Chapter 14
A stretch of bacterial DNA 600 nucleotides long can code at most for a polypeptide of how many amino acids? A: 200 B: 100 C: 1800 D: 300 E: 600
A: 200
A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. The corresponding codon for the mRNA transcribed is A: 3'-UCA-5'. B: 3'-ACU-5'. C: 3'-UGA-5'. D: 5'-TCA-3'.
A: 3'-UCA-5'.
What is the proper order of the following events in the expression of a eukaryotic gene?1. translation2. RNA processing3. transcription4. modification of protein A: 3, 2, 1, 4 B: 1, 2, 3, 4 C: 1, 2, 4, 3 D: 4, 2, 3, 1 E: 2, 3, 4, 1
A: 3, 2, 1, 4
Which of the following is transcribed and then translated to form a protein product? A: A gene for a transcription factor B: An intron C: A gene for rRNA D: 5′ and 3′ UTRs E: A gene for tRNA
A: A gene for a transcription factor
Which of the following processes only occurs in eukaryotic gene expression? A: A poly-A tail is added to the 3' end of an mRNA, and a cap is added to the 5' end. B: Transcription can begin as soon as translation has assembled the first few amino acids in the polypeptide. C: RNA polymerase binds to the promoter. D: mRNA, tRNA, and rRNA are transcribed.
A: A poly-A tail is added to the 3' end of an mRNA, and a cap is added to the 5' end.
Which of the following is true of transcription factors? A: All of the listed responses are correct. B: Transcription factors are produced in a cell as a result of both gene transcription and translation. C: Transcription factors are present in eukaryotic cell nuclei. D: Transcription factors are proteins. E: Transcription factors bind to promoters.
A: All of the listed responses are correct.
Generally speaking, how many genetic codes are there? A: 1 B: 3 C: 4 D: 20 E: one for each organism
A: 1
If the 5′ → 3′ nucleotide sequence on the nontemplate DNA strand is CAT, what is the corresponding codon on mRNA? A: CAU B: GTA C: C: GUA D: UAC E: CAT
A: CAU For each gene, only one of the two DNA strands of a double-stranded DNA molecule is transcribed. This strand is called the template strand because it provides the pattern, or template, for the sequence of nucleotides in an RNA transcript (including mRNA). For any given gene, the same strand is used as the template every time the gene is transcribed. An mRNA molecule is complementary rather than identical to its DNA template because RNA nucleotides are assembled on the template according to base pairing. The pairs are similar to those that form during DNA replication, except that U (the RNA substitute for T) pairs with A. If the nontemplate DNA strand is CAT, then the template DNA strand is GTA. The mRNA nucleotides complementary to the DNA template nucleotides, GTA, are CAU.
Which of the following is a function of a poly-A tail in mRNA? A: It helps protect the mRNA from degradation by hydrolytic enzymes. B: It adds the modified guanine to the 3' end of the mRNA. C: It indicates the site of translational termination. D: It is a sequence that codes for the binding of RNA polymerase to the DNA.
A: It helps protect the mRNA from degradation by hydrolytic enzymes.
How is the template strand for a particular gene determined? A: It is established by the presence of the promoter. B: It doesn't matter which strand is the template because they are complementary and will produce the same mRNA. C: It is signaled by a polyadenylation signal sequence. D: It is the DNA strand that runs from the 3′ → 5′ direction. E: It is the DNA strand that runs from the 5′ → 3′ direction.
A: It is established by the presence of the promoter.
Which of the following would not be found in a bacterial cell? A: Small RNAs in spliceosome B: RNA polymerase C: Simultaneous transcription and translation D: mRNA E: rRNA
A: Small RNAs in spliceosome
Which summary of protein synthesis is correct? A: The mRNA is made on a DNA template, and then amino-acid-bearing tRNA's bind to it through codon-anticodon pairing. B: The tRNA's line up on a ribosome, and amino acids bind to them with hydrogen bonds. C: DNA strands separate in the nucleus to form mRNA. mRNA leaves the nucleus and is transcribed into tRNA on ribosomes. D: DNA transposons leave the nucleus, are transported to a ribosome, and catalyze the polymerization of amino acids in a protein. E: DNA exchanges its thymine units with uracil (U) in polymerase. This activates polymerase, and it starts joining amino acids together.
A: The mRNA is made on a DNA template, and then amino-acid-bearing tRNA's bind to it through codon-anticodon pairing.
A eukaryotic mutation upstream of a particular gene has been identified that changes the sequence of the TATA box to GATA. How would you predict that this mutation would affect the transcription of this gene? A: Transcription factor binding would be reduced or eliminated, and transcription of the gene would decrease dramatically. B: Transcription factors would bind in the middle of the gene sequence and transcribe the gene from that point. C:: Transcription factors would bind to the start point in the promoter region. D: Transcription would proceed normally.
A: Transcription factor binding would be reduced or eliminated, and transcription of the gene would decrease dramatically.
A ribozyme is __________. A: an RNA molecule that functions as an enzyme B: an example of rearrangement of exons caused by alternative RNA splicing C: the location in a cell where ribosomal RNAs (rRNAs) are made D: an exception to the one gene-one enzyme hypothesis E: a cutting enzyme involved in DNA damage repair
A: an RNA molecule that functions as an enzyme
Transcription factors are found in __________. A: archaea and eukaryotes B: bacteria and eukaryotes C: eukaryotes D: archaea E: bacteria and archaea
A: archaea and eukaryotes
Polysomes may be defined as __________. A: groups of ribosomes B: groups of peroxisomes C: microfilaments and microtubules D: groups of lysosomes E: groups of chromosomes
A: groups of ribosomes
Examine the simple metabolic pathway above. If A, B, and C are all substances required for growth of the organism that carries out this pathway, a strain that is mutant for the gene encoding enzyme 1 would be able to grow on which of the following media? A: minimal medium supplemented with nutrient B only B: minimal medium supplemented with nutrient A only C: minimal medium D: minimal medium with no supplements
A: minimal medium supplemented with nutrient B only
During translation in a eukaryotic cell __________. A: polypeptides are synthesized at ribosomes, according to instructions carried by mRNA B: mRNA is synthesized by the bonding of free nucleotides to the bases on the template strand of DNA C: ribosomes move out of the nucleus D: ribosomes move into the nucleus E: tRNA carries amino acid molecules to the nucleus, where they are added to a growing polypeptide chain
A: polypeptides are synthesized at ribosomes, according to instructions carried by mRNA
The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. What peptide sequence would be encoded by the sequence 5'-CCCAAATTTGGG-3'? A: pro-lys-phe-gly B: gly-phe-lys-pro C: gly-phe-pro-lys D: phe-gly-pro-lys E: lys-pro-gly-phe
A: pro-lys-phe-gly
Which of the following events in translation is the first to occur in eukaryotes? A: the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA B: binding of the larger ribosomal subunit to smaller ribosomal subunits C: elongation of the polypeptide D: base pairing of activated methionine-tRNA to AUG of the messenger RNA
A: the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic? A: whether or not the cell is compartmentalized by internal membranes B: the presence or absence of ribosomes C: the presence or absence of a rigid cell wal D: lwhether the cell contains DNA or RNA
A: whether or not the cell is compartmentalized by internal membranes
What is the correct tRNA anti-codon for the mRNA codon 5'-GCA-3'? A: 3'-UGC-5' B: 5'-UGC-3' C: 5'-CGU-3' D: 3'-CGT-5' E: 5'-CGT-3'
B: 5'-UGC-3'
Using the table on the left, identify a 5′→3′5′→3′ sequence of nucleotides in the DNADNA template strand for an mRNAmRNA coding for the polypeptide sequence Cys-Gly-Leu. A: 5′−ACGCCTGAG−3′ B: 5′−GAGTCCGCA−3′ C: 5′−AUCAAGCGU−3′ D: 5′−UGCGGACUA−3′
B: 5′−GAGTCCGCA−3′
A nucleotide deletion early in the coding sequence of a gene would most likely result in __________. A: multiple missense mutations B: All of the listed choices are correct. C: a nonfunctional protein D: a frameshift mutation E: a nonsense mutation
B: All of the listed choices are correct.
Which statement regarding the structure and function of tRNA is false? A: Each type of tRNA molecule translates a particular mRNA codon into a particular amino acid. B: Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases. C: The nucleotide sequence at both the amino acid attachment and the anticodon ends of each tRNA is instrumental in specifying which amino acid is attached to the tRNA by aminoacyl-tRNA synthetase. D: Although there are 61 codons that code for amino acids, there are only 45 different tRNA molecules. E: The second and third choices are false.
B: Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases.
A part of the promoter, called the TATA box, is said to be highly conserved in many different organisms through evolution. Which of the following correctly describes why this is the case? A: The sequence evolves very rapidly. B: Any mutation in the sequence is selected against. C: The sequence does not mutate. D: The sequence is found in many but not all promoters.
B: Any mutation in the sequence is selected against.
A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) already in the ribosome. Where does tRNA #2 move to after this bonding of lysine to the polypeptide? A: exit tunnel B: E site C: P site D: A site
B: E site
What mRNA codon would be made from the DNA triplet CGT? A: UCG B: GCA C: ATU D: TCU E: CTA
B: GCA
The P site of a ribosome does what? A: It recognizes the promoter during transcription initiation. B: It holds the tRNA carrying the growing polypeptide chain. C: It holds the tRNA that is carrying the next amino acid to be added to the growing polypeptide chain. D: It catalyzes the addition of amino acids to the tRNAs. E: It helps "unzip" DNA during transcription.
B: It holds the tRNA carrying the growing polypeptide chain.
Which enzyme synthesizes tRNA? A: DNA polymerase B: RNA polymerase C: Aminoacyl-tRNA synthetase D: Reverse transcriptase E: Ribosomal RNA
B: RNA polymerase
Which of the following is not involved in the formation of a eukaryotic transcription initiation complex? A: RNA polymerase II B: Small RNA molecules C: Promoter D: TATA box E: Transcription factors
B: Small RNA molecules
Which describes the arrangement of genetic information in a DNA molecule? A: A gene is composed of overlapping, three-nucleotide words on a template strand of DNA. B: The three-nucleotide words of a gene are arranged in a non-overlapping series on the DNA template strand. C: By analyzing the linear order of amino acids in a polypeptide, the exact order of the three-nucleotide words of a gene arranged on the template strand of DNA can be determined. D: The three-nucleotide words of a gene are serially arranged on both strands of DNA at a specific locus. E: By overlapping the three-nucleotide words of a gene, the amount of information a DNA molecule can hold is maximized.
B: The three-nucleotide words of a gene are arranged in a non-overlapping series on the DNA template strand.
Examine the simple metabolic pathway above. A mutation results in a defective enzyme 1. Which of the following results would be a consequence of that mutation? A: an accumulation of B and C and no production of A B: an accumulation of A and no production of B and C C: an accumulation of A and B and no production of C D: an accumulation of B and no production of A and C
B: an accumulation of A and no production of B and C
Ultraviolet (UV) radiation is damaging to cells because it __________. A: blocks all translation B: causes mutations in the DNA C: pokes holes in the nuclear envelope D: shreds the cytoskeleton and leads to free radicals E: deactivates the enzymes needed for DNA replication
B: causes mutations in the DNA
Garrod hypothesized that inherited diseases such as alkaptonuria, the inability to metabolize the chemical alkapton, occur because A: Garrod hypothesized that inherited diseases such as alkaptonuria, the inability to metabolize the chemical alkapton, occur because many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA. B: genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes. C: certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors. D: metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.
B: genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.
In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is __________. A: vague B: redundant C: inaccurate D: not specific E: incomplete
B: redundant
In eukaryotic cells, transcription CANNOT begin until __________. A: the DNA introns are removed from the template B: several transcription factors have bound to the promoter C: the 5' caps are removed from the mRNA D: the two DNA strands have completely separated and exposed the promoter
B: several transcription factors have bound to the promoter
Bacteria can transcribe and translate human genes to produce functional human proteins because __________. A: eukaryotes do not really need a nucleus B: the genetic code is nearly universal C: bacterial and eukaryotic RNA polymerases are identical D: RNA has catalytic properties E: bacterial ribosomes and eukaryotic ribosomes are identical
B: the genetic code is nearly universal
Examine the simple metabolic pathway above. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? A: 0 B: 1 C: 2 D: 3
C: 2
Examine the table of codons in the figure above. A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be A: 3'-AAC-GAC-GUC-AUA-5'. B: 5'-AUG-CTG-CAG-TAT-3'. C: 3'-AAA-GAA-TAA-CAA-5'. D: 5'-TTG-CTA-CAG-TAG-3'.
C: 3'-AAA-GAA-TAA-CAA-5'.
The nitrogenous base adenine is found in all members of which of the following groups of molecules? A: proteins, triglycerides, and testosterone B: proteins, ATP, and DNA C: ATP, RNA, and DNA D: glucose, ATP, and DNA
C: ATP, RNA, and DNA
Who formulated the one gene-one enzyme hypothesis? A: Franklin B: Hershey and Chase C: Beadle and Tatum D: Watson and Crick E: None of the choices is correct.
C: Beadle and Tatum
Which of the following shows the flow of genetic information? A: RNA to DNA to protein B: DNA to RNA to ribosomes C: DNA to RNA to protein D: protein to RNA to DNA
C: DNA to RNA to protein
Which statement correctly describes mRNA processing? A: Exons are cut out of the primary transcript and transported to the endoplasmic reticulum. B: Introns are cut out of the primary transcript and transported to the ribosomes. C: Introns are cut out of the primary transcript, and the resulting exons are spliced together. D: Introns are cut out of the primary transcript and spliced together at the end of the transcript. E: Exons are cut out of the primary transcript, and the introns are spliced together.
C: Introns are cut out of the primary transcript, and the resulting exons are spliced together.
What is the function of the release factor in translation? A: It separates tRNA in the A site from the growing polypeptide. B: It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. C: It binds to the stop codon in the A site in place of a tRNA. D: It releases the ribosome from the ER to allow polypeptides into the cytosol.
C: It binds to the stop codon in the A site in place of a tRNA.
There are how many types of bacterial RNA polymerase? A: Three B: Hundreds C: One D: Five E: Zero
C: One . In contrast, eukaryotes have at least three types of RNA polymerase in their nuclei; the one used for pre-mRNA synthesis is called RNA polymerase II.
Which binding site on a ribosome holds a tRNA attached to a growing polypeptide chain? A: The P site, A site, and E sites all hold tRNA attached to polypeptides. B: E site C: P site D: A site E: None of the listed responses are correct.
C: P site
Which of the following is not transcribed from DNA? A: Introns B: Exons C: Promoter D: tRNA E: 3′ and 5′ UTRs
C: Promoter
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of __________. A: DNA B: carbohydrates C: RNA D: lipids E: proteins
C: RNA
Which of the following is not part of the translation initiation complex? A: Initiator tRNA B: Large ribosomal subunit C: TATA box D: mRNA E: Small ribosomal subunit
C: TATA box
What is the direct result of a mutagen? A: decreased enzyme activity throughout the cell B: problems with mitosis C: a change in the sequence of DNA D: decreased permeability of the nuclear envelope E: a reduction in the number of tRNA molecules available for protein synthesis Submit
C: a change in the sequence of DNA
Which of the following mutations would be MOST likely to have a harmful effect on an organism? A: a single nucleotide deletion in the middle of an intron B: a single nucleotide deletion near the end of the coding sequence C: a single nucleotide insertion downstream of, and close to, the start of the coding sequence D: a deletion of three nucleotides near the middle of a gene
C: a single nucleotide insertion downstream of, and close to, the start of the coding sequence
Which of the following descriptions of nucleotide triplets best represents a codon? A: a triplet that has no corresponding amino acid B: a triplet at the opposite end of tRNA from the attachment site of the amino acid C: a triplet in the same reading frame as an upstream AUG D: a triplet separated spatially from other triplets
C: a triplet in the same reading frame as an upstream AUG
The type of mutation responsible for sickle-cell anemia is __________. A: a silent mutation B: a nucleotide-pair insertion C: both a point mutation and a nucleotide-pair substitution D: a nucleotide-pair substitution E: a point mutation
C: both a point mutation and a nucleotide-pair substitution
Which is a post-translational modification of a polypeptide? A: removal of introns and splicing of exons B: formation of a polysome that allows simultaneous formation of many polypeptides from one mRNA transcript C: cleavage of a polypeptide into two or more chains D: complementary base pairing of mRNA and tRNA in the ribosome E: The growing polypeptide signals the ribosome to attach to the ER.
C: cleavage of a polypeptide into two or more chains
In a eukaryotic cell, transcription takes place __________. A: in the cytoplasm B: on free ribosomes C: in the nucleus D: on the cell membrane E: in the rough endoplasmic reticulum
C: in the nucleus
During the transcription of a given portion of a DNA molecule __________. A: half of the mRNA is synthesized on half of one chain; then the other half of the mRNA is made on the other half of the DNA B: mRNA is synthesized on both chains of the DNA molecule at once C: mRNA is synthesized on only one of the chains D: mRNA is synthesized on both chains of the DNA molecule, but first on one side and then the other E: All of the choices are correct.
C: mRNA is synthesized on only one of the chains
The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually __________. A: serine B: alanine C: methionine D: glycine E: adenosine monophosphate
C: methionine
RNA polymerase __________. A: is the enzyme that catalyzes the joining of each amino acid to the right tRNA B: is the molecule of which ribosomes are constructed C: moves along the template strand of DNA, elongating an RNA molecule in a 5′ → 3′ direction D: is a ribozyme E: is the enzyme that transcribes exons but does not transcribe introns
C: moves along the template strand of DNA, elongating an RNA molecule in a 5′ → 3′ direction
Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because __________. A: each compartment in the cell (the nucleus, lysosome, and so forth) has its own set of ribosomes that synthesize proteins unique to that compartment B: proteins destined for secretion or for a specific compartment are all synthesized in the nucleus, whereas cytoplasmic proteins are all synthesized in the cytoplasm C: some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER D: there are two types of ribosomes: one group that synthesizes cytoplasmic proteins only, and another type that synthesizes secreted or compartment-specific proteins only E: ribosomes contain two types of subunits
C: some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER
During translation, amino acid chain elongation occurs until __________. A: the polypeptide is long enough B: all tRNAs are empty C: the ribosome encounters a "stop" codon D: the ribosome runs off the end of the mRNA strand E: no further amino acids are needed by the cell
C: the ribosome encounters a "stop" codon
The genetic code is essentially the same for all organisms. Based on this information, one can logically assume which of the following statements to be correct? A: Gene expression differs considerably in different organisms. B: DNA was the first genetic material. C: The same codons in different organisms translate into the different amino acids. D: A gene from an organism can theoretically be expressed by any other organism.
D: A gene from an organism can theoretically be expressed by any other organism.
Given a DNA molecule with the sequence of bases 5'-ATTGCA-3', what would be the sequence of the complementary strand? (It will be helpful to draw the DNA molecule when answering the question.) A: 5'-TAACGT-3' B: 3'-UAACGU-5' C: 5'-UAACGU-3' D: 3'-TAACGT-5'
D: 3'-TAACGT-5'
In transcription, __________. A: the RNA nucleotides used are produced by the cell B: the promoter region acts as an initial binding site for RNA polymerase C: only one of the DNA strands is used as the template D: All of the choices above are correct. E: None of the choices above is correct.
D: All of the choices above are correct.
Which of the following is not a post-translational modification that might be required of a protein before it becomes functional in a cell? A: Binding of two or more polypeptide chains. B: Attachment of sugars to amino acids of the protein C: Removal of an amino acid D: All of the listed responses are post-translational modifications required of some proteins. E: Cleavage of a polypeptide chain
D: All of the listed responses are post-translational modifications required of some proteins.
A series of studies on mutants of Neurospora identified three classes of mutants that needed arginine added to minimal media in order to grow. The production of arginine includes the following steps: precursor → ornithine → citrulline → arginine. What nutrient(s) have to be supplied to the mutants that had a defective enzyme for the ornithine → citrulline step in order to grow? A: The precursor B: Ornithine C: Either ornithine or citrulline D: Citrulline E: The precursor, ornithine, and citrulline
D: Citrulline
Which component is NOT directly involved in translation? A: tRNA B: ribosomes C: GTP D: DNA
D: DNA
Which statement about gene expression is true? A: It takes three genes to code for one protein. B: Each triplet has many different meanings. C: Each gene codes for three proteins. D: Each amino acid in a protein is coded for by three DNA bases. E: Each DNA base codes for three amino acids.
D: Each amino acid in a protein is coded for by three DNA bases.
Which accurately describes the usual process of transcription for eukaryotic genes? A: Exons and introns are transcribed, and the RNA transcribed from them leaves the nucleus. B: Introns are not transcribed. C: Both introns and exons are transcribed, but the RNA transcribed from them does not leave the nucleus. D: Exons are transcribed, but the RNA transcribed from introns does not leave the nucleus. E: Exons are not transcribed.
D: Exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.
A cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same template within the cell nucleus. Which mechanism bcould best account for this? A: Different systems of DNA unpacking could result in two different mRNAs. B: Different transcription factors were involved in the transcription of the two mRNAs. C: The two proteins have different functions in the cell. D: Exons from the same gene could be spliced in different ways to make different mRNAs. E: A point mutation might have altered the gene.
D: Exons from the same gene could be spliced in different ways to make different mRNAs.
Which of the following statements correctly defines the process of gene expression? A: Gene expression is the process by which proteins direct the synthesis of DNA. B: Gene expression is the process by which proteins direct the synthesis of RNA. C: Gene expression is the process by which RNA direct the synthesis of DNA. D: Gene expression is the process by which DNA directs the synthesis of proteins.
D: Gene expression is the process by which DNA directs the synthesis of proteins.
Which statement about transcription is false? A: In bacteria, transcription of a gene is initiated when the RNA polymerase by itself recognizes and binds to the promoter of the gene. B: A relaxation of chromatin packing in eukaryotic cells can facilitate the binding of transcription factors to a promoter of a gene. C: The initiation of gene transcription in eukaryotes requires the binding of proteins called transcription factors to the TATA box in the promoter region of a gene. D: In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes. E: All of the choices are correct.
D: In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes.
Where does RNA polymerase begin transcribing a gene into mRNA? A: It starts at one end of the chromosome. B: The ribosome directs it to the correct portion of the DNA molecule. C: It looks for the AUG start codon. D: It starts after a certain nucleotide sequence called a promoter. E: Transfer RNA acts to translate the message to RNA polymerase.
D: It starts after a certain nucleotide sequence called a promoter.
Which catalyzes the linkage between ribonucleotides to form RNA during gene expression? A: reverse transcriptase B: a ribozyme C: RNA ligase D: RNA polymerase E: tRNA
D: RNA polymerase
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA? A: ligaseRNA B: polymerase III C: RNA polymerase I D: RNA polymerase II
D: RNA polymerase II
In eukaryotes, which mechanism of gene regulation operates after transcription, but before translation of mRNA into protein? A: DNA packaging into nucleosomes B: action of repressors and activators C: protein degradation D: RNA splicing E: All of the choices are correct.
D: RNA splicing
Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following characteristics? A: shape of the A and P sites of ribosomes B: attachment of amino acids to tRNAs C: binding of ribosomes to mRNA D: bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
D: bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
The function of tRNA during protein synthesis is to __________. A: attach mRNA to the small subunit of the ribosome B: guide ribosome subunits out of the nucleus through nuclear pores C: process mRNA D: deliver amino acids to their proper site E: transcribe mRNA
D: deliver amino acids to their proper site
At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred __________. A: when an mRNA codon paired with a tRNA anticodon B: during translation C: in a double-stranded DNA molecule D: during transcription E: It is impossible to say, given this information.
D: during transcription
A signal peptide __________. A: is a sign to bind the small ribosomal unit at the initiation codon B: is part of the UTR following the 5′ cap C: directs an mRNA molecule into the lumen of the ER D: is the first 20 or so amino acids of a protein destined for a membrane location or for secretion from the cell E: is most likely to be found on cytosolic proteins produced by bacterial cells
D: is the first 20 or so amino acids of a protein destined for a membrane location or for secretion from the cell
A virus infects a cell and randomly inserts many short segments of DNA containing a stop codon throughout an organism's chromosomes. This will probably cause __________. A: the DNA to break up into thousands of short segments B: incorrect pairing between mRNA codons and amino acids C: no bad effects, as long as the stop codons are not also inserted into tRNA D: manufactured proteins to be short and defective E: All of the choices are correct.
D: manufactured proteins to be short and defective
A base-pair substitution mutation in a germ cell line is likely to have NO effect on phenotype if the substitution __________. A: changes the structure of an enzyme B: forms a new stop codon C: changes a stop codon to a codon specifying an amino acid D: occurs in an intron E: prevents the initiation of transcription of the DNA sequence that codes for ATP synthase
D: occurs in an intron
One strand of a DNA molecule has the following sequence: 3'-AGTACAAACTATCCACCGTC-5'. In order for transcription to occur in that strand, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated. A: AUG codon B: centromere C: intron D: promoter E: exon
D: promoter
Which of these is currently considered the best definition of a gene? A: A gene codes for a particular ribozyme. B: A gene codes for a single polypeptide. C: A gene codes for a single protein. D: A gene codes for a single enzyme. E: A gene codes for either a polypeptide or an RNA molecule.
E: A gene codes for either a polypeptide or an RNA molecule.
Which of the following individuals was the first to suggest that genes dictate phenotypes through enzymes? A: Edward Tatum B: Marshall Nirenberg C: George Beadle D: Thomas Hunt Morgan E: Archibald Garrod
E: Archibald Garrod
Which of the following is true of RNA processing? A: Exons are excised before the mRNA is translated. B: Large quantities of tRNA are assembled into ribosomes. C: The RNA transcript that leaves the nucleus may be much longer than the original transcript. D: Signal peptides are added to the 5′ end of the transcript. E: Assemblies of protein and small RNAs, called spliceosomes, may catalyze splicing.
E: Assemblies of protein and small RNAs, called spliceosomes, may catalyze splicing. After a primary transcript is made of a gene, non-coding introns are removed by spliceosomes and the remaining exons are joined together into a shortened messenger RNA (mRNA). A modified guanine nucleotide is also added to the 5' end, and a string of adenine nucleotides, called a poly-A tail, is added to the 3' end before the mRNA leaves the nucleus. After this RNA processing, a large ribosomal RNA (rRNA) subunit and a small rRNA subunit attach to each other and the mRNA to initiate translation, the synthesis of a polypeptide using the information in the mRNA.
Transcription involves the transfer of information from __________. A: the nucleus to the cytoplasm B: RNA to DNA C: mRNA to an amino acid sequence D: DNA to an amino acid sequence E: DNA to RNA
E: DNA to RNA
The energy required for assembly of a polypeptide by a ribosome comes directly from __________. A: ribozymes B: aminoacyl-tRNA synthetase C:transcription units D: ATP E: GTP
E: GTP ATP is the molecule hydrolyzed to directly provide energy for most other cellular processes. Ribozymes are RNA molecules with catalytic activity. Like other enzymes they lower activation energy but do not provide it. Aminoacyl-tRNA synthetases are the enzymes that catalyze the joining of each amino acid to the right tRNA. A transcription unit is the stretch of DNA downstream from the promoter that is transcribed into an RNA molecule.
How is the template strand for a particular gene determined? A: It is the DNA strand that runs from the 3′ → 5′ direction. B: It doesn't matter which strand is the template because they are complementary and will produce the same mRNA. C: It is signaled by a polyadenylation signal sequence. D: It is the DNA strand that runs from the 5′ → 3′ direction. E: It is established by the presence of the promoter.
E: It is established by the presence of the promoter. The two strands of a double-stranded DNA molecule are complementary, not identical, and therefore will not code for the same mRNA. All transcription occurs so that the RNA transcript is elongated in the 5′ → 3′ direction. Neither strand of the double-stranded DNA molecule is read in transcription to produce an RNA transcript elongated in the 3′ → 5′ direction. In eukaryotes, RNA polymerase transcribes a sequence on the DNA called the polyadenylation signal sequence, which specifies a polyadenylation signal (AAUAAA) in the RNA transcript. This signal is involved in termination, not initiation, of transcription.
On the off chance that you might contract an archaeal infection, how might it be treated? A: t could be treated with antibiotics such as streptomycin that inactivate bacterial ribosomes because archaea and bacteria have similar ribosomes. B: It could be treated with antiviral medications because archaea are similar to viruses. C: It could be treated with a vaccine. D: It could be treated with drugs that disrupt gene splicing because archaea remove introns in the nucleus before sending mRNA to ribosomes. E: None of the choices is correct.
E: None of the choices is correct.
Which of the following is a stop codon? A: AUG B: CAU C: AAG D: CAC E: UGA
E: UGA Stop codon: UGA, UAA, and UAG Start signal: AUG
What is a ribozyme? A: a mutated ribosome B: a DNA sequence near the promoter that assists in the binding of RNA polymerase C: an enzyme that holds open the DNA double helix while RNA polymerase adds nucleotides D: a biological catalyst consisting of DNA E: a biological catalyst made of RNA
E: a biological catalyst made of RNA
A geneticist found that a particular mutation had no effect on the polypeptide encoded by the gene. This mutation probably involved __________. A: a nonsense mutation B: the insertion of one nucleotide C: a missense mutation D: the deletion of one nucleotide E: a silent or neutral mutation
E: a silent or neutral mutation
How many nucleotides are needed to code for a protein with 450 amino acids? A: at least 150 B: at least 300 C: at least 450 D: at least 900 E: at least 1,350
E: at least 1,350
Transfer RNA __________. A: is translated into protein B: is produced in the nucleolus C: tags a growing polypeptide for export to the endoplasmic reticulum D: has catalytic activity and is thus a ribozyme E: binds to its specific amino acid in the active site of an aminoacyl-tRNA synthetase
E: binds to its specific amino acid in the active site of an aminoacyl-tRNA synthetase
A point mutation in which a single base pair is inserted or deleted from DNA is called a(n) __________. A: missense mutation B: nonsense mutation C: translocation mutation D: inversion mutation E: frame-shift mutation
E: frame-shift mutation
The bonds that hold tRNA molecules in the correct three-dimensional shape are __________. A: ionic bonds B: covalent bonds C: peptide linkages D: hydrophobic interactions E: hydrogen bonds
E: hydrogen bonds
After an RNA molecule is transcribed from a eukaryotic gene, what is removed and what is spliced together to produce an mRNA molecule with a continuous coding sequence? A: silencers ... enhancers B: promoters ... operators C: operators ... promoters D: exons ... introns E: introns ... exons
E: introns ... exons
The mRNA codons 5'-CAA-3' or 5'-CAG-3' are translated as the amino acid glutamine by __________. A: the small and large ribosomal units B: by tRNA molecules that have been charged with glutamine by two different aminoacyl-tRNA synthetases C: separate tRNA molecules with anticodons 3'-GUU-5' and 3'-GUC-5', respectively D: the tRNA with an anticodon 5'-GUU-3' and glutamine at its other end E: the same tRNA with the anticodon 3'-GUU-5'
E: the same tRNA with the anticodon 3'-GUU-5'
The number of nucleotide bases "read" together on the mRNA to designate each amino acid is _____; this unit is called a(n) __________. A: two ... anticodon B: two ... dipeptide C: three ... triose D: one ... amino acid E: three ... codon
E: three ... codon
