Questions and Answers of Structural Analysis

What is a genetic cross?
The technique known as DNA sequencing (described in Chapter 20) enables researchers to determine the DNA sequence of genes. Would this technique be used primarily by transmission geneticists,
Why did Mendel’s work refute the blending hypothesis of inheritance?
What is the difference between cross-fertilization and self-fertilization?
How can you determine whether an organism is heterozygous or homozygous for a dominant trait?
In your own words, describe Mendel’s law of segregation. Do not use the word segregation in your answer.
With regard to genes in pea plants that we have considered in this chapter, which statement(s) is/are not correct?A. The gene causing tall plants is an allele of the gene causing dwarf plants.B. The
For a cross between a heterozygous tall pea plant and a dwarf plant, predict the ratios of the offspring’s genotypes and phenotypes.
Do you know the genotype of an individual exhibiting a recessive trait or of an individual exhibiting a dominant trait? Explain your answer.
A pea plant that is heterozygous with regard to seed color (yellow is dominant to green) is allowed to self-fertilize. What are the predicted outcomes of genotypes and phenotypes of the offspring?
Describe the significance of nonparental combinations of traits with regard to the law of independent assortment. In other words, explain how the appearance of nonparental combinations refutes the
Albinism, a condition characterized by a partial or total lack of skin pigment, is a recessive human trait. If a phenotypically unaffected couple produce an albino child, what is the probability that
List three advantages of using pea plants as an experimental organism.
Explain the technical difference between a cross-fertilization experiment and a self-fertilization experiment.
Would it be possible to deduce the law of independent assortment from a single-factor cross? Explain your answer.
The data with Figure 2.5 show the results of the F2 generation for seven of Mendel’s experiments. Conduct a chi square test to determine if these data are consistent with the law of
Scientists propose that the first macromolecules in protobionts werea. DNA molecules.b. RNA molecules.c. proteins.d. all of the above.
Which of the following function(s) is/are carried out by piRITS or piRISC?a. Inhibits transcription of TEsb. Causes the degradation of TE RNAc. Causes chromosome breakaged. Both a and b are functions
In the CRISPR-Cas system, what does tracrRNA bind to?a. crRNA and Cas1 proteinb. crRNA and Cas2 proteinc. crRNA and Cas9 proteind. Cas1 and Cas2 proteins
When facilitating the methylation or pseudouridylation of an rRNA, a snoRNA functions asa. a decoy.b. a scaffold.c. a guide.d. both b and c.
When an ncRNA functions as a decoy, ita. contains binding sites for many different proteins, thereby promoting the formation of a large complex.b. recognizes other ncRNAs and sequesters them, thereby
Suppose that the overexpression of a particular miRNA was associated with pancreatic cancer. Which of the following agents might be effective in treating this type of cancer?a. Enoxacinb. A DNA
Which of the following components are needed for the adaptation phase of the CRISPR-Cas system?a. crRNA and Cas1 proteinb. crRNA and Cas2 proteinc. crRNA and Cas9 proteind. Cas1 and Cas2 proteins
Which of the following is a function of SRP?a. Pausing translation of a polypeptide via an ER signal sequenceb. Binding to an SRP receptor in the ER membranec. Docking the ribosome over a channeld.
The process of RNA interference may lead toa. the degradation of an mRNA.b. the inhibition of translation of an mRNA.c. the synthesis of an mRNA.d. both a and b.
Which of the following functions does HOTAIR perform?a. Decoyb. Scaffoldc. Guided. Both b and c
Which of the following can bind to ncRNAs?a. DNAb. RNAc. Proteinsd. Small moleculese. All of the above
Abnormalities in the expression of ncRNAs are associated witha. many forms of cancer.b. neurological disorders.c. cardiovascular diseases.d. all of the above.
Epigenetic changes maya. be programmed during development.b. be caused by environmental factors.c. involve changes in the DNA sequence of a gene.d. Both a and b are true of epigenetic changes.
Which of the following statements is/are true regarding a barrier?a. A barrier stops the spreading of heterochromatin.b. A barrier forms a boundary between euchromatin and heterochromatin.c. A
Which of the following mechanisms may be involved when PRC1 complexes silence gene expression?a. The compaction of nucleosomesb. The attachment of ubiquitin to histone proteinsc. The direct
A form of chromatin that silences gene expression and varies in location among different types of cells isa. euchromatin.b. constitutive heterochromatin.c. facultative heterochromain.d. Both b and c
In one cell, gene C is expressed, whereas in another cell, gene C is inactive. After the cells are fused experimentally, both copies of gene C are expressed. This observation could be explained bya.
During the process of XCI, which chromosome expresses the Xist gene and which one expresses the Tsix gene?a. Xist is expressed only by Xa, and Tsix is expressed only by Xi.b. Xist is expressed only
If the VIN3 gene had a loss-of-function mutation, how do you think that would affect the phenotypes of summer-annual and winter-annual Arabidopsis plants?a. Neither type would flower.b. Both types
The effects of paramutation may vary with regard toa. the likelihood that the parmutagenic allele will alter the paramutable allele.b. the stability of the paramutagenic allele over the course of
Which of the following is not an important function of heterochromatin formation?a. Gene silencingb. Prevention of viral proliferationc. Splicing of pre-mRNAd. Prevention of movement of transposable
An epigenetic modification to a specific gene may initially be established bya. a transcription factor.b. a non-coding RNA.c. either a or b.d. none of the above.
For the Igf2 gene, where do de novo methylation and maintenance methylation occur?a. De novo methylation occurs in sperm, and maintenance methylation occurs in egg cells.b. De novo methylation occurs
When mice carrying the Avy allele exhibit a darker coat, this phenotype is thought to be caused by dietary factors that result ina. a higher level of DNA methylation and a decrease in the expression
Which of the following statements about paramutation is false?a. A paramutagenic allele can alter the expression of paramutable allele.b. A paramutagenic allele has a lower level of expression than
Heterochromatin is characterized by which of the following?a. Higher level of compactionb. Silencing of gene transcriptionc. Localization at the periphery of the cell nucleusd. All of the above are
Which of the following are examples of molecular changes that can have an epigenetic effect on gene expression?a. Chromatin remodelingb. Covalent histone modificationc. Localization of histone
Transcriptional activation of eukaryotic genes involves which of the following events?a. Changes in nucleosome locationsb. Changes in histone composition within nucleosomesc. Histone modificationsd.
Regulatory transcription factors can be modulated bya. the binding of small effector molecules.b. protein-protein interactions.c. covalent modifications.d. any of the above.
Which of the following characteristics is typical of a eukaryotic gene that can be transcribed?a. The core promoter is wrapped around a nucleosome.b. The core promoter is found in a nucleosome-free
A bidirectional enhancer has the following sequence:5′–GTCA–3′3′–CAGT–5′Which of the following sequences would also be a functional enhancer?a. 5′–ACTG–3′3′–TGAC–5′b.
The process in which completely unmethylated DNA becomes methylated is calleda. maintenance methylation.b. de novo methylation.c. primary methylation.d. demethylation.
According to the histone code hypothesis, the pattern of histone modifications acts like a language thata. influences chromatin structure.b. promotes transcriptional termination.c. inhibits the
A regulatory transcription factor protein typically contains _________ that binds to the ________ of the DNA.a. an α helix, backboneb. an α helix, major groovec. a β sheet, backboned. a β sheet,
The binding of iron regulatory protein (IRP) to the iron response element (IRE) in the 5′-UTR of the ferritin mRNA causesa. inhibition of translation of the ferritin mRNA.b. stimulation of
The overall goal of the ENCODE Project isa. to sequence the entire genome from many different people.b. to identify all of the functional elements in the human genome.c. to study the expression of
How can methylation affect transcription?a. It may prevent the binding of regulatory transcription factors.b. It may enhance the binding of regulatory transcription factors.c. It may promote the
A chromatin-remodeling complex maya. change the locations of nucleosomes.b. evict histones from DNA.c. replace standard histones with histone variants.d. do all of the above.
Combinatorial control refers to the phenomenon thata. transcription factors always combine with each other when regulating genes.b. the combination of many factors determines the expression of any
How does exposing an E. coli cell to glucose affect the regulation of the lac operon via CAP?a. cAMP binds to CAP and transcription is increased.b. cAMP binds to CAP and transcription is decreased.c.
Operons involved with the biosynthesis of molecules such as amino acids are most likely to be regulated in which of the following ways?a. The product of the biosynthetic pathway represses
On its chromosome, an E. coli cell has the genotype lacI− lacZ+ lacY+ lacA+. It has an F′ factor with the genotype lacI+ lacZ+ lacY+ lacA+. What is the expected level of expression of the lac
An example of a posttranslational covalent modification that may affect protein function isa. phosphorylation.b. acetylation.c. methylation.d. Any of the above can affect protein function.
During attenuation, when tryptophan levels are high, the ________ stem-loop forms and transcription _________ the trpL gene.a. 1–2, ends just pastb. 3–4, ends just pastc. 1–2, continues
The binding of _______ to lac repressor causes lac repressor to _______ to the operator site, thereby _______ transcription.a. glucose, bind, inhibitingb. allolactose, bind, inhibitingc. glucose, not
Which of the following combinations will cause the rate of transcription to increase?a. A repressor plus an inducerb. A repressor plus a corepressorc. An activator plus an inhibitord. None of the
For a riboswitch that controls transcription, the binding of a small molecule such as TPP controls whether the mRNAa. has an antiterminator or terminator stem-loop.b. has a Shine-Dalgarno
Translation can be regulated bya. translational repressors.b. antisense RNA.c. attenuation.d. both a and b.
When tryptophan binds to trp repressor, this causes trp repressor to __________ to the trp operator and ________ transcription.a. bind, inhibitb. not bind, inhibitc. bind, activated. not bind,
What is an operon?a. A site in the DNA where a regulatory protein bindsb. A group of genes under the control of a single promoterc. An mRNA that encodes several genesd. All of the above are true of
A repressor is a __________ that _________ transcription.a. small effector molecule, inhibitsb. small effector molecule, enhancesc. regulatory protein, inhibitsd. regulatory protein, enhances
What is the genetic code?a. The relationship between a three-base codon sequence and an amino acid or the end of translationb. The entire base sequence of an mRNA moleculec. The entire sequence from
Let’s suppose a researcher mixed together nucleotides with the following percentages of bases: 30% G, 30% C, and 40% A. If RNA was made via polynucleotide phosphorylase, what percentage of the
If a tRNA has an anticodon with the sequence 3′-GAC-5′, which amino acid does it carry?a. Aspartic acidc. Leucineb. Valined. Glutamine
Each ribosomal subunit is composed ofa. multiple proteins.c. tRNA.b. rRNA.d. both a and b.
During the initiation stage of translation in bacteria, which of the following events occur(s)?a. IF1 and IF3 bind to the 30S subunit.b. The mRNA binds to the 30S subunit, and tRNAfMet binds to the
An inborn error of metabolism is caused bya. a mutation in a gene that causes an enzyme to be inactive.b. a mutation in a gene that occurs in somatic cells.c. the consumption of foods that disrupt
The reading frame begins with a _____________ and is read ____________________.a. promoter, one base at a timeb. promoter, in groups of three basesc. start codon, one base at a timed. start codon, in
In the triplet-binding assay carried out by Nirenberg and Leder, an RNA triplet composed of three bases was able to cause thea. translation of a polypeptide.b. binding of a tRNA carrying the
The anticodon of a tRNA is located in thea. 3′ single-stranded region of the acceptor stem.b. loop of the first stem-loop.c. loop of the second stem-loop.d. loop of the third stem-loop.
The site(s) on a ribosome where tRNA molecules may be located includea. the A site.c. the E site.b. the P site.d. all of the above.
Kozak rules determinea. the choice of the start codon in complex eukaryotes.b. the choice of the start codon in bacteria.c. the site in the mRNA where translation ends.d. how fast the mRNA is
The reason why Beadle and Tatum observed four different categories of mutants that could not grow on media without methionine is becausea. the enzyme involved in methionine biosynthesis is composed
The fourth codon in an mRNA is GGG, which specifies glycine. Assuming that no amino acids are removed from the polypeptide, which of the following statements is correct?a. The third amino acid from
An enzyme known as __________ attaches an amino acid to the __________ of a tRNA, thereby producing __________.a. aminoacyl-tRNA synthetase, anticodon, a charged tRNAb. aminoacyl-tRNA synthetase,
During the peptidyl transfer reaction, the polypeptide, which is attached to a tRNA in the __________, becomes bound via ________ to an amino acid attached to a tRNA in the __________.a. A site,
A type of secondary structure found in proteins isa. an α helix.b. a β sheet.c. Both a and b are secondary structures in proteins.d. Neither a nor b is a secondary structure in proteins.
A uracil-rich sequence occurs at the end of the RNA ina. ρ-dependent termination.c. both a and b.b. ρ-independent termination.d. none of the above.
With regard to transcriptional termination in eukaryotes, which model(s) suggest(s) that RNA polymerase is physically removed from the DNA?a. Allosteric modelc. Both modelsb. Torpedo modeld. Neither
Which of the following is a function of the 7-methylguanosine cap?a. Exit of mRNA from the nucleusb. Efficient splicing of pre-mRNAc. Initiation of translationd. All of the above are functions of the
Sigma (σ) factor is needed during which stage(s) of transcription?a. Initiationc. Terminationb. Elongationd. All of the above
The basal transcription apparatus is composed ofa. five general transcription factors.b. RNA polymerase II.c. a DNA sequence containing a TATA box and transcriptional start site.d. all of the above.
Which of the following statements about a spliceosome is false?a. A spliceosome splices pre-mRNA molecules.b. A spliceosome removes exons from RNA molecules.c. A spliceosome is composed of snRNPs.d.
The three stages of transcription area. initiation, ribosome binding, and termination.b. elongation, ribosome binding, and termination.c. initiation, elongation, and termination.d. initiation,
For the following five sequences, what is the consensus sequence?5′–GGGAGCG–3′5′–GAGAGCG–3′5′–GAGTGCG–3′5′–GAGAACG–3′5′–GAGAGCA–3′a. 5′–GGGAGCG–3′b.
An enhancer is a _____________ that ___________ the rate of transcription.a. trans-acting factor, increasesb. trans-acting factor, decreasesc. cis-acting element, increasesd. cis-acting element,
A ribozyme isa. a complex between RNA and a protein.b. an RNA that encodes a protein that functions as an enzyme.c. an RNA molecule with catalytic function.d. a protein that degrades RNA molecules.
Which of the following base sequences is used during transcription?a. Promoter and terminatorb. Start and stop codonsc. Ribosome-binding sited. Both a and b
Within a promoter, a transcriptional start site isa. located at the −35 sequence and is recognized by σ factor.b. located at the −35 sequence and is where the first base is used as a template
Which RNA polymerase in eukaryotes is responsible for the transcription of genes that encode proteins?a. RNA polymerase Ib. RNA polymerase IIc. RNA polymerase IIId. All of the above transcribe
Which of the following are examples of RNA modifications?a. Splicingb. Capping with 7-methylguanosinec. Adding a polyA taild. All of the above are examples of RNA modifications.
Which of the following is not a key difference between bacteria and eukaryotes?a. Initiation of transcription requires more proteins in eukaryotes.b. A 7-methylguanosine cap is added only to
To make a new DNA strand, which of the following is/are necessary?a. A template strandc. Heavy nitrogenb. Nucleotidesd. Both a and b
The model that correctly describes the process of DNA replication isa. the conservative model.b. the semiconservative model.c. the dispersive model.d. All of the above models describe the process

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