Bio 211 Chapter 17

Which of the following is true of RNA processing? 1) _______

A) nucleotides are added at both ends of the RNA

B) exons are cut out before mRNA leaves the nucleus

C) RNA splicing adds a poly-A tail to the mRNA

D) ribozymes may function in the addition of a 5' cap

nucleotides are added at both ends of the RNA

Which of the following statements correctly describes the function of a signal peptide? 2) _______

A) It signals the initiation of transcription.

B) It terminates translation of messenger RNA.

C) It helps target a protein to the ER.

D) It directs an mRNA molecule into the lumen of the ER.

It helps target a protein 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? 3)

_______

A) RNA polymerase transfers information from the nucleus to tRNA synthase in the cytoplasm, where protein synthesis takes place.

B) DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis.

C) Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place.

D) Transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place.

Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place.

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true? 4) _______

A) The same codons in different organisms translate into different amino acids.

B) A gene from an organism can theoretically be expressed by any other organism.

C) Different organisms have different types of amino acids.

D) DNA was the first genetic material.

A gene from an organism can theoretically be expressed by any other organism.

A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following? 5) _______

A) an amino acid substitution at the active site of an enzyme

B) an amino acid substitution that alters the tertiary structure of the protein

C) a stop codon

D) a codon that specifies the same amino acid as the original codon

a codon that specifies the same amino acid as the original codon

Which of the following statements about RNA processing is correct? 6) _______

A) Exons are removed before mRNA leaves the nucleus.

B) RNA splicing can be catalyzed by tRNA.

C) A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus.

D) Ribozymes may function in RNA splicing.

Ribozymes may function in RNA splicing.

Which component is directly involved in translation? 7) _______

A) RNA polymerase B) spliceosome

C) DNA D) ribosome

ribosome

In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?8) _______

A) RNA polymerase I B) RNA polymerase III

C) RNA polymerase II D) primase

RNA polymerase II

Which of the following processes will occur at the exposed 3′ end of a tRNA molecule? 9) _______

A) The small and large subunits of the ribosome will attach to the 3" end.

B) An amino acid will bind covalently.

C) The 5′ cap of the mRNA will bind covalently.

D) The single stranded nucleotides (ACCA) will be removed to stabilize the tRNA.

An amino acid will bind covalently.

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? 10) ______

A) The molecule will be degraded by enzymes.

B) The cell will add a new poly-A tail to the mRNA.

C) The mRNA will be quickly converted into a ribosomal subunit.

D) The mRNA will attaches to a ribosome and be translated, but more slowly.

The molecule will be degraded by enzymes.

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? 11) ______

A) The protein would be shorter because the correct tRNA would not be able to interact with the ribosome.

B) There would be no change because the genetic code is ambiguous.

C) All amino acids following the substitution would be affected because the reading frame would be altered.

D) A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change.

A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change.

Translation termination occurs when a ribosome interacts with which of the following structures? 12) ______

A) the 5′ cap B) the end of the mRNA molecule.

C) a stop codon D) the poly-A tail

a stop codon

The anticodon of a particular tRNA molecule is ________. 13) ______

A) complementary to the corresponding mRNA codon

B) complementary to the corresponding triplet in rRNA

C) catalytic, making the tRNA a ribozyme

D) the part of tRNA that bonds to a specific amino acid

complementary to the corresponding mRNA codon

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

14) ______

A) tRNA B) enzymes C) mRNA D) rRNA

mRNA

Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________. 15)

______

A) attachment of amino acid's carboxyl group with the amine of the next amino acid.

B) attachment of amino acids to tRNAs

C) binding of ribosomes to the mRNA

D) binding of the anticodon to small subunit of the ribosome

attachment of amino acids to tRNAs

Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase? 16) ______

A) aminoacyl-tRNA synthetase B) anticodons

C) transcription factors D) ribosomes and tRNA

transcription factors

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? 17)

______

A) 3′-GGC-5′ B) 5′-UGC-3′ C) 5′-GGC-3′ D) 3′-UGC-5′

3′-GGC-5′

Which of the following statements correctly describes a ribozyme? 18) ______

A) It is an enzyme that synthesizes RNA as part of the transcription process.

B) It is a catalyst that uses RNA as a substrate.

C) It is an enzyme that catalyzes the association between the large and small ribosomal subunits.

D) It is an RNA with catalytic activity.

It is an RNA with catalytic activity.

Which of the following statements describes the effect of a nonsense mutation on a gene? 19) ______

A) It alters the reading frame of the mRNA.

B) It introduces a premature stop codon into the mRNA.

C) It changes only one amino acid in the encoded protein.

D) It has no effect on the amino acid sequence of the encoded protein.

It introduces a premature stop codon into the mRNA.

Which of the following processes occurs as part of transcription? 20) ______

A) DNA is replicated B) mRNA attaches to ribosomes

C) RNA is synthesized D) proteins are synthesized

RNA is synthesized

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 ________. 21) ______

A) 3′-UUU-5′ B) 5′-UUA-3′ C) 5′-TTT-3′ D) 3′-AAA-5′

3′-AAA-5′

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 22) ______

A) 2, 3, 4, 1 B) 4, 3, 2, 1 C) 3, 4, 2, 1 D) 1, 2, 4, 3

2, 3, 4, 1

Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation? 23) ______

A) the amino acetyl tRNA synthase used

B) the complementary binding of DNA with RNA

C) the base sequence at the tRNA 5′ end

D) the three-base sequence of mRNA

the three-base sequence of mRNA

What is the function of the release factor during translation in eukaryotes? 24) ______

A) It binds to the stop codon in the A site in place of a tRNA.

B) It releases the ribosome from the ER to allow polypeptides into the cytosol.

C) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond.

D) 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.

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)?

A) It removes random DNA bases.

B) It forms a complex with DNA.

C) It makes double stranded breaks in DNA throughout the genome.

D) It’s function is regulated by a complementary guide RNA.

It’s function is regulated by a complementary guide RNA.

In the structure of many eukaryotic genes, individual exons parallel which of the following? 26) ______

A) the various domains of the protein product

B) the number of start sites for transcription

C) the number of polypeptides making up the functional protein

D) the sequence of the intron that immediately precedes each exon

the various domains of the protein product

Which of the following characteristics of gene expression is shared by eukaryotic and prokaryotic cells? 27) ______

A) Transcription of an mRNA is temporally separated from its translation.

B) Signal sequences are needed for the production of membrane proteins.

C) Ribosomes attach to the plasma membrane when producing secreted proteins.

D) Translation occurs before transcription.

Signal sequences are needed for the production of membrane proteins.

What amino acid sequence will be generated based on the following mRNA codon sequence?

5′-AUG-UCU-UCG-UUA-UCC-UUG-3′ 28) ______

A) Met-Ser-Leu-Ser-Leu-Ser B) Met-Ser-Ser-Leu-Ser-Leu

C) Met-Glu-Arg-Arg-Glu-Leu D) Met-Arg-Glu-Arg-Glu-Arg

Met-Ser-Ser-Leu-Ser-Leu

Jennifer Doudna discovered CRISPR-Cas9 due to its role in which of the following? 29) ______

A) strengthening a virus' ability to infect its host

B) defending bacteria against bacteriophage infection

C) protecting mammalian cells against DNA virus integration

D) promoting adaptation by generating random mutations

defending bacteria against bacteriophage infection

In eukaryotic cells, transcription cannot begin until ________. 30) ______

A) the 5' caps are removed from the mRNA

B) the DNA introns are removed from the template

C) the two DNA strands have completely separated and exposed the promoter

D) several transcription factors have bound to the promoter

several transcription factors have bound to the promoter

Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA? 31) ______

A) the primary transcript is the same size as the mRNA

B) the primary transcript and the mRNA both contain introns

C) the primary transcript is larger than the mRNA

D) the primary transcript is smaller than the mRNA

the primary transcript is the same size as the mRNA

Which of the following molecules directly participates in the process of translation? 32) ______

A) mRNA, DNA, and rRNA B) mRNA, tRNA, DNA, and rRNA

C) mRNA, tRNA, and rRNA D) mRNA, tRNA, and DNA

mRNA, tRNA, and rRNA

Which answer correctly compares prokaryotic and eukaryotic codons? 33) ______

A) Prokaryotic codons usually specify different amino acids than those of eukaryotes.

B) Prokaryotic codons usually contain different bases than those of eukaryotes.

C) Organism within a phylum share codons that are distinct from organisms in other phyla.

D) Organisms utilize codons that are nearly universal among all organisms.

Organisms utilize codons that are nearly universal among all organisms.

Which of the following statements is true about protein synthesis in prokaryotes? 34) ______

A) Translation can begin while transcription is still in progress.

B) Extensive RNA processing is required before transcripts can be translated.

C) Protein targeting to cellular organelles requires recognition of signal sequences.

D) Translation requires no initiation or elongation factors.

Translation can begin while transcription is still in progress.

Refer to the metabolic pathway illustrated. If I, II, III, and IV are all required for growth, a bacterial strain that does not make enzyme X would be able to grow on medium supplemented with which of the following nutrient(s)? 35) ______

A) nutrient A only B) nutrient B only

C) nutrients A and B only D) nutrients B, C, and D only

nutrients A and B only

Which of the following processes occurs in prokaryotes but not in eukaryotes? 36) ______

A) translocation into the ER

B) removing introns from pre-RNA

C) simultaneous transcription and translation of the same mRNA

D) translation in the absence of a ribosome

simultaneous transcription and translation of the same mRNA

Which codon on the mRNA strand codes for the amino acid carried by the aminoacyl-tRNA represented in the figure? 37)

______

A) 3′-GUG-5′ B) 5′-GUA-3′ C) 5′-UUC-3′ D) 5′-UGG-3′

5′-UUC-3′

Which of the following is true of a codon? 38) ______

A) It is the basic unit of protein structure.

B) It never codes for the same amino acid as another codon.

C) It can be either in DNA or in RNA.

D) It can code for more than one amino acid.

It can be either in DNA or in RNA.

What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure? 39) ______

A) hydrogen bonding between base pairs

B) peptide bonding between amino acids

C) ionic bonding between phosphates

D) van der Waals interactions between hydrogen atoms

hydrogen bonding between base pairs

During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon? 40) ______

A) A site B) E site

C) P siteD) the large ribosomal subunit

A site

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? 41) ______

A) tagging proteins for degradation by lysosomes

B) targeting proteins for secretion

C) forming peptide bonds

D) forming scaffolds for ribosome attachment

forming peptide bonds

Which of the following best describes the redundancy in the genetic code? 42) ______

A) The genetic code is different for different domains of organisms.

B) More than one codon can specify the addition of the same amino acid.

C) The genetic code is universal (the same for all organisms).

D) 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.

Which of the following mutations would be most likely to have a harmful effect on an organism? 43) ______

A) a single nucleotide deletion in the middle of an intron

B) a single nucleotide insertion downstream of, and close to, the start of the coding sequence

C) a deletion of three nucleotides near the middle of a gene

D) a single nucleotide deletion near the end of the coding sequence

a single nucleotide insertion downstream of, and close to, the start of the coding sequence

The figure shows a simple metabolic pathway. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? 44) ______

A) 3

B) 2

C) 5

D) It cannot be determined from the information provided.

2

Refer to the metabolic pathway illustrated. If I, II, III and IV are all required for growth, a bacterial strain that does not make enzyme Y would be able to grow on medium supplemented with which of the following compounds? 45) ______

A) nutrient A only B) nutrient C only

C) nutrients A and C only D) nutrients B and D only

nutrients A and C only

Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell?46) ______

A) It must be translated by a ribosome that remains free within the cytosol.

B) Its signal sequence must target it to the plasma membrane.

C) Its signal sequence must be cleaved off as the polypeptide enters the ER.

D) Its signal sequence must target it to the ER.

Its signal sequence must target it to the ER.

Which of the following statements best describes the termination of transcription in prokaryotes? 47) ______

A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.

B) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome and releases.

C) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

D) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

In eukaryotes which of the following is the first step in translation? 48) ______

A) the ribosome reaches a stop codon

B) base pairing of activated methionine-tRNA to AUG of the messenger RNA

C) the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

D) binding of the larger ribosomal subunit to smaller ribosomal subunits

the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

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? 49) ______

A) None of the proteins in the cell will contain phenylalanine.

B) The ribosome will skip a codon every time a UUU is encountered.

C) Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

D) The cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.

Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

Which of the following statements is the most current description of a gene? 50) ______

A) a discrete unit of hereditary information that consists of a sequence of amino acids

B) a DNA sequence that is expressed to form a functional RNA or polypeptide product

C) a DNA subunit that codes for a single complete protein

D) a unit of heredity that causes formation of a phenotypic characteristic

a DNA sequence that is expressed to form a functional RNA or polypeptide product

Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes?

51) ______

A) It is the recognition site for ribosomal binding during translation.

B) It is the recognition site for ribosomal binding during transcription.

C) It is the recognition site for the binding of a specific transcription factor.

D) It sets the reading frame of the mRNA during translation.

It is the recognition site for the binding of a specific transcription factor.

Which of the following structures is needed for the translation initiation complex to form in eukaryotes? 52) ______

A) promoter B) 5′ cap C) exon D) 5′ AUG 3′

5’ cap

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? 53) ______

A) 3′-ACU-5′ B) 5′-UCA-3′ C) 3′-UCA-5′ D) 5′-AGT-3′

3′-UCA-5′

Which of the following statements best supports the one gene-one enzyme hypothesis? 54) ______

A) Sickle-cell anemia results in normal hemoglobin.

B) Multiple antibody genes can code for different related proteins, depending on the splicing that takes place post- transcriptionally.

C) Alkaptonuria results when individuals lack multiple enzymes involved in the catalysis of homogentisic acid.

D) A mutation in a single gene can result in a defective protein.

A mutation in a single gene can result in a defective protein.

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? 55) ______

A) Some tRNAs have anticodons that recognize four or more different codons.

B) Many codons are never used, so the tRNAs that recognize them are dispensable.

C) The DNA codes 61 tRNAs, but some are destroyed after transcription.

D) The rules for base pairing between the third base of a codon and tRNA are flexible.

The rules for base pairing between the third base of a codon and tRNA are flexible.

Which of the following molecular structures contains codons? 56) ______

A) mRNA B) rRNA C) tRNA D) a protein

mRNA

Use this model of a eukaryotic primary transcript to answer the following question.

E = exon and I = intron

5′-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? 57) ______

A) 5′-UTR I₁ I₂ I₃ UTR-3′B) 5′-E1 I₁ E₂ I₂ E₃ I₃ E₄-3′

C) 5′-UTR E₁ E₂ E₃ E₄ UTR-3′ D) 5′-E₁ E₂ E₃ E₄-3′

5′-UTR E₁ E₂ E₃ E₄ UTR-3′

Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur? 58) ______

A) Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

B) Enzymes are made of DNA, and affected individuals lack DNA polymerase.

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.

Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

Which of the following changes in an exon is most likely to result in a nonfunctional protein product? 59) ______

A) a codon deletion B) a base-pair deletion

C) a substitution in the last base of a codon D) an addition of three nucleotides

a base-pair deletion

An mRNA molecule with the sequence 5′-CCG-ACG-3′is being translated at a ribosome. The following charged transfer RNA molecules (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.

Which of the following dipeptides will form from this mRNA? 60) ______

A) alanine-alanine B) glycine-cysteine

C) proline-threonine D) cysteine-alanine

proline-threonine

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? 61) ______

A) a substitution of the third nucleotide in an ACC codon

B) a substitution of the first nucleotide of a GGG codon

C) a deletion of a codon

D) a deletion of two nucleotides

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? 62)

______

A) introducing CRISPR-Cas9 gene into the animal's genome

B) decreasing the animal's ability to repair other mutations

C) altering non-target mouse genes needed for cell function

D) increasing the animal's susceptibility to bacteriophage infection

altering non-target mouse genes needed for cell function

Using the figure identify a 5'→ 3' sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys. 63) ______

A) 5'-GAACCCCTT-3' B) 5'-CTTCGGGAA-3'

C) 5'-UUUCCCAAA-3' D) 5'-AAACCCUUU-3'

5'-CTTCGGGAA-3'

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? 64) ______

A) The radioactive proteins in the mRNA X mixture will begin with methionine while those in the mRNA Y mixture will not.

B) The mRNA X mixture will contain radioactive proteins but the mRNA Y mixture will not.

C) The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture.

D) 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 more radioactive proteins than the mRNA Y mixture.

Which of the following processes correctly describes alternative RNA splicing? 65) ______

A) It can allow the production of proteins of different sizes and functions from a single mRNA.

B) It can allow the production of similar proteins from different RNAs.

C) It increases the rate of transcription.

D) 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.

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?

66) ______

A) the primary transcript is smaller than the mRNA

B) both the primary transcript and mRNA contain introns

C) the primary transcript is the same size as the mRNA

D) the primary transcript is larger than the mRNA

the primary transcript is larger than the mRNA

Post-translational modifications of proteins may include which of the following processes? 67) ______

A) addition of carbohydrates to form a glycoprotein

B) synthesis of peptide bonds

C) removal of introns

D) addition of a 5′ cap

addition of carbohydrates to form a glycoprotein

Refer to the figure. Which of the triplets below is a possible anticodon in a tRNA that transports proline to a ribosome?68)

______

A) 5′-GGT-3′ B) 3′-GGC-5′ C) 3′-CCC-5′ D) 5′-CCG-3′

3′-GGC-5′

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?

#1 5' - AGCGTTACCGT-3'

#2 5'-AGGCGTTACCGT-3'

69) ______

A) a silent mutation B) frameshift mutation

C) a missense mutation D) a point mutation

frameshift mutation

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? 70) ______

A) a polypeptide missing its N-terminus B) a frameshift mutation

C) a base-pair substitution D) a polypeptide missing an amino acid

a polypeptide missing an amino acid

Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?

71) ______

A) tRNA B) mRNA C) rRNAD) enzymes

mRNA