.d. either a or b.
In one PCR cycle, the correct order of steps isa. primer annealing, primer extension, denaturation.b. primer annealing, denaturation, primer extension.c. denaturation, primer annealing, primer
In reverse transcriptase PCR, the starting biological material isa. chromosomal DNA.b. mRNA.c. proteins.d. all of the above.
During real-time PCR, the synthesis of PCR products is analyzeda. at the very end of the reaction by gel electrophoresis.b. at the very end of the reaction by fluorescence that is emitted within the
When a dideoxyribonucleotide is incorporated into a growing DNA strand,a. the strand elongates faster.b. the strand cannot elongate.c. the strand becomes more susceptible to DNase I cleavage.d. none
The purpose of site-directed mutagenesis and CRISPR-Cas technology is toa. determine if a protein binds to a DNA segment.b. determine the sequence of a segment of DNA.c. alter the sequence of a
Which of the following methods use(s) a labeled nucleic acid probe, such as a labeled fragment of DNA?a. Site-directed mutagenesis c. Western blottingb. Northern blotting
Which of the following methods is used to detect a specific RNA within a mixture of many different RNAs?a. Site-directed mutagenesis c. Western blottingb. Northern blotting
During Western blotting, the primary antibody recognizesa. the secondary antibody.b. the protein of interest.c. an mRNA of interest.d. a specific fragment of chromosomal DNA.
In an EMSA, the binding of a protein to DNAa. prevents the DNA from being digested with a restriction enzyme.b. causes the DNA to migrate more slowly through a gel.c. causes the DNA to migrate more
The basis for DNase I footprinting is that the binding of a protein to DNAa. prevents the DNA from being digested with a restriction enzyme.b. enhances the ability of the DNA to be digested with a
Site-directed mutagenesis is used to explore the structure and function of proteins. For example, changes can be made to the coding sequence of a gene to determine how alterations in the amino acid
The likelihood of any particular base in a given position is 1/4 (because there are 4 types of bases) and the likelihood of a purine is 1/2. If you assume random base arrangements, the likelihood of
An electrophoretic mobility shift assay (EMSA) can be used to determine if a protein binds to a segment of DNA. When a segment of DNA is bound by a protein, its mobility will be slowed down, and the
If an abnormal repressor protein could still bind allolactose but the binding of allolactose did not alter the conformation of lac repressor, how would the expression of the lac operon be affected?
Would a mutation that inactivated lac repressor and prevented it from binding to the lac operator site result in the constitutive expression of the lac operon under all conditions? Explain. What is
Suppose that you have isolated a mutant strain of E. coli in which the lac operon is constitutively expressed. To understand the nature of this defect, you create a merozygote in which the mutant
A release factor is referred to as a “molecular mimic” because its structure is similar to that ofa. a ribosome.b. an mRNA.c. a tRNA.d. an elongation factor.
Describe the structure of a polysome, which is depicted in Figure 13.13a.Figure 13.13a. (a) Ribosomes in the act of translation Ribosome Polypeptide mRNA If 0.1 pm
L et’s suppose you have isolated chromatin from some bizarre eukaryote that has a DNA linker region that is usually 300–350 bp in length. The nucleosome structure is the same as in other
In the experiment in Figure 6.6, Stern studied the inheritance pattern of crosses in which female fruit flies carried two abnormal X chromosomes, in order to find a relationship between genetic
By conducting conjugation experiments between Hfr and recipient strains, Wollman and Jacob mapped the order of many bacterial genes. Throughout the course of their studies, they identified several
An Hfr strain that is leuA+ and thiL+ was mixed with a strain that is leuA− and thiL−. The data points in the following graph were obtained when conjugation was interrupted at different time
In the experiment of Figure 7.1, a met− bio− thr+ leu+ thi+ cell could become met+ bio+ thr+ leu+ thi+ by a (rare) double mutation that converts the met− bio− genes into met+ bio+. Likewise,
In the experiment of Figure 7.1, Lederberg and Tatum could not discern whether met+ bio+ genetic material was transferred to the met− bio− thr+ leu+ thi+ strain or if thr+ leu+ thi+ genetic
What is the main goal of comparative genomic hybridization? Explain how the ratio of green to red fluorescence observed along a chromosome provides information about chromosome structure.
Describe how colchicine can be used to alter chromosome number.
The process of binary fission begins with a single mother cell and ends with two daughter cells. Would you expect the mother and daughter cells to be genetically identical? Explain why or why not.
How would you set up crosses to determine if a gene is Y-linked versus X-linked?
Occasionally during meiosis, a mistake results in a gamete receiving zero or two sex chromosomes rather than one. Bridges made a cross between white-eyed female flies and red-eyed male flies. As you
With regard to thickness and length, what do you think chromosomes would look like if you microscopically examined them during interphase? How would that compare with their appearance during
A rare form of dwarfism that also included hearing loss was found to run in a particular family. It is inherited as a dominant trait. It was discovered that an affected individual had one normal copy
Female flies with white eyes and miniature wings (both X-linked recessive traits) were crossed to male flies with red eyes and long wings. On rare occasions, female offspring with white eyes were
Mexican hairless dogs have little hair and few teeth. When a Mexican hairless is mated to another breed of dog, about half of the puppies are hairless. When two Mexican hairless dogs are mated to
In chickens, some varieties have feathered shanks (legs), but others do not. In a cross between a Black Langshan (feathered shanks) and a Buff Rock (unfeathered shanks), the shanks of the F1
In the clover butterfly, males are always yellow, but females can be yellow or white. In females, white is a dominant allele. Two yellow butterflies were crossed to yield an F1 generation consisting
The Mic2 gene in humans is present on both the X and Y chromosome.Let’s suppose the Mic2 gene exists in a dominant Mic2 allele, which results in normal surface antigen production, and a recessive
Duroc Jersey pigs are typically red, but a sandy phenotype also occurs. When two different strains of true-breeding sandy pigs were crossed to each other, they produced F1 offspring that were red.
Summer squash exist in long, spherical, or disk shapes. When a true-breeding long-shaped strain was crossed to a true-breeding disk-shaped strain, all of the F1 offspring were disk-shaped. When the
Red eyes is the wild-type phenotype in Drosophila, and several different genes (with each gene existing in two or more alleles) affect eye color. One allele causes purple eyes, and a different allele
As mentioned in question E11, red eyes is the wild-type phenotype in Drosophila. Several different genes (with each gene existing in two or more alleles) are known to affect eye color. One allele
Let’s suppose you were looking through a vial of fruit flies in your laboratory and noticed a male fly with pink eyes. What crosses would you make to determine if the pink allele is an X-linked
Figure 5.1 illustrates an example of a maternal effect. Explain how Sturtevant deduced a maternal effect gene based on the F2 and F3 generations.Figure 5.1 Parental generation F generation F
Discuss the types of experimental observations that Lyon brought together in proposing her hypothesis concerning X-chromosome inactivation. In your own words, explain how these observations were
Describes two blotting methods (i.e., Northern blotting and Western blotting) used to detect gene products. Northern blotting detects RNA and Western blotting detects proteins. Suppose that a female
Suppose that a trait in some mice is an unusually long tail. You initially have a true-breeding strain with normal-length tails and a true-breeding strain with long tails. You then make the following
On a camping trip on a uninhabited island, you find one male snail with a shell that coils to the right. However, in this same area, you find several shells (not containing living snails) that coil

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