Sapling Homework
Which of the following statements about the genetic code are most accurate? Select all that apply. A: The genetic code is generally non-overlapping. B: An initiation codon sets the reading frame. C: The genetic code is generally overlapping. D: Three initiation codons set the three possible reading frames. E: The promoter sets the reading frame.
A: The genetic code is generally non-overlapping. B: An initiation codon sets the reading frame.
Which of the following is the first step of translation elongation? A: The small and large ribosomal subunits combine with mRNA and the tRNA carrying methionine. B: A peptide bond is formed between the amino acids attached to the tRNAs in the P and A sites. C: A charged tRNA binds to the A site. D: The ribosome translocates down the mRNA in the 5\' -> ʹ→3\'ʹ direction. E: The mRNA attaches to the small ribosomal subunit.
C: A charged tRNA binds to the A site.
How is the transcription start site determined in bacteria? A: By the presence of a DNA bubble B: By the binding of the first primer C: By the binding of RNA polymerase to the consensus sequences of the promoter D: By the presence of the TATA box E: By the presence of an enhancer element
C: By the binding of RNA polymerase to the consensus sequences of the promoter
What are CpG islands? A: DNA regions that remove acetyl groups from histone tails B: DNA regions with many cytosine-guanine base pairs C: DNA regions with many cytosine bases adjacent to guanine bases D: DNA regions that are the sites of X inactivation in male mammals E: DNA regions that form complexes with acetylase proteins
C: DNA regions with many cytosine bases adjacent to guanine bases
During the rho-independent termination of transcription in some bacteria, the formation of ___________ is critical. A: A Rut site B: A terminator sequence C: An RNA-DNA duplex D: A hairpin loop via inverted repeats E: A Rho enzyme
D: A hairpin loop via inverted repeats
Frequently, important DNA regions with specific functions tend to contain short stretches of nucleotides that are conserved across different organisms (e.g., promoter sequence) and are recognized by specific proteins. What are these conserved sequences called? A: Initiators B: Critical elements C: Codons D: Repetitive sequences E: Consensus sequences
E: Consensus sequences
How are siRNAs and miRNAs made? A: RISC complexes process and cleave double-stranded RNA to produce 21- to 25-nucleotide-long sequences. B: Slicer processes and cleaves double-stranded RNA to produce 21- to 25-nucleotide-long sequences. C: Dicer processes and cleaves double-stranded RNA to produce 21- to 25-nucleotide-long sequences. D: RNA polymerase methylates RNA, tagging it for cleavage into miRNA and siRNA. E: RNA polymerase transcribes siRNAs and miRNAs individually based on cellular stimuli.
C: Dicer processes and cleaves double-stranded RNA to produce 21- to 25-nucleotide-long sequences.
To which part of the mRNA sequence does the RISC bind? A: poly(A) tail B: stop codon C: 3' UTR D: start codon E: 5' UTR
C: 3' UTR
Proteins are composed of ______ linked together by _______ bonds. A: Amino acids; peptide B: Genes' phosphodiester C: Nucleic acids; phosphodiester D: enzymes; peptide E: RNA; hydrogen
A: Amino acids; peptide
Which nucleotide base is methylated in DNA methylation? A: Cytosine B: Adenine C: Uracil D: Guanine E: Thymine
A: Cytosine
Which of the following genes are specifically transcribed by eukaryotic RNA polymerase II? A: Pre-mRNA B: Large rRNA C: crRNA D: tRNA E: Small rRNA
A: Pre-mRNA
Which of the following statements about RNA is not true? A: RNA is a more stable molecule than DNA B: Uracil is found in RNA as one of the two pyrimidine nitrogenous bases C: RNA typically consists of a single polynucleotide strand with distinct secondary structures. D: RNA is thought to have dominated early life on earth, serving as both genetic information and as a catalyst. E: RNA possesses catalytic activity, which earned it the name "ribozyme."
A: RNA is a more stable molecule than DNA
Which of the following normally happens in the regulation of the trp operon when high levels of tryptophan are present? A: Regions 3 and 4 will pair in the attenuation region in the 5′\' UTR of the RNA. B: Regions 2 and 3 will pair in the attenuation region in the 5\'′ UTR of the RNA. C: The trp activator protein will be produced. D: The trp repressor will become inactivated. E: Regions 2 and 4 will pair in the attenuation region in the 5′\' UTR of the RNA.
A: Regions 3 and 4 will pair in the attenuation region in the 5′\' UTR of the RNA.
Which of the following is not a characteristic of transcriptional activator proteins? A: They are capable of binding DNA at a consensus sequence in the protein-coding part of the gene. B: They can interact with other components of the transcriptional apparatus. C: They are capable of binding DNA at a consensus sequence of a regulatory promoter. D: They contain one or more DNA-binding motifs. E: They can influence the rate of transcription.
A: They are capable of binding DNA at a consensus sequence in the protein-coding part of the gene.
Which of the following contains the TATA-binding protein (TBP)? A: Transcription factor TFIID B: Sigma subunit C: Bacterial RNA polymerase D: Rut enzyme E: Rho complex
A: Transcription factor TFIID
What types of proteins recognize and bind to eukaryotic upstream regulatory promoter consensus sequences? A: Transcriptional activator proteins B: RNA polymerase III C: Rut proteins D: Sigma subunits E: All of these proteins can bind to the regulatory promotor sequences
A: Transcriptional activator proteins
What is the basal transcription apparatus? A: a complex of RNA polymerase, transcription factors, and other transcription proteins B: a complex of DNA polymerase, TATA boxes, and the DNA sequence C: a complex of RNA polymerase, translation factors, and other translation proteins D: a complex of RNA polymerase, core promoters, and regulatory promoters E: a complex of DNA polymerase, transcription factors, and other transcription proteins
A: a complex of RNA polymerase, transcription factors, and other transcription proteins
What is the regulatory segment of an mRNA that binds a small molecule resulting in a change in the production of the protein encoded by this mRNA called? A: a riboswitch B: a promotor C: an attenuator D: an activator E: a repressor
A: a riboswitch
Proteins that change shape on binding to another molecule are called ____. A: allosteric proteins B: inducible proteins C: activator proteins D: antisense proteins E: structural proteins
A: allosteric proteins
A system of gene control in bacterial operons in which glucose is used preferentially and the metabolism of other sugars is repressed in the presence of glucose is called _____. A: catabolite repression B: coordinate induction C: antisense regulation D: attenuation E: negative control
A: catabolite repression
Which of the following are mechanisms of mRNA surveillance? Select all that apply. A: nonstop mRNA decay B: no-go decay C: premature-termination mediation D: tRNA mediated mRNA decay E: nonsense-medicated mRNA decay
A: nonstop mRNA decay B: no-go decay E: nonsense-medicated mRNA decay
The termination of translation requires which of the following? Select all that apply. A: release factors B: stop codon on the mRNA C: E site of the ribosomal complex D: terminator tRNA E: GTP
A: release factors B: stop codon on the mRNA E: GTP
Which component of translation is frequently targeted by antibiotics? A: the ribosome B: IF-2 C: the template mRNA D: tRNAs E: aminoacyl-tRNA synthestase
A: the ribosome
Which of the following is not a mechanism of action of RNA inference? A: ubiquitination of proteins B: inhibition of translation C: cleavage of mRNA D: transcriptional silencing E: degradation of mRNA
A: ubiquitination of proteins
Which of the following is a feature of both prokaryotic and eukaryotic genes? A: DNA must be unwound from histone proteins before transcription of a gene takes place. B: DNA-binding proteins influence the ability of RNA polymerase to initiate transcription of a gene. C: Genes are organized into operons. D: The nuclear membrane separates gene transcription and translation. E: One promoter controls a cluster of genes.
B: DNA-binding proteins influence the ability of RNA polymerase to initiate transcription of a gene.
Which statement is most consistent with the one gene, one enzyme hypothesis originally proposed by Beadle and Tatum? A: A gene can only make one enzyme in a cell cycle B: Every gene encodes a separate enzyme C: Genes and enzymes are important D: Every enzyme makes on gene E: A gene can only make one enzyme in a cell cycle
B: Every gene encodes a separate enzyme
In eukaryotic cells, promoter consensus sequences are recognized by accessory proteins that recruit a specific RNA polymerase. Which of the following types of accessory proteins serve this purpose? A: Enhancer B: General transcription factors C: Transcription activators D: Transcription repressors E: Single-strand-binding proteins
B: General transcription factors
The way that proteins fold into beta pleated sheets and alpha helices is dependent on their _____. A: Peptide bonds B: Primary structure C: Quaternary structure D: Tertiary structure E: Secondary structure
B: Primary structure
Most bacterial RNA polymerases are made up of five subunits that have distinct functions for transcription. Which of the following subunits does not permanently associate with the enzyme core? A: Beta prime B: Sigma C: Alpha D: Omega E: Beta
B: Sigma
Which of the following statements is not true about repressors in eukaryotic cells? A: They can interfere with the assembly of the basal transcription apparatus. B: They directly block RNA polymerase. C: They can bind near an activator site and prevent activator contact with the basal transcription apparatus. D: They bind to silencer sequences. E: They can compete with activators for DNA-binding sites.
B: They directly block RNA polymerase
The type of transcriptional control in operons in which a regulatory protein is an activator and stimulates transcription is called _____. A: induction B: positive control C: repression D: negative control E: attenuation
B: positive control
What is the function of lacI in the regulation of the lac operon? A: It encodes a repressor that, in the presence of lactose, binds to the lac operator and blocks expression of the structural genes. B: It is the operator that mediates the transcription of the structural genes. C: It encodes a repressor that, in the absence of lactose, binds to the lac operator and blocks expression of the structural genes. D: It is a structural gene that encodes permease. E: It is the promoter that mediates the transcription of the operon.
C: It encodes a repressor that, in the absence of lactose, binds to the lac operator and blocks expression of the structural genes.
What is the function of the lac operator? A: It produces an initiator RNA molecule B: It produces the lac repressor protein C: It is bound by the lac repressor protein D: It binds RNA polymerase E: It binds lactose
C: It is bound by the lac repressor protein
The diagram below represents a transcription unit comprised of three critical regions, the promoter, the coding region, and the terminator. Which region would not be present in the final RNA transcript? A: All three regions are transcribed into RNA B: Terminator C: Promoter D: Coding region
C: Promoter
A small RNA that can base pair with an mRNA molecule and affects its functioning is called _____. A: a repressor B: a riboswitch C: an antisense RNA D: an inducer E: an activator
C: an antisense RNA
A mechanism of genetic regulation in which the synthesis of a short RNA is terminated before the structural genes of the operon can be transcribed is called_________. A: repression B: positive control C: attenuation D: negative control E: induction
C: attenuation
Which of the following RNA types is found only in prokaryotes? A: rRNA B: mRNA C: crRNA D: snRNA E: tRNA
C: crRNA
A mutation in the lac promoter region that causes this region to no longer function would lead to which of the following? A: enhanced initiation of transcription of the structural genes B: expression of the lac structural genes in the absence of lactose C: lack of expression of the lac structural genes in the presence of lactose D: expression of the lac structural genes in the presence of lactose E: overexpression of the lac structural genes
C: lack of expression of the lac structural genes in the presence of lactose
Which of the following classes of RNA serves as the coding instruction read by the ribosome to produce a polypeptide chain? A: tRNA B: miRNA C: mRNA D: rRNA E: snRNA
C: mRNA
The bacterial transfer-messenger RNA system _____. A: generates truncated proteins B: mediated the interaction of tRNAs with mRNA C: removes stalled ribosomes in bacteria D: restores normal translation of the gene by a stalled ribosome E: directly targets the mRNA with a stalled ribosome for degradation
C: removes stalled ribosomes in bacteria
What are insulators? A: DNA sequences that block the effect of enhancers in an orientation-dependent manner B: proteins that enhance the effect of enhancers in a position-dependent manner C: proteins that block the effect of enhancers in a position-dependent manner D: DNA sequences that block the effect of enhancers in a position-dependent manner E: DNA sequences that block the effect of enhancers in a position-independent manner
D: DNA sequences that block the effect of enhancers in a position-dependent manner
The discovery that some proteins are composed of more than one polypeptide chain and that different polypeptide chains are encoded by separate genes became the _____. A: Research that revealed the process of translation B: Many genes, many polypeptides hypothesis C: One protein, one polypeptide hypothesis D: One gene, one polypeptide hypothesis E: One gene, one enzyme hypothesis
D: One gene, one polypeptide hypothesis
Which of the following statements about the process of transcription in archaea is the most accurate? A: Transcription in archaea is very similar to transcription in both bacteria and eukaryotes. B: Transcription in archaea is most similar to that in bacteria. C: Transcription in archaea has no common elements with transcription in either bacteria or eukaryotes. D: Transcription in archaea is most similar to that in eukaryotes.
D: Transcription in archaea is most similar to that in eukaryotes.
What is the role of tryptophan in the regulation of the trp operon? A: When tryptophan levels are low, tryptophan stimulates the transcription of the structural genes. B: When tryptophan levels are high, tryptophan binds to RNA polymerase to stimulate transcription. C: When tryptophan levels are high, tryptophan stimulates the transcription of the trp regulatory gene. D: When tryptophan levels are high, tryptophan binds to the inactive trp repressor, making it active. E: When tryptophan levels are low, tryptophan inactivates the trp repressor.
D: When tryptophan levels are high, tryptophan binds to the inactive trp repressor, making it active.
Which of the following matches the modification of histones with the correct effect on the histone? A: deacetylation of histones by deacetylase—-stimulates transcription B: acetylation of histones by acetyltransferase-—represses transcription C: methylation of H3K4-—represses transcription D: acetylation of histones-—stimulates transcription E: methylation of histones—-stimulates replication
D: acetylation of histones-—stimulates transcription
Which of the following is the true inducer of the lac operon? A: galactose B: cAMP C: lactose D: allolactose E: glucose
D: allolactose
Which of the following sets of conditions will lead to the highest expression of the lac structural genes? A: low levels of lactose and low levels of glucose B: high levels of the lac repressor and high levels of glucose C: low levels of lactose and high levels of glucose D: high levels of lactose and low levels of glucose E: high levels of lactose and high levels of glucose
D: high levels of lactose and low levels of glucose
Aminoacyl-tRNA synthetases recognize their specific amino acid by _____ and recognize the tRNAs that carry it by the _____. A: size, charge, and R group; acceptor stem B: size, charge, and R group; TΨ C arm C: nucleotide sequence; anticodon D: size, charge, and R group; nucleotide sequence E: nucleotide sequence; size, charge, and R group
D: size, charge, and R group; nucleotide sequence
Which of the following RNA types is found only in eukaryotes? A: crRNA B: mRNA C: tRNA D: snoRNA E: rRNA
D: snoRNA
Which of the following is not involved in the initiation of translation in bacteria? A: small and large ribosomal subunits B: mRNA C: tRNA carrying N-formylmethinoine that will occupy the P site D: tRNA carrying the next amino acid that will occupy the A site E: GTP and initiation factors
D: tRNA carrying the next amino acid that will occupy the A site
Whereas bacterial cells typically possess only one type of RNA polymerase, most eukaryotic cells possess _____ distinct types of RNA polymerase. A: 4 B: 7 C: 2 D: 12 E: 3
E: 3
There are 64 codons, 20 different amino acids, and approximately 30-50 tRNAs. Which of the following statements does not help explain these numbers? A: Flexibility, or wobble, between the anticodon and the codon allows one tRNA to pair with multiple codons. B: Isoaccepting tRNAs can carry the same amino acid. C: Many amino acids are coded for by more than one of the 61 sense codons. D: Synonymous codons code for the same amino acid. E: The 3\' base of the anticodon on the tRNA can pair weakly with the 5\'ʹ codon base.
E: The 3\' base of the anticodon on the tRNA can pair weakly with the 5\'ʹ codon base.
Why are transcriptional regulator proteins necessary? A: The basal transcription apparatus will repress transcription without them. B: The basal transcription apparatus will not bind to the promoter without them. C: The transcriptional regulator proteins will recruit RNA polymerases. D: The transcriptional regulator proteins keep the apparatus from being degraded by enzymes. E: The basal transcription apparatus can only produce minimal levels of transcription without them.
E: The basal transcription apparatus can only produce minimal levels of transcription without them.
How do response elements work to regulate transcription? A: They only function as a result of hormone signaling. B: They are transcriptional activators that increase transcription in response to stimuli. C: They are binding sites for transcriptional repressors in response to stimuli. D: They are specific to a certain gene and only respond to one stimulus. E: They are binding sites for transcriptional activators in response to stimuli.
E: They are binding sites for transcriptional activators in response to stimuli.
What is chromatin immunoprecipitation? A: a technique that determines where proteins are localized in the cell B: a technique that determines which strand of DNA is the template strand C: a technique that determines the sequence of the DNA in specific chromosomes D: a technique that determines how many chromosomes are in a cell E: a technique that determines the specific locations within the genome where proteins interact with DNA
E: a technique that determines the specific locations within the genome where proteins interact with DNA
Which of the following forms of gene regulation primarily occurs in eukaryotes? A: All of these forms of regulation occur equally in both prokaryotes and eukaryotes. B: regulation of translation C: regulation of mRNA stability D: regulation of transcription E: alteration of chromatin structure
E: alteration of chromatin structure
Which of the following is a common DNA-binding motif? A: iron-finger B: loop-helix-loop C: ring-loop-ring D: alanine zipper E: helix-turn-helix
E: helix-turn-helix
Which of the following is not a mechanism of gene regulation that can take place after transcription is completed in eukaryotes? A: RNA cleavage by siRNA B: mRNA degradation C: RNA splicing D: RNA interference E: polymerase stalling
E: polymerase stalling
When mRNAs are being translated simultaneously by multiple ribosomes, the structure is known as a(n) _____. A: polycistron B: polytene C: operon D: copolymer E: polyribosome
E: polyribosome
What is the first stage of protein synthesis? A: elongation, in which amino acids are joined to the polypeptide chain B: the assembly of transcription factors at the promoter C: initiation, in which the components necessary for translation are assembled at the ribosome D: setting the reading frame, where the initiation codon is recognized by RNA polymerase E: tRNA charging, in which the tRNAs bind to amino acids
E: tRNA charging, in which the tRNAs bind to amino acids
