Bio 191 Ch. 17
Which of the following structures is needed for the translation initiation complex to form in eukaryotes? exon promoter 5′ AUG 3′ 5′ cap
5′ cap
Which of the following statements best supports the one gene-one enzyme hypothesis? Sickle-cell anemia results in normal hemoglobin. A mutation in a single gene can result in a defective protein. Alkaptonuria results when individuals lack multiple enzymes involved in the catalysis of homogentisic acid. Multiple antibody genes can code for different related proteins, depending on the splicing that takes place post-transcriptionally.
A mutation in a single gene can result in a defective protein.
Which of the following describes the most likely effect that a single base substitution in the middle of gene's sequence will have on the protein the gene encodes? All amino acids following the substitution would be affected because the reading frame would be altered. There would be no change because the genetic code is ambiguous. A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change. The protein would be shorter because the correct tRNA would not be able to interact with the ribosome.
A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change.
Which of the following processes correctly describes alternative RNA splicing? It is a mechanism for increasing the rate of translation. It can allow the production of proteins of different sizes and functions from a single mRNA. It increases the rate of transcription. It can allow the production of similar proteins from different RNAs.
It can allow the production of proteins of different sizes and functions from a single mRNA.
Which of the following statements correctly describes the function of a signal peptide? It helps target a protein to the ER. It signals the initiation of transcription. It terminates translation of messenger RNA. It directs an mRNA molecule into the lumen of the ER.
It helps target a protein to the ER.
Which of the following statements correctly describes a ribozyme? It is a catalyst that uses RNA as a substrate. It is an enzyme that synthesizes RNA as part of the transcription process. It is an RNA with catalytic activity. It is an enzyme that catalyzes the association between the large and small ribosomal subunits.
It is an RNA with catalytic activity.
Which of the following characteristics allows the CRISPR Cas9 enzyme to be an effective way to generate mutations that block the function of a specific protein (knock out)? It's function is regulated by a complementary guide RNA. It forms a complex with DNA. It makes double stranded breaks in DNA throughout the genome. It removes random DNA bases.
It's function is regulated by a complementary guide RNA.
Which of the following best describes the redundancy in the genetic code? The genetic code is universal (the same for all organisms). The genetic code is different for different domains of organisms. A single codon can specify the addition of more than one amino acid. More than one codon can specify the addition of the same amino acid.
More than one codon can specify the addition of the same amino acid.
Which answer correctly compares prokaryotic and eukaryotic codons? Prokaryotic codons usually contain different bases than those of eukaryotes. Organisms utilize codons that are nearly universal among all organisms. Organism within a phylum share codons that are distinct from organisms in other phyla. Prokaryotic codons usually specify different amino acids than those of eukaryotes.
Organisms utilize codons that are nearly universal among all organisms.
Which of the following processes occurs as part of transcription? proteins are synthesized DNA is replicated mRNA attaches to ribosomes RNA is synthesized
RNA is synthesized
In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein? RNA polymerase I RNA polymerase III RNA polymerase II primase
RNA polymerase II
Which of the following is most likely to occur if a researcher removes the 5′ cap and poly-A tail of an mRNA and inserts the mRNA molecule into a eukaryotic cell? The cell will add a new poly-A tail to the mRNA. The mRNA will be quickly converted into a ribosomal subunit. The mRNA will attaches to a ribosome and be translated, but more slowly. The molecule will be degraded by enzymes.
The molecule will be degraded by enzymes.
Which of the following statements is the most current description of a gene? a DNA sequence that is expressed to form a functional RNA or polypeptide product a unit of heredity that causes formation of a phenotypic characteristic a DNA subunit that codes for a single complete protein a discrete unit of hereditary information that consists of a sequence of amino acids
a DNA sequence that is expressed to form a functional RNA or polypeptide product
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the result of this type of mutation? a base-pair substitution a polypeptide missing its N-terminus a polypeptide missing an amino acid a frameshift mutation
a polypeptide missing an amino acid
Translation termination occurs when a ribosome interacts with which of the following structures? the poly-A tail a stop codon the end of the mRNA molecule. the 5′ cap
a stop codon
Post-translational modifications of proteins may include which of the following processes? synthesis of peptide bonds addition of a 5′ cap removal of introns addition of carbohydrates to form a glycoprotein
addition of carbohydrates to form a glycoprotein
Jennifer Doudna discovered CRISPR-Cas9 due to its role in which of the following? protecting mammalian cells against DNA virus integration defending bacteria against bacteriophage infection promoting adaptation by generating random mutations strengthening a virus' ability to infect its host
defending bacteria against bacteriophage infection
Check Desktop Ch. 17 3 What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure? peptide bonding between amino acids ionic bonding between phosphates van der Waals interactions between hydrogen atoms hydrogen bonding between base pairs
hydrogen bonding between base pairs
Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome? enzymes rRNA tRNA mRNA
mRNA
Rank the following mutations with respect to their likelihood of affecting the structure of the polypeptide (from most likely to affect structure to least likely). 1.insertion mutation in the middle of an intron 2.deletion of 3 bases crossing an intron-exon border 3.substitution mutation at the third position of a codon 4.substitution mutation at the second position of a codon 4, 3, 2, 1 3, 4, 2, 1 1, 2, 4, 3 2, 3, 4, 1
2, 3, 4, 1
In eukaryotes which of the following is the first step in translation? the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA base pairing of activated methionine-tRNA to AUG of the messenger RNA binding of the larger ribosomal subunit to smaller ribosomal subunits the ribosome reaches a stop codon
the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA
A particular triplet of bases in the coding sequence of DNA is 5'-AAA-3'. The anticodon on the tRNA that binds the mRNA codon is ________. 5′-UUA-3′ 3′-UUU-5′ 5′-TTT-3′ 3′-AAA-5′
3′-AAA-5′
An mRNA molecule with the sequence 5′-CCG-ACG-3′is being read by a ribosome.During translation which of the following tRNA anticodons will be the first to productively bind with this mRNA? 3′-UGC-5′ 5′-GGC-3′ 3′-GGC-5′ 5′-UGC-3′
3′-GGC-5′
Check Desktop ch. 17 2 Refer to the figure. Which of the triplets below is a possible anticodon in a tRNA that transports proline to a ribosome? 3′-CCC-5′ 5′-CCG-3′ 3′-GGC-5′ 5′-GGT-3′
3′-GGC-5′
A particular triplet of bases in the template strand of DNA is 5′-AGT-3′. What would be the corresponding codon for the mRNA that is transcribed? 5′-AGT-3′ 3′-UCA-5′ 3′-ACU-5′ 5′-UCA-3′
3′-UCA-5′
Use this model of a eukaryotic primary transcript to answer the following question.E = exon and I = intron5′-UTR E1 I1 E2 I2 E3 I3 E4 UTR-3′If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced? 5′-UTR E1 E2 E3 E4 UTR-3′ 5′-E1 E2 E3 E4-3′ 5′-UTR I1 I2 I3 UTR-3′ 5′-E1 I1 E2 I2 E3 I3 E4-3′
5′-UTR E1 E2 E3 E4 UTR-3′
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true? Different organisms have different types of amino acids. A gene from an organism can theoretically be expressed by any other organism. DNA was the first genetic material. The same codons in different organisms translate into different amino acids.
A gene from an organism can theoretically be expressed by any other organism.
During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon? E site the large ribosomal subunit P site A site
A site
Which of the following processes will occur at the exposed 3′ end of a tRNA molecule? An amino acid will bind covalently. The small and large subunits of the ribosome will attach to the 3" end. The 5′ cap of the mRNA will bind covalently. The single stranded nucleotides (ACCA) will be removed to stabilize the tRNA.
An amino acid will bind covalently.
Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur? Enzymes are made of DNA, and affected individuals lack DNA polymerase. Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes. Certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors. Metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.
Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.
What is the function of the release factor during translation in eukaryotes? It releases the ribosome from the ER to allow polypeptides into the cytosol. It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. It supplies a source of energy for termination of translation. It binds to the stop codon in the A site in place of a tRNA.
It binds to the stop codon in the A site in place of a tRNA.
Which of the following statements describes the effect of a nonsense mutation on a gene? It changes only one amino acid in the encoded protein. It alters the reading frame of the mRNA. It has no effect on the amino acid sequence of the encoded protein. It introduces a premature stop codon into the mRNA.
It introduces a premature stop codon into the mRNA.
Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes? It sets the reading frame of the mRNA during translation. It is the recognition site for ribosomal binding during translation. It is the recognition site for ribosomal binding during transcription. It is the recognition site for the binding of a specific transcription factor.
It is the recognition site for the binding of a specific transcription factor.
Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell? Its signal sequence must target it to the ER. Its signal sequence must be cleaved off as the polypeptide enters the ER. Its signal sequence must target it to the plasma membrane. It must be translated by a ribosome that remains free within the cytosol.
Its signal sequence must target it to the ER.
Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer that accomplishes this task in eukaryotes? Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place. Transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place. DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis. RNA polymerase transfers information from the nucleus to tRNA synthase in the cytoplasm, where protein synthesis takes place.
Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place.
Check Desktop Ch. 17 1: What amino acid sequence will be generated based on the following mRNA codon sequence?5′-AUG-UCU-UCG-UUA-UCC-UUG-3′ Met-Ser-Leu-Ser-Leu-Ser Met-Glu-Arg-Arg-Glu-Leu Met-Arg-Glu-Arg-Glu-Arg Met-Ser-Ser-Leu-Ser-Leu
Met-Ser-Ser-Leu-Ser-Leu
If a bacteria contained a mutant aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA which of the following would occur? Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU. The ribosome will skip a codon every time a UUU is encountered. The cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons. None of the proteins in the cell will contain phenylalanine.
Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
Which of the following statements best describes the termination of transcription in prokaryotes? RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase. Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome and releases. RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
Which of the following statements about RNA processing is correct? A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus. RNA splicing can be catalyzed by tRNA. Ribozymes may function in RNA splicing. Exons are removed before mRNA leaves the nucleus.
Ribozymes may function in RNA splicing.
Which of the following characteristics of gene expression is shared by eukaryotic and prokaryotic cells? Signal sequences are needed for the production of membrane proteins. Transcription of an mRNA is temporally separated from its translation. Ribosomes attach to the plasma membrane when producing secreted proteins. Translation occurs before transcription.
Signal sequences are needed for the production of membrane proteins.
Two mRNAs (mRNA X and mRNA Y) are synthesized with the same exon sequences but poly-A tails of very different lengths. mRNA X is 7,500 bases long. mRNA Y is 6,900 bases long. The mRNA's are added to separate in vitro translation mixtures containing radioactive methionine and the reactions are allowed to proceed for 30 minutes. When the mixtures are analyzed which of the following outcomes will most likely occur? The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture. The radioactive proteins in the mRNA X mixture will be larger in size than those in the mRNA Y mixture. The mRNA X mixture will contain radioactive proteins but the mRNA Y mixture will not. The radioactive proteins in the mRNA X mixture will begin with methionine while those in the mRNA Y mixture will not.
The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture.
Which of the following best explains the observation that in bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs? The rules for base pairing between the third base of a codon and tRNA are flexible. Many codons are never used, so the tRNAs that recognize them are dispensable. Some tRNAs have anticodons that recognize four or more different codons. The DNA codes 61 tRNAs, but some are destroyed after transcription.
The rules for base pairing between the third base of a codon and tRNA are flexible.
Which of the following statements is true about protein synthesis in prokaryotes? Translation can begin while transcription is still in progress. Translation requires no initiation or elongation factors. Protein targeting to cellular organelles requires recognition of signal sequences. Extensive RNA processing is required before transcripts can be translated.
Translation can begin while transcription is still in progress.
Which of the following changes in an exon is most likely to result in a nonfunctional protein product? a base-pair deletion a codon deletion an addition of three nucleotides a substitution in the last base of a codon
a base-pair deletion
A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following? an amino acid substitution at the active site of an enzyme an amino acid substitution that alters the tertiary structure of the protein a stop codon a codon that specifies the same amino acid as the original codon
a codon that specifies the same amino acid as the original codon
While characterizing an error-prone organism, researchers found that each of the following types of mutations occurred immediately downstream of the translation start site. Which type of mutation is likely to have the most serious effect on the function of the polypeptide product? a deletion of a codon a deletion of two nucleotides a substitution of the first nucleotide of a GGG codon a substitution of the third nucleotide in an ACC codon
a deletion of two nucleotides
Using the CRISPR-Cas9 system to correct a genetic defect in a mouse brings with it which of the following risks? decreasing the animal's ability to repair other mutations introducing CRISPR-Cas9 gene into the animal's genome increasing the animal's susceptibility to bacteriophage infection altering non-target mouse genes needed for cell function
altering non-target mouse genes needed for cell function
Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________. attachment of amino acid's carboxyl group with the amine of the next amino acid. binding of ribosomes to the mRNA attachment of amino acids to tRNAs binding of the anticodon to small subunit of the ribosome
attachment of amino acids to tRNAs
RNA is single stranded, can hydrogen-bond with other nucleic acids, and has functional groups that can function in catalysis. These characteristics support that RNA could have which of the following cellular roles? tagging proteins for degradation by lysosomes forming scaffolds for ribosome attachment targeting proteins for secretion forming peptide bonds
forming peptide bonds
A section of DNA has the base sequence shown in #1. A mutation in this DNA strand results in the base sequence shown in #2. What type of mutation does this change represent?#15' - AGCGTTACCGT-3'#25'-AGGCGTTACCGT-3' a point mutation a silent mutation a missense mutation frameshift mutation
frameshift mutation
According to the central dogma, which of the following intermediate molecules correctly completes the flow chart describing the flow of information in a cell blank?DNA → ________ → Proteins enzymes mRNA rRNA tRNA
mRNA
Which of the following molecular structures contains codons? mRNA tRNA a protein rRNA
mRNA
Which of the following molecules directly participates in the process of translation? mRNA, tRNA, and rRNA mRNA, tRNA, and DNA mRNA, DNA, and rRNA mRNA, tRNA, DNA, and rRNA
mRNA, tRNA, and rRNA
Which of the following processes occurs in prokaryotes but not in eukaryotes? simultaneous transcription and translation of the same mRNA removing introns from pre-RNA translocation into the ER translation in the absence of a ribosome
simultaneous transcription and translation of the same mRNA
Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA? the primary transcript is smaller than the mRNA the primary transcript is the same size as the mRNA the primary transcript is larger than the mRNA both the primary transcript and mRNA contain introns
the primary transcript is larger than the mRNA
Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA? the primary transcript and the mRNA both contain introns the primary transcript is the same size as the mRNA the primary transcript is larger than the mRNA the primary transcript is smaller than the mRNA
the primary transcript is the same size as the mRNA
Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation? the complementary binding of DNA with RNA the three-base sequence of mRNA the base sequence at the tRNA 5′ end the amino acetyl tRNA synthase used
the three-base sequence of mRNA
In the structure of many eukaryotic genes, individual exons parallel which of the following? the various domains of the protein product the number of start sites for transcription the sequence of the intron that immediately precedes each exon the number of polypeptides making up the functional protein
the various domains of the protein product
Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase? aminoacyl-tRNA synthetase anticodons ribosomes and tRNA transcription factors
transcription factors