Chapter 17 Reading Quiz
Last Modified: 2016-03-08
Which of the following statements about transcription is correct?
During elongation, the RNA strand is extended in the 5' to 3' direction.
How is a mutation in a bacterial cell that deletes three base pairs 10 base pairs upstream from the +1 site likely to affect transcription and why?
Initiation will be inhibited because sigma cannot bind to the promoter.
Why are ribonucleoside triphosphates the monomers required for RNA synthesis rather than ribonucleoside monophosphates?
Ribonucleoside triphosphates have high potential energy, making the polymerization reaction exergonic.
During transcription, in which direction is (1) RNA synthesized and in which direction is (2) the DNA template "read"?
A promoter is ______.
a sequence in DNA that brings RNA polymerase near the site for transcription
(a) Add another OH to the sugar.
(b) Remove a CH3 group from the base.
(b) only one strand is being used as template.
(c) the product contains U.
What is the process called that converts the genetic information stored in DNA to an RNA copy?
DNA does not store the information to synthesize which of the following?
Transcription begins at a promoter. What is a promoter?
A site in DNA that recruits the RNA Polymerase
Which of the following statements best describes the promoter of a protein-coding gene?
The promoter is a nontranscribed region of a gene.
What determines which base is to be added to an RNA strand during transcription?
Base pairing between the DNA template strand and the RNA nucleotides
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?
What happens to RNA polymerase II after it has completed transcription of a gene?
It is free to bind to another promoter and begin transcription.
In the diagram below, the gray unit represents _____.
RNA polymerase; RNA polymerase untwists a portion of the DNA double helix.
In the diagram below, the green unit represents _____.
In the diagram below, the two blue strands represent _____.
Which of these correctly illustrates the pairing of DNA and RNA nucleotides?
GTTACG ---> CAAUGC
The direction of synthesis of an RNA transcript is _____.
5' —> 3'
The micrograph in Figure 17.5a shows a DNA-mRNA hybrid. If the noncoding regions of the gene did not exist, what would the micrograph look like?
All of the loops would be missing.
The following eukaryotic structural gene contains two introns and three exons. The table below shows four possible mRNA products of this gene. Use the labels to explain what mutation(s) may have resulted in each mRNA. Drag the correct label to each location in the table. Labels may be used once, more than once, or not at all.
1) Mutations in splicing signal sequences in intron 2.
2) Mutation in the gene's promoter sequence.
3) Mutation in splicing signal sequences in both intron 1 and intron 2.
4) No mutation in any splicing signal sequences.
Suppose that a portion of double-stranded DNA in the middle of a large gene is being transcribed by an RNA polymerase. As the polymerase moves through the sequence of six bases shown in the diagram below, what is the corresponding sequence of bases in the RNA that is produced? Enter the sequence of bases as capital letters with no spaces and no punctuation. Begin with the first base added to the growing RNA strand, and end with the last base added.
During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'→5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand. For any given gene, what ultimately determines which DNA strand serves as the template strand?
the base sequence of the gene's promoter
After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
1) A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.
2) A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
3) Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.
5' caps and 3' poly(A) tails of eukaryotic mRNAs ______.
protect mRNA from degradation and enhance translation
Which statement is most accurate concerning the function(s) of the 5' cap and the 3' poly(A) tail of eukaryotic mRNAs?
Both structures are important for initiating translation and extending the lifespan of the mRNA.
During RNA processing a(n) _____ is added to the 5' end of the RNA.
modified guanine nucleotide
During RNA processing a(n) _____ is added to the 3' end of the RNA.
a long string of adenine nucleotides
Spliceosomes are composed of _____.
snRNPs and other proteins
The RNA segments joined to one another by spliceosomes are _____.
Translation occurs in the _____.
What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?
What name is given to the process in which pre-mRNA is edited into mRNA?
Polypeptides are assembled from _____.
RNA processing converts the RNA transcript into _____.
Which tRNA anticodon(s) could decode the mRNA codon CAG (recall that codons are always written in the 5'—>3' direction and anticodons are written in the 3'—>5' direction)?
GUU or GUC
The wobble hypothesis explains ______.
the ability of some tRNAs to read more than one codon
What is recognized by an aminoacyl tRNA synthetase?
one amino acid and the set of tRNAs that are coupled to that amino acid
How does the bacterial ribosome recognize where to start translation?
The small ribosomal subunit binds to a sequence in the mRNA just upstream of the start codon.
Answer the following questions about translation elongation in the wild-type and mutant strains. Drag the correct label to each target in the table. Labels may be used more than once.
1) yes; no
2) no; yes
3) yes; yes
4) yes; no
In eukaryotic cells, the processes of protein synthesis occur in different cellular locations. Drag the labels to the appropriate targets to identify where in the cell each process associated with protein synthesis takes place.
a) formation of ribosomal subunits
b) attachment of an amino acid to tRNA
c) translation of cytoplasmic proteins
d) transcriptions and RNA processing
e) translation of secreted proteins
RNA plays important roles in many cellular processes, particularly those associated with protein synthesis: transcription, RNA processing, and translation. Drag the labels to the appropriate bins to identify the step in protein synthesis where each type of RNA first plays a role. If an RNA does not play a role in protein synthesis, drag it to the “not used in protein synthesis” bin.
Transcription/RNA processing: pre-mRNA, mRNA, snRNA
Translation: rRNA, tRNA
Not used in protein synthesis: RNA primers
Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation...Based on this information, what is the minimum size of a codon for these hypothetical Martian life-forms?
Ribosomes provide the scaffolding on which tRNAs interact with mRNA during translation of an mRNA sequence to a chain of amino acids. A ribosome has three binding sites, each of which has a distinct function in the tRNA-mRNA interactions. Drag the appropriate tRNAs to the binding sites on the ribosome to show the configuration immediately before a new peptide bond forms. Note that one of the binding sites should be left empty.
Leave site E open.
In site P, the thing with A U A at the bottom goes there, and it's the one that has three things on top rather than the one circle.
In site A, the thing with U C C at the bottom goes there, and it has just a circle attached to the top.
The diagram below shows an mRNA molecule that encodes a protein with 202 amino acids. The start and stop codons are highlighted, and a portion of the nucleotide sequence in the early part of the molecule is shown in detail. At position 35, a single base-pair substitution in the DNA has changed what would have been a uracil (U) in the mRNA to an adenine (A). Based on the genetic code chart above, which of the following would be the result of this single base-pair substitution?
A nonsense mutation resulting in early termination of translation.
The DNA in a cell’s nucleus encodes proteins that are eventually targeted to every membrane and compartment in the cell, as well as proteins that are targeted for secretion from the cell...For each protein, identify its targeting pathway: the sequence of cellular locations in which the protein is found from when translation is complete until it reaches its final (functional) destination. (Note that if an organelle is listed in a pathway, the location implied is inside the organelle, not in the membrane that surrounds the organelle.)
PFK: Cytoplasm only
Insulin: ER --> Golgi --> Outside of cell
Sort each description by the type of RNA it describes. Drag each item to the appropriate bin.
tRNA: contains an anticodon; has amino acids covalently attached for production of protein
mRNA: contains exons; determines the amino acid sequence for a protein - I take it that's what this means
rRNA: is a component of ribosomes; is the most abundant form of RNA
Indicate at which step of the replication-transcription-translation process each type of RNA first plays a role. During which step of the replication-transcription-translation process does each type of RNA first play a role? Drag each item to the appropriate bin.
1) Replication: No RNA is involved
2) Transcription/RNA processing: mRNA
3) Translation: rRNA and tRNA
During the elongation phase of translation, individual tRNAs move through the three sites of the ribosome in the following sequence _____.
A --> P --> E
Where does translation take place?
Which nucleic acid is translated to make a protein?
Which of the following processes is an example of a post-translational modification?
Which of the following steps occurs last in the initiation phase of translation?
The large ribosomal subunit joins the complex.
At which site do new aminoacyl tRNAs enter the ribosome during elongation?
What is meant by translocation?
The ribosome slides one codon down the mRNA.
True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.
Complete the following vocabulary exercise related to the process of translation of mRNA to protein by the ribosome. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.
3) aminoacyl-tRNA synthetase.
Which of these is a tRNA?
What enzyme catalyzes the attachment of an amino acid to tRNA?
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.
What is the name of the process shown in the diagram?
initiation (of translation)
The initiator tRNA attaches at the ribosome's _____ site.
What does a bacterial RNA polymerase produce when it transcribes a protein-coding gene?
What is the function of a molecular chaperone?
To speed the correct folding of newly synthesized proteins
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