Exam 2 (Chapter 9-12)
What is the maximum number of amino acids that can be specified by a codon consisting of a sequence of two bases? a. 4 b. 8 c. 16 d. 20
c. 16
Identify the component required for the chain initiation step of protein synthesis. a. DNA helicase b. Release factors c. 30S ribosomal subunit d. UAA
c. 30S ribosomal subunit
Which of the following sequences of DNA is most likely to form Z-DNA? a. 5'-ATCTACATCTACATAGATAT-3' 3'-TAGATGTAGATGTATCTATA-5' b. 5'-AAAAAAAAAAAAAAAAAAAA-3' 3'-TTTTTTTTTTTTTTTTTTTT-5' c. 5'-GCGCGCGCGCGCCGCGCGCG-3' 3'-CGCGCGCGCGCGCGCGCGCG-5' d. 5'-GGGGGGGGGGGGGGGGGGGG-3' 3'-CCCCCCCCCCCCCCCCCCCC-5'
c. 5'-GCGCGCGCGCGCCGCGCGCG-3' 3'-CGCGCGCGCGCGCGCGCGCG-5'
The mRNA must contain the following to allow for initiation of protein synthesis in E. coli. a. A purine rich sequence to bind to the ribosome. b. A pyrimidine rich sequence to bind to the ribosome. c. A Shine-Delgarno sequence. d. A purine rich sequence to bind to the ribosome and a Shine-Delgarno sequence. e. A pyrimidine rich sequence to bind to the ribosome and a Shine-Delgarno sequence.
c. A Shine-Delgarno sequence.
Explain the significance of a structural gene in the synthesis of proteins
A structural gene is a gene that directs the synthesis of a protein under the control of some regulatory gene. β-Galactosidase is coded for by a structural gene (lacZ). Also, structural genes encode the gene products that are involved in the biochemical pathway of the operon. Two structural genes—lacY and lacA—form a part of the operon. lacY encodes the enzyme lactose permease, whereas lacA encodes an enzyme called transacetylase.
Explain the mechanism of the action of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) in treating diseases.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are repetitive stretches of DNA found in archaea and bacteria. The sequences interact with CRISPR-associated proteins or Cas proteins. This combination is used by the bacteria as a protective mechanism against foreign DNA. The proteins are guided by a short strand of RNA to a specific DNA sequence to cut the DNA in two pieces. The bacteria take the RNA strand from the invading organism and use it to target the invader's DNA.
The human genome is though to have about how many genes? a. 10,000 b. 25,000 c. 50,000 d. 100,000 e. None of these is close to the estimate
b. 25,000
During elongation, tRNA binds initially to the a. "A" site on the ribosome. b. "P" site on the ribosome. c. "E" site on the ribosome.
a. "A" site on the ribosome.
RNA synthesis begins at the base in the DNA sequence designated by the following number: a. +1 (plus one) b. 0 (zero) c. −1 (minus one) d. −10 region (minus ten) e. It varies between genes.
a. +1 (plus one)
The human genome has 3 × 10^9 base pairs (bp) of DNA. If this were one continuous molecule and extended such that each nucleotide was separated from the adjacent nucleotide by 4 Å, as proposed in the Watson and Crick model, what would the end-to-end distance be? a. 1 meter b. 1 centimeter c. 1000 centimeters d. 1014 Å
a. 1 meter
At which position on tRNA is the wobble base of the triplet anticodon? a. 1st position (5' letter) b. 2nd position c. 3rd position (3' letter) d. Wobble can occur at any position
a. 1st position (5' letter)
Calculate the length/diameter ratio for the extended E. coli DNA (4 Å between adjacent nucleotides). E. coli DNA has 2 × 106 bp. a. 4 × 105 b. 1 × 105 c. 3 × 108 d. 3 × 106
a. 4 × 105
What provides the energy for rho-dependent chain termination? a. ATP hydrolysis distinct from any incorporation into the chain. b. Nucleotide hydrolysis associated with incorporation into the chain. c. Torsional stress built into the separating DNA strands. d. There is no energy requirement.
a. ATP hydrolysis distinct from any incorporation into the chain.
What is the start codon on the mRNA for prokaryotic translation? a. AUG b. UAA c. UAG d. UGA
a. AUG
Which of the following best describes the structure of a nucleosome? a. DNA wrapped around an octomer containing two each of H2A, H2B, H3, and H4 with H1 on the outside. b. DNA wrapped around an octomer of H1 with H2A,B, H3 & H4 on the outside. c. DNA wrapped around a octomer of either H2A/H2B or H3/H4 with H1 on the outside. d. DNA wrapped around a tetramer of either H2A/H2B or H3/H4 with H1 on the outside. e. None of these
a. DNA wrapped around an octomer containing two each of H2A, H2B, H3, and H4 with H1 on the outside.
How do enhancers differ from promoters? a. Enhancers do not bind RNA polymerase. b. Enhancers include the UP element. c. Enhancers bind the sigma (σ) factor. d. There is no difference; these terms are synonymous.
a. Enhancers do not bind RNA polymerase.
HIF-1 is related to which process? a. How we adapt to high altitude b. Pain tolerance c. Transcription attenuation d. all of these
a. How we adapt to high altitude
Which of the following is not true about RISC? a. It is only involved in cleaving dsRNA from viruses b. It is involved with processing of miRNA and siRNA c. It uses a protein from the argonaut family d. It unwinds dsRNA and eventually discards the passenger strand
a. It is only involved in cleaving dsRNA from viruses
What is the function of the sigma (σ) subunit of RNA polymerase in E. coli? a. It recognizes promoters where transcription should begin. b. It contains the active site for synthesis of RNA. c. It ensures proper processitvity of the polymerase, so it doesn't stop prematurely. d. It is involved in chain termination. e. It scrunches the DNA
a. It recognizes promoters where transcription should begin.
Which of the following statements concerning the B-form of DNA is false? a. It twists in a left-handed direction. b. The distance between base pairs is 3.4Å. c. The width of a base pair is about 1.1 nm. d. The diameter, including the phosphate, is about 20 Å.
a. It twists in a left-handed direction.
Which of the following is not a function of elongation factors in E. coli? a. Keep the ribosomal subunits bound together. b. Lead the incoming tRNA to its correct position on the ribosome. c. Carry GTP to provide energy for certain steps in the elongation process. d. Regenerate the elongation factors by replacing GTP for GDP. e. The elongation factors do all of these.
a. Keep the ribosomal subunits bound together.
Identify an amino acid that is coded by only one codon. a. Methionine b. Leucine c. Arginine d. Histidine
a. Methionine
Which of the following is not an advantage of degeneracy in the genetic code? a. More than one amino acid can bind to a tRNA. b. Each tRNA can bind to more than one codon. c. Most codons can bind to more than one tRNA. d. Fewer tRNA molecules are needed.
a. More than one amino acid can bind to a tRNA.
The hydrogen bonding interactions in a Watson-Crick AT base-pair involve what units in the adenine base? a. N-1 and the amino group on C-6 b. N-1 and N-3 c. N-7 and the amino group on C-6 d. N-7 and C-8
a. N-1 and the amino group on C-6
What distinguishes nucleotides from nucleosides? a. Nucleosides lack the phosphate group. b. Nucleosides lack the sugar group. c. Nucleosides lack a nitrogenous base. d. The two words are synonymous
a. Nucleosides lack the phosphate group.
Which of the following groups is not found in nucleosides? a. Phosphates b. Purines c. Pyrimidines d. Sugars e. All of these are found in nucleosides
a. Phosphates
Wobble allows each codon to interact with more than one tRNA. a. True b. False
a. True
Protein synthesis can occur while the mRNA molecule is being synthesized in: a. Prokaryotes only. b. Eukaryotes only. c. Unicellular organisms only. d. Multicellular organisms only. e. Plants but not animals
a. Prokaryotes only.
Which antibiotic confirmed that the growing peptide chain is transferred to the amino group of the incoming tRNA? a. Puromycin b. Streptomycin c. Cyclohexamide d. None of these antibiotics was useful for studying the mechanism of protein synthesis. e. None of these antibiotics actually interferes with peptide transfer.
a. Puromycin
Which of the following does not influence the timing of expression of an operon? a. Repressors b. Co-repressors c. Presence of substrates of the operon which need to be degraded d. Inducers e. All of these influence the timing of expression
a. Repressors
Which of the following statements is true for double-stranded DNA? a. The amount of A is the same as the amount of T, and the amount of G is the same as the amount of C. b. The amount of A is the same as the amount of G, and the amount of T is the same as the amount of C. c. The amount of A is the same as the amount of C, and the amount of G is the same as the amount of T. d. More than one of the above is true.
a. The amount of A is the same as the amount of T, and the amount of G is the same as the amount of C.
Which of the following is true concerning the first nucleotide incorporated into an RNA chain? a. The first nucleotide incorporated into the RNA chain retains its 5'-triphosphate b. The first nucleotide is always GMP c. The first nucleotide is always cleaved off post-transcriptionally d. The first nucleotide is always modified after transcription
a. The first nucleotide incorporated into the RNA chain retains its 5'-triphosphate
How do the core enzyme and the holoenzyme of RNA polymerase differ in E. coli? a. The holoenzyme includes the sigma (σ) subunit, the core enzyme does not. b. The core enzyme includes the sigma (σ) subunit, the holoenzyme does not. c. The holoenzyme transcribes from an RNA template, the core enzyme from a DNA template. d. The core enzyme transcribes from an RNA template, the holoenzyme from a DNA template
a. The holoenzyme includes the sigma (σ) subunit, the core enzyme does not.
How do eukaryotic ribosomes prevent false starts at inappropriate parts of the mRNA? a. There is a consensus sequence, called the Kozak sequence, surrounding the start codon in eukaryotes. b. The Shine-Dalgarno sequence positions the ribosome properly, just as in prokaryotes. c. Only one start codon ever appears in eukaryotic mRNA, so false starts are not a problem. d. Nothing; false starts are quite common in eukaryotic translation.
a. There is a consensus sequence, called the Kozak sequence, surrounding the start codon in eukaryotes.
Which of the following best describes leucine zipper motifs? a. They allow protein-protein interactions via hydrophobic bonds. b. They allow protein-protein interactions via hydrogen bonds. c. They allow protein-protein interactions via electrostatic interactions. d. They allow protein-DNA interactions by fitting into the major groove of DNA
a. They allow protein-protein interactions via hydrophobic bonds.
Which of the following is true about micro RNAs? a. They are a type of non-coding RNA b. They are a type of small interfering RNA c. They have been found only in simple organisms like roundworms d. All of these are true
a. They are a type of non-coding RNA
Transfer RNA molecules are characterized by all the following, except: a. They are one of the largest of the RNAs. b. Cloverleaf shape. c. Many modified bases. d. Extensive secondary and tertiary structure. e. All of these characterize transfer RNA molecules.
a. They are one of the largest of the RNAs.
16. Transfer RNAs contain an anti-codon loop meant to match (base pair) with a codon on an mRNA. a. True b. False
a. True
Alternative splicing of exons is a mechanism to get more than 1 protein from the same gene. a. True b. False
a. True
Attenuation mechanisms rely on alternative secondary structures forming in the mRNA. a. True b. False
a. True
Chaperones assist in protein folding by preventing aggregation of proteins before folding is completed. a. True b. False
a. True
Comparison of DNA sequences between widely diverse organisms indicates that all organisms have genetic similarity. a. True b. False
a. True
DNA binding domains are distinct from transcription-activation domains. a. True b. False
a. True
Inducers allow for a system in which an enzyme is not made unless it is needed. a. True b. False
a. True
Inducers for operons are often structurally related to the enzyme substrates of that operon. a. True b. False
a. True
Intracellular levels of cyclic AMP can affect the phosphorylation of proteins and enzymes as a secondary messenger. a. True b. False
a. True
The activating enzymes can actually remove wrong amino acids attached to a tRNA. a. True b. False
a. True
The actual functions of the factors in eukaryotes are similar to the functions of these factors in bacteria. a. True b. False
a. True
The amino acids are initially attached to either the 2' or 3' hydroxyl group of the tRNA. a. True b. False
a. True
The catabolite activator protein can overcome the effect of a repressor binding to the operon. a. True b. False
a. True
The initiation of eukaryotic translation can be a control point in overall gene expression? a. True b. False
a. True
The major difference between RNA initiation in eukaryotes and prokaryotes is the number of factors involved in the process. a. True b. False
a. True
The ribosome is actually a ribozyme. a. True b. False
a. True
The weakness of A−U base pairs at the end of the RNA molecule may help in dissociation of the new RNA product. a. True b. False
a. True
Under certain conditions, tRNAs can bind to the standard stop codons. a. True b. False
a. True
A polysome is a. a complex consisting of one mRNA to which several ribosomes are attached b. a polypeptide chain in the process of being formed c. an intermediate stage in the self-assembly of ribosomes d. an aggregate of ribosomal proteins
a. a complex consisting of one mRNA to which several ribosomes are attached
The template for protein synthesis is: a. a mRNA strand b. the DNA coding strand c. the DNA template strand d. a protein primer e. none of these
a. a mRNA strand
Aminoacyl-tRNA Synthetases are involved in which step of translation? a. activation b. initiation c. elongation d. termination e. none of these
a. activation
Which of the following is the most common modification of nucleic acid bases? a. addition of a methyl group b. addition of a carboxylic acid c. addition of a fluorine d. reduction of a carbonyl to an alcohol
a. addition of a methyl group
Which of the following nucleobases is a purine? a. adenine b. cytosine c. thymine d. uracil
a. adenine
The oligonucleotide AGGUCCAUUGAAp, is best described as a. an RNA oligonucleotide with a 3'phosphate b. an RNA oligonucleotide with a 5'phosphate c. a DNA oligonucleotide with a 3'phosphate d. a DNA oligonucleotide with a 5'phosphate
a. an RNA oligonucleotide with a 3'phosphate
Histones are proteins that a. are frequently associated with eukaryotic DNA b. are frequently associated with prokaryotic DNA c. are never found in association with DNA d. contain a high percentage of residues with carboxylic acid side chains e. None of these
a. are frequently associated with eukaryotic DNA
An aminoacyl-tRNA is initially bound to the ribosome a. at the A site on the 50S subunit b. at the P site on the 50S subunit c. at the A site on the 30S subunit d. at the P site on the 30S subunit
a. at the A site on the 50S subunit
In DNA structure, hydrophobic bonding via pi-clouds is referred to as a. base stacking. b. propeller twist. c. hyperchromicity. d. supercoiling. e. denaturation
a. base stacking.
Minor differences in the consensus sequence for RNA Polymerase a. can be exploited to vary the amount of mRNA which is synthesized from that gene. b. dictate the direction that RNA Polymerase proceeds from the promoter. c. dictate whether sigma (σ) factor is required. d. never occur. e. have no effect on transcription
a. can be exploited to vary the amount of mRNA which is synthesized from that gene.
During which phase do the β'- and σ-subunits of RNA polymerase melt 14 base pairs surrounding the transcription start site, causing the strands to separate? a. chain initiation b. chain elongation c. intrinsic chain termination d. rho-dependent chain termination
a. chain initiation
The formylation of methionine in prokaryotes a. depends on two different tRNAs, where methionine can be formylated when bound to one form and not the other. b. depends on two different tRNAs, where methionine can be formylated when bound to either one. c. depends on one tRNA, where methionine is formylated after binding. d. takes place before methionine is bound to tRNA
a. depends on two different tRNAs, where methionine can be formylated when bound to one form and not the other.
In bacteria, translation of the mRNA begins a. during the synthesis of the mRNA. b. after synthesis of the mRNA has been completed. c. after 5' capping of the mRNA. d. after all processing (capping, polyadenylation, and removal of introns) has taken place
a. during the synthesis of the mRNA.
Leader sequences for protein transport to specific organelles are removed by proteases associated with the: a. endoplasmic reticulum b. golgi apparatus c. nucleus d. mitochondra e. none of these
a. endoplasmic reticulum
RNA polymerases from prokaryotes and eukaryotes a. have sequence homology in catalytic subunits b. have identical σ factors c. differ because there is no analogue to the prokaryotic α subunit in eukaryotes d. have the same number and kind of subunits
a. have sequence homology in catalytic subunits
The enzyme principally responsible for RNA synthesis in Escherichia coli a. is a multisubunit enzyme b. consists of a single polypeptide chain c. requires Mn2+ for activity d. requires a DNA primer
a. is a multisubunit enzyme
RNA transcribed from the coding strand instead of the template strand a. is called antisense RNA. b. produces histones. c. is tRNA. d. never occurs
a. is called antisense RNA.
Which of the following RNAs is the least abundant in a typical cell? a. mRNA b. rRNA c. snRNA d. tRNA
a. mRNA
Proteins that recognize DNA with specific base sequences are a. more likely to bind to the major groove. b. more likely to bind to the minor groove. c. equally likely to bind to the major or minor grooves. d. never occur
a. more likely to bind to the major groove.
Capping of eukaryotic mRNA a. occurs at the 5' end. b. occurs at the 3' end. c. occurs at both ends. d. doesn't occur at all.
a. occurs at the 5' end.
Cytosine is a(n) _____ nitrogenous aromatic compound. a. one-ring b. two-ring c. four-ring d. six-ring
a. one-ring
The nucleotide sequence of DNA is which level of structure? a. primary b. secondary c. tertiary d. quaternary
a. primary
Activation of amino acids a. produces a pyrophosphate byproduct. b. produces an inorganic phosphate. c. produces a cyclic AMP. d. does not involve the release of energy
a. produces a pyrophosphate byproduct.
The elongation and termination phases of eukaryotic transcription a. require several protein factors b. are better understood than the initiation phase c. are not subject to control mechanisms, only the initiation phase d. proceed at a constant rate and always stop at the same termination sequence
a. require several protein factors
The eukaryotic TATA-binding protein (TBP) functions in a manner similar to a. sigma (σ) factor in E. coli. b. rho (ρ) factor in E. coli. c. lac I in E. coli. d. CAP in E. coli.
a. sigma (σ) factor in E. coli.
A commonly encountered feature of transfer RNA synthesis is a. the precursor of several tRNA molecules is transcribed in one long polynucleotide sequence b. there is little or no base modification after transcription c. modification of the sugar moiety never takes place d. the covalent binding of tRNA to specific proteins
a. the precursor of several tRNA molecules is transcribed in one long polynucleotide sequence
In the wobble phenomenon, the base that wobbles is found in a. the tRNA. b. the mRNA c. either the tRNA or the mRNA.
a. the tRNA.
Cyclic AMP affects transcription by a. triggering the action of several protein factors b. phosphorylating a subunit of RNA polymerase c. phosphorylating a transcription factor d. inhibiting DNA looping e. None of these
a. triggering the action of several protein factors
A single operon a. usually contains all the enzymes which are specific for the synthesis of a special biomolecule. b. usually does not contain all the enzymes which are specific for the synthesis of a special biomolecule. c. usually contains only a single structural gene for a critical enzyme. d. usually contains only a gene for a repressor
a. usually contains all the enzymes which are specific for the synthesis of a special biomolecule.
The first tRNA (bearing fmet) binds to the a. "A" site of the ribosome. b. "P" site on the ribosome. c. "E" site on the ribosome
b. "P" site on the ribosome.
The outside diameter of a piece of DNA is closest to a. 2 Å. b. 20 Å. c. 200 Å. d. 2000 Å
b. 20 Å.
tRNAmet and tRNAfmet contain a sequence _____ that pairs with the sequence 5'-AUG-3' in the mRNA sequence . a. 5'-UAC-3' b. 3'-UAC-5' c. 5'-CAU-3' d. 3'-CAU-5'
b. 3'-UAC-5'
Which piece of DNA will have the higher Tm, one with a cytosine plus guanine content of 30% or one with a cytosine plus guanine content of 50% if both are heated under the same experimental conditions? a. 30% cytosine plus guanine will have the higher Tm. b. 50% cytosine plus guanine will have the higher Tm. c. Their Tm's will be the same. d. There's no way to predict for this information.
b. 50% cytosine plus guanine will have the higher Tm.
Which of the following offers the best description of a Pribnow box? a. A promoter consensus sequence located at approximately −35. b. A promoter consensus sequence located at approximately −10. c. A sequence forming a hairpin loop signaling the termination of transcription. d. A sequence immediately surrounding the start site of transcription.
b. A promoter consensus sequence located at approximately −10.
Which of following best describes the two-step process for adding amino acids to tRNAs? AA = amino acid, Pi = phosphate, PPi = pyrophosphate a. AA + ATP → AA−P + ADP; AA−P + tRNA → AA−tRNA + Pi b. AA + ATP → AA−AMP + PPi ; AA−AMP + tRNA → AA−tRNA + AMP c. tRNA + ATP → tRNA−P + ADP; tRNA−P + AA → AA−tRNA + Pi d. tRNA + ATP → tRNA−AMP + PPi ; tRNA−AMP + AA → AA−tRNA + AMP
b. AA + ATP → AA−AMP + PPi ; AA−AMP + tRNA → AA−tRNA + AMP
Which of the following is not a common modification occurring after polymerization of RNA? a. Methylation of bases. b. Addition of phosphate to the bases. c. Removal of bases from the polymer. d. Addition of bases to the polymer. e. All of these changes are common.
b. Addition of phosphate to the bases.
At what point does the formylation reaction take place to produce N-formylmethionine? a. On the free amino acid prior to its addition to a tRNA. b. After methionine has been added to a specific tRNA. c. After the methionine-tRNA adduct has complexed with the ribosome. d. After the first peptide bond is formed on the ribosome
b. After methionine has been added to a specific tRNA.
At what point does the sigma (σ) subunit of RNA polymerase released from the core enzyme? a. Prior to the incorporation of any nucleotides into an RNA strand. b. After transcription begins and about 10 nucleotides have been added to the RNA chain. c. Just prior to chain termination. d. Never; it is an intrinsic part of the core enzyme. e. After RNA polymerase discovers an inverted repeat
b. After transcription begins and about 10 nucleotides have been added to the RNA chain.
Which is the dominant form of DNA found in the cell? a. A b. B c. Z d. H e. All forms of DNA are found in equal amounts
b. B
Which of following statements describes a difference between replication of DNA and transcription of RNA? a. Nucleoside triphosphates are the precursors for replication, but nucleoside diphosphates are used for transcription. b. Both strands of DNA are copied in replication, but usually only one is copied in transcription. c. Base pairing is used to copy the sequence in replication, but not in transcription. d. The chain grows from the 5' to the 3' end in replication, but 3' to 5' in transcription. e. None of these
b. Both strands of DNA are copied in replication, but usually only one is copied in transcription.
Which of these terms does not describe the DNA strand used to direct RNA synthesis? a. Template strand b. Coding strand c. Antisense strand d. Negative or "−" strand e. All these terms describe the DNA strand used to direct RNA synthesis
b. Coding strand
Which of the following correctly describes a difference between RNA & DNA polymerases? a. RNA polymerases usually do not need a template, while DNA polymerases do. b. DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not. c. RNA polymerases usually synthesize introns, while DNA polymerases synthesize cistrons. d. RNA polymerases polymerize 5' → 3', while DNA polymerases polymerize 3' → 5'. e. None of these
b. DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not.
Which of the following is not a prokaryotic elongation factor? a. EF-Tu b. EF-Ts c. EF-G d. EF-P e. all of these are prokaryotic elognation factors
b. EF-Ts
How do eukaryotic and prokaryotic translation compare? a. There is little to no difference between them; all the factors are homologous. b. Eukaryotes utilize very different protein factors during the process but the ribosomes are homologous. c. Eukaryotic ribosomes are very different, but the protein factors used during the process are homologous. d. Both eukaryotic ribosomes and the protein factors used during the process are very different.
b. Eukaryotes utilize very different protein factors during the process but the ribosomes are homologous.
Which of the following statements about eukaryotic and prokaryotic RNA polymerases, is false? a. There are 3 different RNA polymerases in eukaryotes, instead of just one. b. Eukaryotic polymerases have the same number of subunits as prokaryotic ones. c. Only prokaryotic polymerases use sigma factor. d. The enzymatic mechanism is the same for both types of organisms.
b. Eukaryotic polymerases have the same number of subunits as prokaryotic ones.
Each tRNA molecule has a separate activating enzyme. a. True b. False
b. False
In bacteria, each mRNA will bind to only one ribosome at a time. a. True b. False
b. False
Post-transcription processing of mRNA in prokaryotes is required. a. True b. False
b. False
Specificity of aminoacyl-tRNA synthetases is always based on the anticodon. a. True b. False
b. False
The end of the new mRNA molecule in E. coli. usually terminates in a string of A's a. True b. False
b. False
The leucine zipper is different from other DNA binding domains, since it requires the DNA-binding protein to form a dimer. a. True b. False
b. False
There is only one sigma subunit, since the same RNA Polymerase must bind to all genes in E. coli. a. True b. False
b. False
Wobble allows a single codon to code for more than one amino acid. a. True b. False
b. False
Which of the following is true concerning protein synthesis and memory? a. Animals that cannot make new proteins have no memories b. Inhibition of protein synthesis in eukaryotes leads to lack of long term memory c. Production of CREB is inhibited when strong memories are made d. none of these is true
b. Inhibition of protein synthesis in eukaryotes leads to lack of long term memory
Which of the following is not a key advantage of wobble in the codon-anticodon reaction? a. It allows for fewer tRNAs in the cell. b. It allows for making more than one protein from the same coding sequence. c. It allows for a certain amount of mutation in the mRNA without affecting the protein sequence. d. All of these are advantages of wobble.
b. It allows for making more than one protein from the same coding sequence.
Which of the following is not a function of initiation factors in E. coli? a. Prevent the ribosomal subunits from binding together. b. Lead the initial tRNA to its correct position on the large subunit of the ribosome. c. Help the mRNA to bind to the tRNA. d. Carry GTP to provide energy for certain steps in the initiation process. e. The initiation factors do all of these.
b. Lead the initial tRNA to its correct position on the large subunit of the ribosome.
The most recent discoveries in RNA research are: a. mRNA and tRNA b. MiRNA and SiRNA c. snRNA and snurps d. tRNA and MiRNA
b. MiRNA and SiRNA
Which of the following is not true? a. The amount of UV absorbance increases, but the wavelength does not change as DNA nears its melting point b. Once DNA is denatured, it cannot renature c. The melting temperature partially depends on the GC content d. The nature of the solvent the DNA is in can affect the melting temperature
b. Once DNA is denatured, it cannot renature
Which of the following is not true concerning silent mutations? a. Silent mutations refer to base sequence differences that do not change the amino acid coded for b. Only changes in base sequence that lead to a different amino acid can have an effect on the organism c. Changes in the sequence of an exonic splicing enhancers can lead faulty removal of introns d. Silent mutations in a gene for pain tolerance has been correlated with human differences in perception of pain
b. Only changes in base sequence that lead to a different amino acid can have an effect on the organism
There is no codon for the amino acid hydroxyproline, but this amino acid is a prominent feature of collagen structure. Which of the following is a likely explanation? a. Hydroxyproline is substituted for proline after translation by a cut and patch mechanism. b. Proline is covalently modified to give hydroxyproline after translation. c. There is an alternative mechanism for synthesis of proteins that contain hydroxyproline. d. It is not possible to form a hypothesis from the information given.
b. Proline is covalently modified to give hydroxyproline after translation.
Which of following statements concerning RNA transcription is false? a. The DNA strands become separated during synthesis. b. Synthesis of RNA is as accurate as synthesis of DNA c. The template strand is read in the 3' → 5' direction. d. All 4 ribonucleotides are required. e. A primer is required for RNA synthesis
b. Synthesis of RNA is as accurate as synthesis of DNA
The Tm for melting the double helix is: a. The temperature at which the helix starts to open. b. The midpoint of the range over which the helix denatures. c. The temperature at which the helix is completely open. d. The energy needed to melt the DNA. e. None of these is correct.
b. The midpoint of the range over which the helix denatures.
What is the need for a primer in transcription? a. It ensures the fidelity of the newly synthesized RNA strand. b. There is none. c. RNA polymerases requires a preexisting strand with a nucleotide having a 3'−OH. d. RNA polymerase requires a preexisting strand with a nucleotide having a 5'−OH.
b. There is none.
Which best describes the relationship between the nucleobases in a piece of DNA? a. They are parallel to the helical axis. b. They are perpendicular to the helical axis. c. They are randomly oriented with respect to the helical axis. d. They are covalently bonded between the nucleobases across from one anothr in the two DNA strands e. The four nucleobases are present in equal quanitites in a piece of DNA
b. They are perpendicular to the helical axis.
Which of the following statements concerning tRNAs is false? a. They have distinctive cloverleaf tertiary structures b. They are unique in that they are transcribed by DNA polymerases c. They contain many modified nucleobases d. They contain the anticodon sequence
b. They are unique in that they are transcribed by DNA polymerases
Which of the following codons does not code for an amino acid? a. AUG b. UAA c. CAU d. GUU e. All of these code for an amino acid
b. UAA
The protein which marks proteins for degradation is called: a. Chaperonin b. Ubiquitin c. Proteasomin d. Apoptosin e. None of these names is correct.
b. Ubiquitin
Protein synthesis in prokaryotes always starts with a. a methionine residue b. a formylmethionine residue c. a cysteine residue d. no specific residue
b. a formylmethionine residue
The backbone of nucleic acids consists of a. a phosphodiester bond between the 2' and 5' hydroxyl groups of neighboring sugars b. a phosphodiester bond between the 3' and 5' hydroxyl groups of neighboring sugars c. a glycosidic bond between a pyrimidine and a sugar d. a glycosidic bond between a purine and a sugar
b. a phosphodiester bond between the 3' and 5' hydroxyl groups of neighboring sugars
The initial step in the formation of an aminoacyl-tRNA is a. esterification of the tRNA b. activation of the amino acid by reaction with ATP c. activation of the tRNA by reaction with ATP d. interaction of the mRNA with the tRNA
b. activation of the amino acid by reaction with ATP
An aminoacyl-adenylate contains a. an ester bond b. an acid anhydride bond c. an amide bond d. an ether bond
b. an acid anhydride bond
In the DNA in chromatin, substitution mutations: a. are at a maximum in the linker regions b. are at a maximum in the nucleosomes c. occur maximally in the same places as deletion mutations d. are rarely seen, but deletion mutations are common
b. are at a maximum in the nucleosomes
Response elements a. are similar to operons in that they are controlled by a single promoter b. are enhancers of transcription activated by metabolic factors c. are not affected by steroids d. are silencers of transcription triggered by the presence of metal ions
b. are enhancers of transcription activated by metabolic factors
Operons a. control the expression of constitutive genes. b. are subject to positive or to negative control. c. are not affected by mutations in the genes for repressors or inducers. d. occur in both prokaryotes and eukaryotes.
b. are subject to positive or to negative control.
Amino acids linked to the 2'-end of a tRNA a. are regular substrates for protein synthesis. b. are transferred to the 3' position prior to their use in protein synthesis. c. are prompted hydrolysed off as part of a proofreading mechanism. d. never occur
b. are transferred to the 3' position prior to their use in protein synthesis.
N-formyl methionine a. can be found attached to every protein in E. coli. b. can be found attached to some proteins in E. coli. c. is never found on proteins in E. coli.
b. can be found attached to some proteins in E. coli.
Which of the following best describes the order of events at the promoter? a. open complex → closed complex → transcription initiation b. closed complex → open complex → transcription initiation c. open complex → transcription initiation → closed complex d. transcription initiation → open complex → closed complex
b. closed complex → open complex → transcription initiation
Phosphorylation of the CTD of RNA polymerase II occurs during which phase of transcription? a. initial binding to the promoter b. conversion from the closed complex to the open complex c. termination of transcription d. None of these
b. conversion from the closed complex to the open complex
Initiation of RNA biosynthesis involves a. recognition of the promoter region by the α subunit of RNA polymerase b. conversion of the closed-promoter complex to the open-promoter complex c. binding of one of the α subunits of RNA polymerase to each strand of DNA d. incorporation of four pyrimidine nucleotides in succession
b. conversion of the closed-promoter complex to the open-promoter complex
In a melting profile for DNA, the absorbance at 260 nm increases as result of the disruption of the DNA structure. What is the fundamental physical basis for the absorbance increase? a. the effective concentration of DNA changes b. denatured DNA absorbs light more strongly than native DNA because the bases have become unstacked c. native DNA absorbs light more strongly than denatured DNA because the bases are stacked d. the absorbance of DNA is highly sensitive to temperature
b. denatured DNA absorbs light more strongly than native DNA because the bases have become unstacked
Which of the following is not required for the elongation phase of protein synthesis? a. GTP b. fmet-tRNAfmet c. peptidyl transferase d. mRNA
b. fmet-tRNAfmet
Degradation of proteins a. happens randomly b. frequently makes use of proteasomes c. always requires ubiquitinylation of proteins to be degraded d. tends to target proteins with basic amino acid residues at their N-terminal ends
b. frequently makes use of proteasomes
Base pairs with a propeller-twist a. are found only in Z-DNA b. have optimum base stacking c. bind water in the minor groove d. have stronger hydrogen bonds than base pairs without a propeller twist
b. have optimum base stacking
The strands in the double helix a. both run in the same 3' → 5' direction, i.e., they are parallel. b. have their 3' → 5' directions opposed, i.e., they are anti-parallel. c. can be either parallel or anti-parallel. d. are perpendicular to one another. e. None of these
b. have their 3' → 5' directions opposed, i.e., they are anti-parallel.
It was recently discovered that AUG is not always the start codon in which of the following systems? a. viruses b. mammalian immune system proteins c. mitochondria d. all of these
b. mammalian immune system proteins
Eukaryotic mRNA requires a. less processing after synthesis than prokaryotic mRNA. b. more processing after synthesis than prokaryotic mRNA. c. about the same amount of processing after synthesis as prokaryotic mRNA.
b. more processing after synthesis than prokaryotic mRNA.
Polyadenylation of eukaryotic mRNA a. occurs at the 5' end. b. occurs at the 3' end. c. occurs at both ends. d. doesn't occur at all.
b. occurs at the 3' end.
Supercoiling of DNA a. is not observed in prokaryotes b. requires the action of topoisomerase enzymes c. does not require ATP d. is not observed in eukaryotes
b. requires the action of topoisomerase enzymes
The double helix of DNA is which level of structure? a. primary b. secondary c. tertiary d. quaternary e. None of these
b. secondary
A Shine-Dalgarno Sequence is a a. sequence of nucleotides in the DNA that interacts with the σ-subunit of RNA polymerase to begin transcription. b. sequence of nucleotides in an mRNA that interacts with the small subunit of a ribosome to begin translation. c. sequence of nucleotides in the DNA that interacts with ρ-protein to terminate transcription. d. sequence of nucleotides in an mRNA that functions to terminate translation.
b. sequence of nucleotides in an mRNA that interacts with the small subunit of a ribosome to begin translation.
In the process of translation, before an amino acid can be incorporated into a growing protein chain, the activation process of the amino acid involves _____. a. mRNA b. tRNA c. snRNA d. scRNA
b. tRNA
The sequences in eukaryotic DNA known as introns are a. those included in the final sequence of messenger RNA b. the intervening sequences not expressed in the final sequence of messenger RNA c. the binding sites for DNA polymerase d. the binding sites for RNA polymerase
b. the intervening sequences not expressed in the final sequence of messenger RNA
Which amino acids have unique codons? a. met, gly b. trp, met c. tyr, met d. stop, his
b. trp, met
What happens when a stop codon is reached by a ribosome (in the A site)? a. A termination tRNAter binds to the codon and is used to release the growing peptide from the P site tRNA. The ribosome then dissociates. b. A termination tRNAter binds to the codon and the growing peptide is transferred to it. When the peptidyl-tRNAter reaches the P site, the ribosome is signaled to release the protein. The ribosome then dissociates. c. A termination protein binds to the codon and is used to release the growing peptide from the P site tRNA. The ribosome then is likely to dissociate. d. A termination protein binds to the codon and the ribosome dissociates. A separate peptidyl transferase then releases the protein from the last tRNA to which was attached.
c. A termination protein binds to the codon and is used to release the growing peptide from the P site tRNA. The ribosome then is likely to dissociate.
Which contains a phosphoanhydride bond? a. DNA b. RNA c. ATP d. AMP e. None of these
c. ATP
Which of the following is not a key step in the activation of mRNA synthesis in eukaryotes? a. Binding of TBP to the DNA. b. Binding of other transcription factors. c. Binding of RNA Pol I. d. Phosphorylation of the RNA Pol. e. All of these are necessary to initiate RNA synthesis in eukaryotes.
c. Binding of RNA Pol I.
Eukaryotic and prokaryotic ribosomes can be compared in all these ways, except: a. Both have large and small subunits. b. Eukaryotic ribosomes are larger. c. Both contain the same number of RNA molecules. d. Eukaryotic ribosomes contain more proteins. e. All of these statements are accurate comparisons.
c. Both contain the same number of RNA molecules.
Which ends of eukaryotic mRNA are protected from degradation? a. 5' end only b. 3' end only c. Both ends d. Neither end e. The RNA is circular and has no ends.
c. Both ends
The helix can be untwisted by the action of which type of topoisomerase? a. Type I only b. Type II only c. Both types I and II d. Topoisomerases cannot untwist the helix
c. Both types I and II
Which linkage best describes the covalent bond between an amino acid (AA) and its tRNA? a. Amino group of AA linked to 5' −OH of tRNA. b. Amino group of AA linked to 5' phosphate of tRNA. c. Carboxyl group of AA linked to 3' −OH of tRNA. d. Carboxyl group of AA linked to 3' phosphate of tRNA
c. Carboxyl group of AA linked to 3' −OH of tRNA.
Which of the following statements concerning the genetic code is false? a. It is based on triplets. b. It is non-overlapping. c. Commas are used. d. It is degenerate.
c. Commas are used.
Identify the part of the RNA polymerase that constitutes the operator and the promoter and modulates the production of proteins whose amino acid sequence is specified by the structural genes under their control. a. Transcription start site b. Termination site c. Control site d. Restriction site
c. Control site
RNA is hydrolyzed in basic solution, but DNA is not. This occurs because a. thymine is found in DNA, and uracil is not b. DNA is double stranded, and RNA is single stranded c. DNA contains 2'-deoxyribose, but RNA does not d. RNA has modified bases, but DNA does not
c. DNA contains 2'-deoxyribose, but RNA does not
How do eukaryotic and prokaryotic RNA polymerases compare? a. Since eukaryotic RNA polymerases are more complex, little homology has been found between the actual protein sequences in the catalytic subunits. b. Since eukaryotic transcription is less complex than in prokaryotes, monomeric RNA polymerases are used. c. Despite their added complexity, eukaryotic and prokaryotic RNA polymerases are generally homologous. d. Eukaryotic and prokaryotic RNA polymerases are virtually identical.
c. Despite their added complexity, eukaryotic and prokaryotic RNA polymerases are generally homologous.
Where can drugs or polypeptides bind to DNA? a. The minor groove only. b. The major groove only. c. Either the minor or major groove. d. Neither the minor or major groove.
c. Either the minor or major groove.
The study of DNA changes that are not reflected in the base sequence is called: a. Molecular biology b. Histology c. Epigenetics d. Physical genetics
c. Epigenetics
Which of the conditions would result in the least amount of transcription of the lac operon?
c. III (high glucose, low lactose)
Which of the following statements concerning transfer RNA is true? a. It has the highest molecular weight of the commonly occurring forms of RNA. b. It has no internal hydrogen bonding. c. It bonds to amino acids in the course of protein synthesis. d. It is the smallest of the RNA types e. All of these are true
c. It bonds to amino acids in the course of protein synthesis.
How does the enzyme ATP(CTP):tRNA nucleotidyletransferase aid in quality control of formation of tRNA? a. It puts a CCA on the 5' end b. It puts a CCA on the 3' end c. It puts a CCACCA on the 3' end of defective tRNA molecules or tRNA-like molelcules that are not true tRNA d. None of these
c. It puts a CCACCA on the 3' end of defective tRNA molecules or tRNA-like molelcules that are not true tRNA
Which of the following is not true? a. The mechanism of activation of eukaryotic genes involves addition and removal of phosphate residues from some of the transcription factors. b. In plants, there are 5 RNA polymerases. c. RNA Pol IV is the primary RNA synthesizer in plants d. Of the RNA Polymerases in eukaryotes, Pol II is the most extensively studied.
c. RNA Pol IV is the primary RNA synthesizer in plants
Which enzyme transcribes genes encoding tRNA in eukaryotes? a. RNA polymerase I b. RNA polymerase II c. RNA polymerase III d. Different tRNAs are transcribed by different RNA polymerases.
c. RNA polymerase III
Which of the following transcription factors is involved in the elongation phase of eukaryotic transcription? a. TFIIA b. TFIID c. TFIIF d. There are no transcription factors associated with elongation.
c. TFIIF
The combination of events revolving around chromatin remodeling that controls transcription is known as: a. The genetic code b. The second genetic code c. The histone code d. Histone deacetylase code e. None of these
c. The histone code
As in prokaryotes, the regulatory regions for eukaryotic genes: a. may be close to the genes they control b. may be upstream of the genes they control c. may be downstream of the genes they control d. All of these are true
d. All of these are true
All of the following apply to attenuation mechanisms, except: a. They are used most often for operons for amino acid synthesis. b. They involve the synthesis of proteins in the regulation of RNA synthesis. c. The rate of RNA synthesis is regulated by the conformation of the protein being synthesized. d. They require the presence of partially completed mRNA molecules. e. All of these apply to attenuation mechanisms
c. The rate of RNA synthesis is regulated by the conformation of the protein being synthesized.
Which conclusion can be drawn from the experimental observation that a single strand of DNA contains 2100 dA residues and 1800 dT residues? a. There must have been some loss of material in the extraction because the number of dA and dT residues must be the same. b. This is a palindromic sequence. c. There must be 2100 dT and 1800 dA residues on the complementary strand. d. This must be prokaryotic DNA e. None of these
c. There must be 2100 dT and 1800 dA residues on the complementary strand.
What provides the energy for the conversion from the open complex to chain elongation? a. ATP hydrolysis distinct from any incorporation into the chain. b. Nucleotide hydrolysis associated with incorporation into the chain. c. Torsional stress built into the separating DNA strands. d. Binding of rho (ρ) factor to the holoenzyme. e. None of these
c. Torsional stress built into the separating DNA strands.
Identify the component of the prokaryotic promoter that is 40 to 60 bases subsequent to the transcription start site and that enhances the binding of RNA polymerase. a. Core promoter b. −35 element c. UP element d. Pribnow box
c. UP element
General transcription activation in eukaryotes requires a. a specific enhancer common to all genes b. a specific silencer common to all genes c. a protein called Mediator d. a CREB binding protein e. none of these
c. a protein called Mediator
A transcription factor is a. a subunit of RNA polymerase II that does not have a prokaryotic analogue. b. the part of the promoter sequence closest to the start of transcription. c. a protein other than RNA polymerase that is involved in transcription. d. a sequence that determines whether an upstream element will be an enhancer or silencer.
c. a protein other than RNA polymerase that is involved in transcription.
Propeller twists occur in B-DNA so that a. Z-DNA can form b. base pairing distances are optimized c. base stacking can better occur d. none of these
c. base stacking can better occur
The majority of protein synthesis occurs in the a. nucleus b. mitochondrion c. cytoplasm d. nucleolus
c. cytoplasm
Micro RNA technology is used in the treatment of _____. a. osteoporosis b. migraine c. hepatitis C d. anaemia
c. hepatitis C
The process of amino acid activation a. involves the formation of a peptide bond between the amino acid and tRNA b. takes place by formation of a mixed anhydride of the amino acid and tRNA c. involves the formation of an ester bond between the amino acid and tRNA d. none of these
c. involves the formation of an ester bond between the amino acid and tRNA
Control of transcription in prokaryotes does not involve a. enhancers. b. silencers. c. leucine zipper proteins. d. alternative σ factors.
c. leucine zipper proteins.
Histones contain large amounts of which of the following amino acids? a. histidine b. glutamic acid c. lysine d. leucine e. tryptophan
c. lysine
The genetic code is said to be degenerate. This means that a. each codon codes for more than one amino acid. b. each anticodon can interact with many different triplet sequences in the mRNA, which may differ in any or all of the three nucleotides. c. many of the amino acids are coded for by different codons. d. the code is universally used by virtually all species.
c. many of the amino acids are coded for by different codons.
A mutation in the lac A gene would result in a. continuous production of the proteins encoded by the three structural genes b. continuous production of the lac repressor c. normal operation of the lac operon, but with an alteration in the proteins encoded by the lac A gene d. no transcription from the lac operon
c. normal operation of the lac operon, but with an alteration in the proteins encoded by the lac A gene
Deoxythymidylate (dT) is a: a. purine base b. pyrimidine base c. pyrimidine based nucleotide d. purine based nucleotide e. nucleoside
c. pyrimidine based nucleotide
Consensus sequences are a. sequences that are invariant throughout the DNA. b. sequences required for transcription to occur c. sequences that have many bases in common d. sequences that lie far upstream of the core promoter.
c. sequences that have many bases in common
The following types of RNA are common to all organisms, except: a. mRNA b. rRNA c. snRNA d. tRNA e. All types are found in all organisms
c. snRNA
Topoisomerases are associated with a. production of RNA from DNA. b. joining of nucleotide monomers to make polynucleotides. c. supercoiling of DNA. d. ribosomes. e. All of these
c. supercoiling of DNA.
Which of the following RNAs is noted for having a "cloverleaf" structure? a. mRNA b. rRNA c. tRNA d. All of these
c. tRNA
What is the mode of action of puromycin in the inhibition of protein synthesis? a. inhibition of peptidyl transferase b. inactivation of EF−G c. termination of the growing polypeptide chain d. dissociation of mRNA from the ribosome
c. termination of the growing polypeptide chain
The _____ structure in DNA refers to the supercoiling of the DNA molecule. a. primary b. secondary c. tertiary d. quaternary
c. tertiary
Which of the following characteristics is associated with the B form of DNA? a. the sugars are located in the interior of the double helix b. the distance between base pairs along the axis of the helix is 8 Å c. the major and minor grooves are readily apparent d. the planes of the bases make about a 20 degree angle with the helix axis
c. the major and minor grooves are readily apparent
Ribosomal frameshifting in Influenza Virus A is caused by the fact that a. the virus has a modified genetic code b. the virus attacks the mRNA c. the ribosome reaches a rare arginine codon and stalls out d. none of these
c. the ribosome reaches a rare arginine codon and stalls out
The standard free energy change for the following reaction is about zero. amino acid + ATP + tRNA → aminoacyl-tRNA + AMP + PPi The driving force for this reaction in the cell is a. the relatively low concentrations of the reactants b. the subsequent reaction of peptide bond formation, which is energetically favorable c. the subsequent hydrolysis of pyrophosphate, which releases energy d. the increased resonance stability of the acyl group on aminoacyl-tRNA
c. the subsequent hydrolysis of pyrophosphate, which releases energy
At which position on the mRNA is the wobble base of the triplet codon? a. first position (5' letter) b. second position c. third position (3' letter) d. the wobble base can be at any position
c. third position (3' letter)
Where is the TATA box located? a. At the transcription start site (+1). b. −10 region. c. −25 region. d. −40 region
c. −25 region.
How many codons are known for each amino acid? a. 1 only b. 2 only c. 2 to 4 depending on the nature of the amino acid d. 1 to 6 depending on the nature of the amino acid
d. 1 to 6 depending on the nature of the amino acid
Which is not associated with bacterial promoters? a. the transcription start site b. the Pribnow box c. the −35 element d. 3' antiterminator
d. 3' antiterminator
How many codons are possible in a system in which a sequence of three bases specifies a single amino acid? a. 20 b. 24 c. 27 d. 64
d. 64
Which of the following is the best description of an operon? a. An enhancer that positively regulates gene expression. b. An silencer that negatively regulates gene expression. c. A binding element for the sigma (σ) factor. d. A group of genes under the control of a common promoter.
d. A group of genes under the control of a common promoter.
Which of the following modifications is likely to happen to the mRNA in a eukaryotic cell? a. capping of the 5' end b. addition of a poly-A tail to the 3' end c. removal of intervening sequences (introns) d. All of the above occur in eukaryotic cells.
d. All of the above occur in eukaryotic cells.
Quaternary structure refers to the non-covalent interaction(s) between polymeric units, such as two or more monomer protein units that noncovalently interact. Which of the following scenarios for nucleic acids most closely resembles quaternary structure? a. self-assembly of subunits in the tobacco mosaic virus b. interaction of DNA with proteins c. RNA and protein association in ribosomes d. All of these e. None of these
d. All of these
The tRNAs may bind to the standard stop codons a. in cellular organelles which use a modified genetic code. b. to accommodate the tRNA for the unusual amino acid selenocysteine. c. when the anticodon in a tRNA mutates to a sequence which can bind. d. All of these
d. All of these
Which of the following can be an epigenetic change to chromatin? a. methylation b. acetylation c. phosphorylation d. All of these e. None of these
d. All of these
Which of the following statements concerning ribosomes is true? a. They consist of two RNA subunits, one of which is larger than the other. b. They contain both RNA and protein. c. They can be dissociated and reassembled by controlling the Mg2+ concentration of the medium. d. All of these are true
d. All of these are true
Chain termination occurs, in vivo, when: a. RNA Polymerase gets to the end of the DNA. b. The factor called rho (ρ) binds to the DNA. c. A hairpin loop forms in the template. d. Either a hairpin loop forms or rho (ρ) catches up with transcription stalled by a hairpin loop e. None of these
d. Either a hairpin loop forms or rho (ρ) catches up with transcription stalled by a hairpin loop
Which of the following statements about the various RNA Polymerases in eukaryotes is false? a. Permanent RNAs, such as tRNA and rRNA use different RNA Polymerases. b. The different RNA Polymerases share some subunits. c. The RNA Polymerase for mRNA is designated RNA Pol II. d. Eukaryotic RNA polymerases are generally monomeric.
d. Eukaryotic RNA polymerases are generally monomeric.
Which of the conditions would result in the greatest amount of transcription of the lac operon?
d. IV (low glucose, high lactose)
Which of the following is not a property of the sigma (σ) subunit? a. It tells the RNA Polymerase where to sit down. b. It helps point the RNA Polymerase in the proper direction. c. It causes the RNA Polymerase to bind tightly to the DNA. d. It stays with the RNA Polymerase throughout synthesis.
d. It stays with the RNA Polymerase throughout synthesis.
CREB contains the following structural motif: a. Helix-turn-helix b. β−barrel c. Zinc finger d. Leucine zipper
d. Leucine zipper
Which of the following is more often associated with transcription being switched off? a. Presence of histone remodeling complexes SWI/SNF b. Active Histone Acetyltransferase c. Unmethylated cytosines d. Methylated cytosines e. None of these
d. Methylated cytosines
The glyosidic linkage in a nucleoside forms from the C-1' carbon of the sugar to the _____. a. N-9 nitrogen of pyrimidines b. N-6 nitrogen of purines c. N-2 nitrogen of purines d. N-1 nitrogen of pyrimidines
d. N-1 nitrogen of pyrimidines
Which ends of prokaryotic mRNA are protected from degradation? a. 5' end only b. 3' end only c. Both ends d. Neither end e. The RNA is circular and has no ends.
d. Neither end
The final form of mRNA in eukaryotes has all these features, except: a. There will be a special nucleotide cap on the 5' end of the mRNA. b. There is usually a poly A tail on the 3' end of the mRNA. c. The mature, active mRNA contains introns. d. Only a single protein is made from any mature mRNA molecule. e. All of these are true.
d. Only a single protein is made from any mature mRNA molecule.
Which of the following bases is not found in RNA? a. A b. C c. G d. T e. All of these are found in RNA.
d. T
Which of following statements concerning RNA transcription is false? a. The release of pyrophosphate from a nucleoside triphosphate drives the reaction. b. RNA is synthesized from the 5' end to the 3' end. c. DNA to RNA base pairing includes A to U and G to C. d. Transcription requires the use of a primer. e. None of these
d. Transcription requires the use of a primer.
A tRNA was determined to have the following anticodon sequence: 3'−GAI−5' (I represents the base hypoxanthine) Which of the following codons can form base pairs with this anticodon? a. 5'−CUA−3' b. 5'−CUC−3' c. 5'−CUU−3' d. all of these
d. all of these
Non-coding RNAs are known to: a. bind to mRNA targeting them for destruction b. bind to mRNA preventing their translation c. promote RNA silencing d. all of these
d. all of these
Which of the following is necessary for chain termination in protein synthesis? a. termination codons of mRNA b. release factors c. GTP d. all of these e. none of these
d. all of these
TATA-binding protein (TBP) is normally required for transcription by a. Pol I. b. Pol II. c. Pol III. d. all of these polymerases. e. none of these polymerases
d. all of these polymerases.
Which of the following is not true? a. A single activating enzyme can interact with all the tRNAs for its corresponding amino acid b. The selectivity of the aminoacyl-tRNA synthetases for their tRNA molecules is often called the second genetic code c. There are two major classes of aminoacyl-tRNA synthetases d. aminoacyl-tRNA synthetases link amino acids to tRNA molecules without the need for an energy source
d. aminoacyl-tRNA synthetases link amino acids to tRNA molecules without the need for an energy source
The A and B forms of DNA a. both have 10 base pairs per turn of the helix b. both have 11 base pairs per turn of the helix c. are both left-handed helices d. are both right-handed helices
d. are both right-handed helices
The fundamental differences between RNA and DNA are a. the organic bases only b. bases, ribose units, and the phosphodiester linkage c. bases, ribose units, and the glycosidic bond type d. bases and the ribose units only
d. bases and the ribose units only
Transcription in eukaryotes differs from RNA synthesis in prokaryotes a. by requiring a primer. b. by simplifying the process with multifunctional enzymes. c. in using more complex σ factors. d. by having multiple RNA polymerases rather than one.
d. by having multiple RNA polymerases rather than one.
In the template DNA strand formed during transcription, the area from the end of the Upstream Promoter (UP) element to the transcription start site (TSS) is called the _____. a. proximal promoter b. core promoter c. distal promoter d. extended promoter
d. extended promoter
The melting profile for a DNA is found to differ in two different salt solutions. In 0.001 M NaCl, Tm = 55° C, and in 0.01 M NaCl, Tm = 65° C. The fundamental reason for this change is a. higher salt concentration increases the electrostatic repulsions between phosphates b. the base stacking is more effective in high salt c. hydrogen bonding between complementary bases in enhanced at high salt d. higher salt concentration decreases the electrostatic repulsions between phosphates
d. higher salt concentration decreases the electrostatic repulsions between phosphates
Activation of amino acids always takes place a. on the ribosomes b. on a ribosomal subunit c. on the rough endoplasmic reticulum d. in the cytoplasm
d. in the cytoplasm
Initiation of transcription in eukaryotes is primarily controlled a. by two transcription factors b. by keeping the TATA-binding protein physically separated from other transcription factors c. by the order of binding of TFIIA and TFIIB d. in the formation of the preinitiation complex
d. in the formation of the preinitiation complex
In prokaryotic RNA synthesis a. the rate of incorporation of nucleotides is constant throughout the elongation process b. the ρ (rho) protein is always required for termination c. a unique series of three bases leads to termination d. inverted-repeat sequences in the DNA being transcribed can lead to termination
d. inverted-repeat sequences in the DNA being transcribed can lead to termination
Exceptions to the universality of the genetic code have been observed in a. viruses b. prokaryotes c. eukaryotes d. mitochondria and 16 other organisms, including some algae and fungae
d. mitochondria and 16 other organisms, including some algae and fungae
In protein synthesis formation of new peptide bonds is catalyzed by a. elongation factor EF−Tu b. elongation factor EF−Ts c. elongation factor EF−G d. peptidyl transferase
d. peptidyl transferase
Using the genetic code, indicate which polypeptides would be synthesized if poly (UGG) were used as a synthetic mRNA? a. poly(gly) b. poly(trp) c. poly(trp-val-gly) d. poly(trp), poly(val), poly(gly)
d. poly(trp), poly(val), poly(gly)
Deoxyadenylate (dA) is a: a. purine base b. pyrimidine base c. purine based nucleoside d. purine based nucleotide e. pyrimidine based nucleotide
d. purine based nucleotide
The maximum number of possible triplets of the four bases occurring in RNA, which are used to encode 20 amino acids, is _____. a. forty-two b. twenty-four c. forty-six d. sixty-four
d. sixty-four
Which of the following best describes the assembly process to initiate translation in prokaryotes? a. small ribosome subunit associates with large subunit; mRNA associates next; IFs bring in first f-Met-tRNA; bound NTP hydrolyzed. b. IF binds f-Met-tRNA; small ribosome subunit associates next; mRNA associates next; then large subunit; bound NTP hydrolyzed. c. IF w/ bound NTP binds f-Met-tRNA; mRNA associates next; small subunit associates next; bound NTP hydrolyzed; large subunit associates. d. small subunit associates with mRNA; IF w/ bound NTP brings in first f-Met-tRNA; IF then hydrolyses bound NTP; large subunit associates
d. small subunit associates with mRNA; IF w/ bound NTP brings in first f-Met-tRNA; IF then hydrolyses bound NTP; large subunit associates
Which category of RNA carries amino acids for the process of translation? a. mRNA b. rRNA c. snRNA d. tRNA
d. tRNA
Which of the following is not part of the core promoter? a. the transcription start site b. the Pribnow box (−10 region) c. the −35 region d. the UP element
d. the UP element
Which of the following is not a characteristic of catabolite activator protein (CAP)? a. it is a positive regulator of the lac operon b. when the cell has sufficient glucose and lactose, CAP will not be bound to the CAP binding site c. CAP binding near the promoter site depends on CAP complexation with cAMP d. the binding of CAP to DNA requires ATP hydrolysis
d. the binding of CAP to DNA requires ATP hydrolysis
The promoter site is a. the start site for transcription in DNA b. the binding site for regulatory proteins that stimulate transcription c. the general region of DNA downstream from the start site d. the site on DNA at which RNA polymerase binds to initiate transcription e. None of these
d. the site on DNA at which RNA polymerase binds to initiate transcription
After peptide bond formation takes place, what step is necessary for continuation of protein synthesis? a. binding of uncharged tRNA to the ribosome b. binding of EF−Tu c. binding of EF−Ts d. translocation of the ribosome
d. translocation of the ribosome
Which of the following is not a structural motif encountered in DNA-binding proteins? a. helix-turn-helix b. leucine zipper c. zinc finger d. β−barrel
d. β−barrel
Which of the following is involved in regulation of eukaryotic transcription? a. Histone acetyltransferase b. Histone deacetylase c. Chromatin remodeling complexes d. Octamer sliding e. All of the choices
e. All of the choices
Which of the following is associated with post-translational processing of proteins? a. Folding into the 3-dimensional shape b. Breaking large proteins into several components with differing functions c. Forming disulfide bonds d. Modification of specific amino acids e. All of these
e. All of these
Which of the following is true about riboswitches: a. They have a molecule sensing domain called an aptamer b. There are known pathogens that use riboswitches as part of their mechanism c. They respond to specific molecules and control translation in a way that is often similar to transcription attenuation d. They contain a sensing domain and a decision making domain e. All of these
e. All of these
Which of the following is true? a. Mediator is a giant complex with a mass over 1 million Daltons b. Mediator contains many subunits called Med proteins c. Mediator bridges the RNA Polymerase at the promoter region with enhancers d. Mediator is the ultimate regulator of eukaryotic transcription e. All of these
e. All of these
As in RNA and DNA synthesis, the synthesis of proteins follows the following steps, except: a. Activation of monomers b. Initiation c. Elongation d. Termination e. All of these are involved in all polymer synthesis
e. All of these are involved in all polymer synthesis
Splicing reactions for exons involve the following mechanisms, except: a. Small nuclear RNAs b. Ribozymes c. Lariat mechanisms d. Participation of special G residues e. All of these are involved in splicing reactions
e. All of these are involved in splicing reactions
The three dimensional structure of nucleic acids can include all except: a. Supercoiling b. Base stacking c. Hairpin loops d. Circular molecules e. All of these can be included in the three dimensional structure
e. All of these can be included in the three dimensional structure
Which of the following statements concerning small nuclear RNA is true? a. This RNA is usually found in snurps. b. This RNA is involved in removing exons from the RNA. c. This RNA was the first RNA shown to have catalytic activity. d. This RNA is small in size. e. All of these describe small nuclear RNA.
e. All of these describe small nuclear RNA.
Alternative removal of exons from mRNA is important in which of the following? a. Troponins and other contractile proteins. b. Different types of collagen. c. The disease lupus. d. Alzheimer's disease. e. All of these.
e. All of these.
Which of the following influence the amount of expression of an operon? a. Availability of the specific sigma factor for that operon. b. How well the Pribnow box conforms to the consensus sequence. c. Attenuation mechanisms. d. Presence of 3' 5' cyclic AMP. e. All of these.
e. All of these.
nosine or hypoxanthine can wobble with all the following bases, except: a. A b. C c. T d. U e. Inosine can wobble with all of these bases.
e. Inosine can wobble with all of these bases.
Which of the following is not a function of termination factors in E. coli? a. Cause the ribosomal subunits to dissociate. b. Bind to the stop codons on the mRNA. c. Carry GTP to provide energy for certain steps in the termination process. d. Release the new peptide from the ribosome. e. The termination factors do all of these
e. The termination factors do all of these
Which of the following is the most distinguishing difference between a purine and a pyrymidine a. purines are found in DNA while pyrimidines are found in RNA b. purines have nitrogens in the rings while pyrimidines do not c. pyrimidines have nitrogens in the rings while purines do not d. purines are found in RNA while pyrimidines are found in DNA e. purines are double ring structures while pyrimidines have a single ring
e. purines are double ring structures while pyrimidines have a single ring
The Z-form of DNA a. does not exist in nature. b. is right-handed. c. tends to occur in purine-only sequences. d. tends to occur in pyrimidine-only sequences. e. tends to occur in alternating purine-pyrimidine sequences.
e. tends to occur in alternating purine-pyrimidine sequences.
In eukaryotes, which of the following types of RNA undergo some base modification after polymerization of the monomers? a. mRNA b. tRNA c. rRNA d. mRNA and tRNA e. mRNA and rRNA f. all of these
f. all of these
