Deck 14: Gene Expression: From Gene to Protein

Question 1

Which of the following statements correctly compares transcription in prokaryotes and eukaryotes?

A)Prokaryotes have at least three types of RNA polymerases,whereas eukaryotes only have one.
B)Bacteria have one type of RNA polymerase,whereas eukaryotes have at least three.
C)RNA polymerase in both prokaryotes and eukaryotes produce the same RNA molecules.
D)Both eukaryotes and prokaryotes recognize a polyadenylation signal in order to terminate transcription.

Answer 1

B

Question 2

In eukaryotes there are several different types of RNA polymerase.Which type is involved in transcription of mRNA known as pre-mRNA?

A)ligase
B)RNA polymerase I
C)RNA polymerase II
D)RNA polymerase III

Answer 2

C

Question 3

Which of the following descriptions of nucleotide triplets best represents a codon?

A)a triplet separated spatially from other triplets
B)a triplet that has no corresponding amino acid
C)a triplet at the opposite end of tRNA from the attachment site of the amino acid
D)a triplet in the same reading frame as an upstream AUG

Answer 3

D

Question 4

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 DNA directs the synthesis of proteins.
C)Gene expression is the process by which proteins direct the synthesis of RNA.
D)Gene expression is the process by which RNA direct the synthesis of DNA.

Question 5

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

A)the protein product of the promoter
B)start and stop codons
C)ribosomes and tRNA
D)several transcription factors

Question 6

The "universal" genetic code is now known to have exceptions.Evidence for this can be found if which of the following statements is true?

A)if UGA,usually a stop codon,is found to code for an amino acid such as tryptophan (usually coded for by UGG only)
B)if one stop codon,such as UGA,is found to have the same effect on translation as another stop codon,such as UAA
C)if prokaryotic organisms are able to translate a eukaryotic mRNA and produce the same polypeptide
D)if several codons are found to translate to the same amino acid,such as serine

Question 7

How do small RNAs in the spliceosome initiate the splicing of the pre-mRNA?

A)by base pairing to the exons on each side of the intron
B)by binding to the 3'end of the pre-mRNA and removing the poly-A tail
C)by base pairing to specific sites along the intron
D)by base pairing to sites on both the intron and nearby exons

Question 8

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)A gene from an organism can theoretically be expressed by any other organism.
B)Gene expression differs considerably in different organisms.
C)DNA was the first genetic material.
D)The same codons in different organisms translate into the different amino acids.

Question 9

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)The sequence does not mutate.
C)Any mutation in the sequence is selected against.
D)The sequence is found in many but not all promoters.

Question 10

In which direction does RNA polymerase move along the DNA?

A)5' to 3' along whichever strand it's on
B)3' to 5' along the template strand
C)5' to 3' along the template strand
D)5' to 3' along the double-stranded DNA

Question 11

Garrod hypothesized that inherited diseases such as alkaptonuria,the inability to metabolize the chemical alkapton,occur because

A)metabolic enzymes require vitamin cofactors,and affected individuals have significant nutritional deficiencies.
B)many metabolic enzymes use DNA as a cofactor,and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA.
C)certain metabolic reactions are carried out by ribozymes,and affected individuals lack key splicing factors.
D)genes dictate the production of specific enzymes,and affected individuals have genetic defects that cause them to lack certain enzymes.

Question 12

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 would proceed normally.
B)Transcription factors would bind to the start point in the promoter region.
C)Transcription factor binding would be reduced or eliminated,and transcription of the gene would decrease dramatically.
D)Transcription factors would bind in the middle of the gene sequence and transcribe the gene from that point.

Question 13

Which of the following is a function of a poly-A tail in mRNA?

A)It adds the modified guanine to the 3' end of the mRNA.
B)It indicates the site of translational termination.
C)It is a sequence that codes for the binding of RNA polymerase to the DNA.
D)It helps protect the mRNA from degradation by hydrolytic enzymes.

Question 14

What is a ribozyme?

A)an enzyme that uses RNA as a substrate
B)an RNA with enzymatic activity
C)an enzyme that catalyzes the association between the large and small ribosomal subunits
D)an enzyme that synthesizes RNA as part of the transcription process

Question 15

Which of the following processes only occurs in eukaryotic gene expression?

A)mRNA,tRNA,and rRNA are transcribed.
B)RNA polymerase binds to the promoter.
C)A poly-A tail is added to the 3' end of an mRNA,and a cap is added to the 5' end.
D)Transcription can begin as soon as translation has assembled the first few amino acids in the polypeptide.

Question 16

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

Question 17

Which of the following statements best describes the function of the TATA box in eukaryotic promoters?

A)It is the recognition site for a specific transcription factor.
B)It sets the reading frame of the mRNA.
C)It is the recognition site for ribosomal binding.
D)It signals the end of the nucleotide sequence of the gene.

Question 18

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'-UGA-5'.
C)5'-TCA-3'.
D)3'-ACU-5'.

Question 19

Which of the following statements best describes the termination of transcription in bacteria?

A)RNA polymerase transcribes through the polyadenylation signal,causing proteins to associate with the transcript and cut it free from the polymerase.
B)RNA polymerase transcribes through the terminator sequence,causing the polymerase to separate from the DNA and release the transcript.
C)RNA polymerase transcribes through an intron,which causes the polymerase to let go of the transcript.
D)Once transcription has initiated,RNA polymerase transcribes until it reaches the end of the chromosome.

Question 20

A eukaryotic transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids.Which of the following statements best explains this fact?

A)Many noncoding stretches of nucleotides are present in eukaryotic DNA.
B)There is redundancy in the genetic code.
C)Many nucleotides are needed to code for each amino acid.
D)There are termination exons near the beginning of the mRNA.

Question 21

Which of the following statements correctly describes alternative RNA splicing?

A)It is a mechanism that can increase the rate of transcription.
B)It can allow the production of different protein products from a single mRNA.
C)It allows the production of similar proteins from different RNAs.
D)It increases the rate of transcription.

Question 22

An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC.Which of the following statements correctly describes the most likely result of this change?

A)tRNA will not form a cloverleaf.
B)The nearby stem end will pair improperly.
C)The amino acid methionine will not be covalently bound to the altered tRNA.
D)The anticodon will not bind with the mRNA codon.

Question 23

In an experimental situation,a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail.Which of the following would you expect her to find?

A)The mRNA would not be transported out of the nucleus.
B)The cell recognizes the absence of the tail and adds a new poly-A tail to the mRNA.
C)The molecule is digested by restriction enzymes in the nucleus.
D)The molecule is degraded by hydrolytic enzymes because it is no longer protected at the 5' end and the 3' end.

Question 24

Use the following model of a eukaryotic transcript to answer the question.E_1-4 refer to the exons,and I_1-3 refer to the introns in the pre-mRNA transcript.
5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3'
Suppose that an induced mutation removes most of the 5' end of the 5' UTR.What might be the result of this removal?

A)Removal of the 5' UTR has no effect because the exons remain intact.
B)Removal of the 5' UTR also removes the 5' cap,so the mRNA may be quickly degraded by hydrolytic enzymes.
C)The 3' UTR will duplicate,and one copy will replace the 5' end.
D)The first exon will not be read because I₁ will now serve as the UTR.

Question 25

What is the function of the release factor in translation?

A)It separates tRNA in the A site from the growing polypeptide.
B)It binds to the stop codon in the A site in place of a tRNA.
C)It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond.
D)It releases the ribosome from the ER to allow polypeptides into the cytosol.

Question 26

There are 61 mRNA codons that specify an amino acid,but only 45 tRNAs.This is best explained by the fact that

A)some tRNAs have anticodons that recognize four or more different codons.
B)the rules for base pairing between the third base of a codon and tRNA are flexible.
C)many codons are never used,so the tRNAs that recognize them are dispensable.
D)the DNA codes for all 61 tRNAs,but some are then destroyed.

Question 27

Which of the following statements describes one of the functions of GTP in translation?

A)GTP provides the energy for the formation of the initiation complex,using initiation factors.
B)GTP is hydrolyzed to provide phosphate groups for tRNA binding.
C)GTP is hydrolyzed to provide energy for breaking peptide bonds.
D)GTP supplies phosphates and energy to make ATP from ADP.

Question 28

Which of the following events in translation is the first to occur in eukaryotes?

A)elongation of the polypeptide
B)base pairing of activated methionine-tRNA to AUG of the messenger RNA
C)binding of the larger ribosomal subunit to smaller ribosomal subunits
D)the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

Question 29

What happens to the cut-out intron after alternative RNA splicing?

A)It is added back to the mRNA.
B)It is kept in the nucleus for insertion back into the genomic DNA.
C)It is transported out of the nucleus for translation in they cytosol.
D)It is rapidly degraded.

Question 30

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)binding of ribosomes to mRNA
B)shape of the A and P sites of ribosomes
C)attachment of amino acids to tRNAs
D)bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

Question 31

During the process of alternative RNA splicing,where on a pre-mRNA transcript does a spliceosome bind?

A)to the exons
B)to the 5' untranslated region
C)to the 3' untranslated region
D)on certain sequences of an intron

Question 32

Which of the following statements correctly describes the function of a signal peptide?

A)It directs an mRNA molecule into the Golgi apparatus.
B)It causes RNA polymerase to bind DNA and initiate transcription.
C)It terminates translation of the messenger RNA.
D)It assists in the translocation of polypeptides across the ER membrane.

Question 33

When the ribosome reaches a stop codon on the mRNA,no corresponding tRNA enters the A site.If the translation reaction were to be experimentally stopped at this point,which of the following sets of structures would you be able to isolate from the cell?

A)an assembled ribosome with a polypeptide attached to the tRNA in the P site
B)separated ribosomal subunits,a polypeptide,and free tRNA
C)an assembled ribosome with a separated polypeptide
D)separated ribosomal subunits with a polypeptide attached to the tRNA

Question 34

Use the following model of a eukaryotic transcript to answer the question.E_1-4 refer to the exons,and I_1-3 refer to the introns in the pre-mRNA transcript.
5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3'
Which components of the previous molecule will also be found in mRNA in the cytosol?

A)5' UTR I₁ I₂ I₃ UTR 3'
B)5' E₁ E₂ E₃ E₄ 3'
C)5' UTR E₁ E₂ E₃ E₄ UTR 3'
D)5' I₁ I₂ I₃ 3'

Question 35

The process of translation in both prokaryotes and eukaryotes requires tRNAs,amino acids,and ribosomal subunits.Which of the following components must also be present for translation to proceed?

A)protein factors and ATP
B)protein factors and GTP
C)polymerases and GTP
D)signal peptides plus release factor

Question 36

Which of the following experimental procedures is most likely to speed up mRNA degradation in a eukaryotic cell?

A)lengthening of the poly-A tail
B)removal of the 5' cap
C)removal of C nucleotides
D)removal of one or more exons

Question 37

A mutation in a cell results in a structural change in the signal-recognition particle (SRP)so that it does not bind to the translocation complex in the ER correctly.Which of the following processes will occur because of this mutation?

A)The large and small subunits of the ribosome will not bind to each other during translation.
B)Proteins produced during translation that are destined for the ER will not be translocated into the ER.
C)Proteins produced during translation that are destined for the ER will be translocated into the ER.
D)The initiation of translation will not occur normally.

Question 38

A particular triplet of bases in the coding sequence of DNA is AAA.The anticodon on the tRNA that binds the mRNA codon is

A)TTT.
B)UUA.
C)UUU.
D)AAA.

Question 39

Use the following model of a eukaryotic transcript to answer the question.E_1-4 refer to the exons,and I_1-3 refer to the introns in the pre-mRNA transcript.
5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3'
Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I₁).Which of the following results might occur?

A)loss of the gene product
B)loss of E₁
C)premature transcriptional termination
D)inclusion of I₁ in the mRNA

Question 40

A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine.What would be a potential consequence for a cell in which this happens? Remember that phenylalanine may be encoded by multiple codons.

A)None of the proteins in the cell will contain phenylalanine.
B)Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
C)The cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.
D)The ribosome will skip a codon every time a UUU is encountered.

Question 41

Which of the following statements correctly defines the most current and complete description of a gene?

A)a unit of heredity that causes formation of a phenotypic characteristic
B)a DNA subunit that codes for a single complete protein
C)a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
D)a DNA-RNA sequence combination that results in an enzymatic product

Question 42

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon.What is the most likely result of this mutation in the protein product?

A)a base-pair substitution
B)a nucleotide mismatch
C)a frameshift mutation
D)a polypeptide missing an amino acid

Question 43

Which of the following types of mutations could result in a frameshift mutation?

A)a base insertion only
B)a base deletion only
C)a base substitution only
D)either an insertion or a deletion of a base

Question 44

Which small-scale mutation would be most likely to have the least negative effect on the function of a protein?

A)a base substitution
B)a base deletion near the start of a gene
C)a base deletion near the end of the coding sequence,but not in the terminator codon
D)deletion of three bases near the start of the coding sequence,but not in the initiator codon

Question 45

Which of the following DNA mutations is likely to have the most negative effect on the protein it specifies?

A)a base-pair deletion
B)a codon substitution
C)a substitution in the last base of a codon
D)a codon deletion

Question 46

Examine the simple metabolic pathway in the figure above.According to Beadle and Tatum's hypothesis,how many genes are necessary for this pathway?

A)0
B)1
C)2
D)3

Question 47

Which of the following statements is correct regarding protein synthesis in prokaryotes and eukaryotes?

A)Transcription and translation can occur at the same time in both organisms.
B)Translation can begin while transcription is still in progress in prokaryotes,but not in eukaryotes.
C)The RNA produced during transcription is then modified in both types of organisms.
D)In prokaryotes,transcription produces a protein,but in eukaryotes,it produces RNA.

Question 48

Which of the following types of mutation,resulting in an error in the mRNA just after the 5ʹ AUG start codon,is likely to have the most serious effect on the polypeptide product?

A)a deletion of a codon
B)a deletion of two nucleotides
C)a substitution of the third nucleotide in an ACC codon
D)a substitution of the first nucleotide of a GGG codon

Question 49

What is the effect of a nucleotide-pair substitution that results in a nonsense mutation in a gene?

A)It changes an amino acid in the encoded protein.
B)It has no effect on the amino acid sequence of the encoded protein.
C)It introduces a premature stop codon into the mRNA.
D)It alters the reading frame of the mRNA.

Question 50

In comparing DNA replication with RNA transcription in the same cell,which of the following is true only of replication?

A)It uses RNA polymerase.
B)It makes a new molecule from its 5' end to its 3' end.
C)The process is extremely fast once it is initiated.
D)The entire template molecule is represented in the product.

Question 51

Examine the simple metabolic pathway in the figure 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 A and no production of B and C
B)an accumulation of A and B and no production of C
C)an accumulation of B and no production of A and C
D)an accumulation of B and C and no production of A

Question 52

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)5'-TTG-CTA-CAG-TAG-3'.
B)3'-AAC-GAC-GUC-AUA-5'.
C)5'-AUG-CTG-CAG-TAT-3'.
D)3'-AAA-GAA-TAA-CAA-5'.

Question 53

Suppose that an error in transcription alters the formation of a single tRNA molecule in a cell.The altered tRNA still attaches to the same amino acid (Phe),but its anticodon loop has the sequence AAU,which binds to the mRNA codon UUA (usually specifying the amino acid leucine,Leu).What will be the effect on the translation of polypeptides in this cell?

A)The altered tRNA will cause this mRNA to make only nonfunctioning product.
B)The tRNA-Leu will not be able to enter the ribosome to bind to the UUA codon.
C)One altered tRNA molecule will have little effect because it will compete with many "normal" ones.
D)The altered tRNA will result in an amino acid variant in all copies of the protein.

Question 54

In the 1920s,Hermann Muller discovered that X-rays caused genetic changes in the fruit fly Drosophila.In a related series of experiments in the 1940s,other scientists discovered that other types of chemicals have a similar effect.A new chemical food additive is developed by a cereal manufacturer.Why is it necessary to test for its ability to cause mutation?

A)We worry that it might cause mutation in cereal grain plants.
B)We want to make sure that it does not emit radiation.
C)We want to be sure that it increases the rate of mutation sufficiently.
D)We want to prevent any chance that it might cause mutations.

Question 55

Examine the table of codons in the figure above.What amino acid sequence will be produced based on the following mRNA codon sequence?
5'-AUG-UCU-UCG-UUA-UCC-UUG-3'

A)met-arg-glu-arg-glu-arg
B)met-glu-arg-arg-glu-leu
C)met-ser-leu-ser-leu-ser
D)met-ser-ser-leu-ser-leu

Question 56

When the genome of a particular species is said to include 20,000 protein-coding regions,what does this imply?

A)There are 20,000 genes.
B)Each gene codes for one protein.
C)There are also additional genes for RNAs other than mRNA.
D)The species is highly evolved.

Question 57

What must happen to a newly made polypeptide before it can be secreted from a cell?

A)It must be translated by a ribosome that remains free of attachment to the ER.
B)Its signal sequence must target it to the ER,after which it goes to the Golgi.
C)Its signal sequence must be cleaved off before the polypeptide can enter the ER.
D)Its signal sequence must target it to the plasma membrane,where it causes exocytosis.

Question 58

Examine the simple metabolic pathway in the figure 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
B)minimal medium supplemented with nutrient A only
C)minimal medium supplemented with nutrient B only
D)minimal medium with no supplements

Question 59

Which of the following mutations is most likely to cause a phenotypic change?

A)a duplication of all or most introns
B)a nucleotide substitution in an exon coding for a transmembrane protein
C)a single nucleotide deletion in an exon coding for an active site of a protein
D)a frameshift mutation one codon away from the 3' end of the nontemplate strand

Question 60

In what way could a point mutation in DNA make a difference in the function of a protein?

A)It might result in a chromosomal translocation.
B)It might exchange one stop codon for another stop codon.
C)It might exchange one serine codon for a different serine codon.
D)It might substitute a different amino acid in the protein,which could change its function.

Question 61

Which component is not directly involved in translation?

A)GTP
B)DNA
C)tRNA
D)ribosomes

Question 62

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5'-CCG-ACG-3' (mRNA).The charged transfer RNA molecules shown in the figure below (with their anticodons shown in the 3' to 5' direction)are available.Two of them can correctly match the mRNA so that a dipeptide can form. The anticodon loop of the first tRNA that will complement this mRNA is

A)3'-GGC-5'.
B)5'-GGC-3'.
C)5'-ACG-3'.
D)5'-UGC-3'.

Question 63

Given the locally unwound double strand of DNA in the figure above,in which direction and on what strand does the RNA polymerase move during transcription?

A)3' → 5' along the template strand
B)5' → 3' along the template strand
C)3' → 5' along the complementary strand
D)5' → 3' along the complementary strand

Question 64

Which of the following is not true of a codon?

A)It may code for the same amino acid as another codon.
B)It never codes for more than one amino acid.
C)It extends from one end of a tRNA molecule.
D)It is the basic unit of the genetic code.

Question 65

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5'-CCG-ACG-3' (mRNA).The charged transfer RNA molecules shown in the figure below (with their anticodons shown in the 3' to 5' direction)are available.Two of them can correctly match the mRNA so that a dipeptide can form. The dipeptide that will form will be

A)cysteine-alanine.
B)proline-threonine.
C)glycine-cysteine.
D)alanine-alanine.

Question 66

The figure above represents a tRNA molecule that recognizes and binds a particular amino acid (in this instance,phenylalanine).Which codon on the mRNA strand codes for this amino acid?

A)UGG
B)GUG
C)GUA
D)UUC

Question 67

The tRNA shown in the figure above has its 3' end projecting beyond its 5' end.Which of the following will occur at this 3' end?

A)The codon and anticodon will complement each other.
B)The amino acid will bind covalently.
C)The small and large subunits of the ribosome will attach to it.
D)The 5' cap of the mRNA will become covalently bound.

Question 68

Using the figure below,identify a 5' → 3' sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys. Figure 14.6

A)5′-UUUCCCAAA-3′
B)5′-GAACCCCTT-3′
C)5′-CTTCGGGAA-3′
D)5′-AAACCCUUU-3′

Question 69

Which of the following mutations would be most likely to have a harmful effect on an organism?

A)a deletion of three nucleotides near the middle of a gene
B)a single nucleotide deletion in the middle of an intron
C)a single nucleotide deletion near the end of the coding sequence
D)a single nucleotide insertion downstream of,and close to,the start of the coding sequence

Question 70

Examine the table of codons in the figure above.A peptide has the sequence NH₂-phe-pro-lys-gly-phe-pro-COOH.Which of the following sequences in the coding strand of the DNA could code for this peptide?

A)3'-UUU-CCC-AAA-GGG-UUU-CCC
B)3'-AUG-AAA-GGG-TTT-CCC-AAA-GGG
C)5'-TTT-CCC-AAA-GGG-TTT-CCC
D)5'-GGG-AAA-TTT-AAA-CCC-ACT-GGG

Question 71

In eukaryotic cells,transcription cannot begin until

A)the two DNA strands have completely separated and exposed the promoter.
B)several transcription factors have bound to the promoter.
C)the 5' caps are removed from the mRNA.
D)the DNA introns are removed from the template.

Question 72

During transcription of the DNA in the figure above,where would the promoter be located?

A)at the 3' end of the newly made RNA
B)to the right of the template strand
C)to the left of the template strand
D)to the right of the coding strand

Question 73

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.Which component of the complex described enters the exit tunnel through the large subunit of the ribosome?

A)tRNA with attached lysine (#1)
B)tRNA with polypeptide (#2)
C)tRNA that no longer has attached amino acid
D)newly formed polypeptide

Question 74

The anticodon of a particular tRNA molecule is

A)complementary to the corresponding mRNA codon.
B)complementary to the corresponding triplet in rRNA.
C)the part of tRNA that bonds to a specific amino acid.
D)catalytic,making the tRNA a ribozyme.

Question 75

Which of the following is not true of RNA processing?

A)Exons are cut out before mRNA leaves the nucleus.
B)Nucleotides may be added at both ends of the RNA.
C)Ribozymes may function in RNA splicing.
D)RNA splicing can be catalyzed by spliceosomes.

Question 76

What type of bonding is responsible for maintaining the shape of the tRNA molecule in the figure above?

A)covalent bonding between sulfur atoms
B)ionic bonding between phosphates
C)hydrogen bonding between base pairs
D)van der Waals interactions between hydrogen atoms

Question 77

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)A site
B)P site
C)E site
D)exit tunnel