Bio 17

25) Which of the following processes correctly describes alternative RNA splicing? A) It is a mechanism for increasing the rate of translation. B) It can allow the production of proteins of different sizes and functions from a single mRNA. C) It can allow the production of similar proteins from different RNAs. D) It increases the rate of transcription.

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

23) Which of the following statements correctly describes a ribozyme? A) It is a catalyst that uses RNA as a substrate. B) It is an RNA with catalytic activity. C) It is an enzyme that catalyzes the association between the large and small ribosomal subunits. D) It is an enzyme that synthesizes RNA as part of the transcription process.

B) It is an RNA with catalytic activity.

11) Which of the following processes occurs as part of transcription? A) DNA is replicated B) RNA is synthesized C) proteins are synthesized D) mRNA attaches to ribosomes

B) RNA is synthesized

50) Translation termination occurs when a ribosome interacts with which of the following structures? A) the end of the mRNA molecule. B) a stop codon C) the 5′ cap D) the poly-A tail

B) a stop codon

49) Which of the following structures is needed for the translation initiation complex to form in eukaryotes? A) promoter B) exon C) 5′ cap D) 5′ AUG 3′

C) 5′ cap

26) In the structure of many eukaryotic genes, individual exons parallel which of the following? A) the sequence of the intron that immediately precedes each exon B) the number of polypeptides making up the functional protein C) the various domains of the protein product D) the number of start sites for transcription

C) the various domains of the protein product

21) Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase? A) anticodons B) ribosomes and tRNA C) transcription factors D) aminoacyl-tRNA synthetase

C) transcription factors

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

D) 3′-AAA-5′

44) Use the figure to answer the question. Which codon on the mRNA strand codes for the amino acid carried by the aminoacyl-tRNA represented in the figure? A) 5′-UGG-3′ B) 3′-GUG-5′ C) 5′-GUA-3′ D) 5′-UUC-3′

D) 5′-UUC-3′

1) Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur? A) Metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies. 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) Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

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

4) Use the figure to answer the question. I----X----II----Y-----III The figure shows a simple metabolic pathway. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? A) 2 B) 3 C) 5 D) It cannot be determined from the information provided.

A) 2

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

A) 3′-GGC-5′

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

A) 3′-UCA-5′

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? A) A gene from an organism can theoretically be expressed by any other organism. B) DNA was the first genetic material. C) The same codons in different organisms translate into different amino acids. D) Different organisms have different types of amino acids.

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

9) Which of the following statements best supports the one gene-one enzyme hypothesis? A) A mutation in a single gene can result in a defective protein. B) Alkaptonuria results when individuals lack multiple enzymes involved in the catalysis of homogentisic acid. C) Sickle-cell anemia results in normal hemoglobin. D) Multiple antibody genes can code for different related proteins, depending on the splicing that takes place post-transcriptionally.

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

45) Which of the following processes will occur at the exposed 3′ end of a tRNA molecule? A) An amino acid will bind covalently. B) The single-stranded nucleotides (ACCA) will be removed to stabilize the tRNA. C) The small and large subunits of the ribosome will attach to the 3" end. D) The 5′ cap of the mRNA will bind covalently.

A) An amino acid will bind covalently.

40) What is the function of the release factor during translation in eukaryotes? A) It binds to the stop codon in the A site in place of a tRNA. B) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. C) It supplies a source of energy for termination of translation. D) It releases the ribosome from the ER to allow polypeptides into the cytosol.

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

22) Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes? A) It is the recognition site for the binding of a specific transcription factor. B) It sets the reading frame of the mRNA during translation. C) It is the recognition site for ribosomal binding during translation. D) It is the recognition site for ribosomal binding during transcription.

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

55) Which of the following changes in an exon is most likely to result in a nonfunctional protein product? A) a base-pair deletion B) an addition of three nucleotides C) a substitution in the last base of a codon D) a codon deletion

A) a base-pair deletion

46) Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell? A) It must be translated by a ribosome that remains free within the cytosol. B) Its signal sequence must target it to the ER. C) Its signal sequence must be cleaved off as the polypeptide enters the ER. D) Its signal sequence must target it to the plasma membrane.

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

14) 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? A) DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis. B) Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place. C) RNA polymerase transfers information from the nucleus to tRNA synthase in the cytoplasm, where protein synthesis takes place. D) Transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place.

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

36) 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? 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.

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

20) In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein? A) RNA polymerase I B) RNA polymerase II C) RNA polymerase III D) primase

B) RNA polymerase II

19) Which of the following statements best describes the termination of transcription in prokaryotes? 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) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome and releases. D) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

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

30) Which of the following statements about RNA processing is correct? A) Exons are removed before mRNA leaves the nucleus. B) Ribozymes may function in RNA splicing. C) RNA splicing can be catalyzed by tRNA. D) A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus.

B) Ribozymes may function in RNA splicing.

37) 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? 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 61 tRNAs, but some are destroyed after transcription.

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

52) Which of the following statements is true about protein synthesis in prokaryotes? A) Extensive RNA processing is required before transcripts can be translated. B) Translation can begin while transcription is still in progress. C) Protein targeting to cellular organelles requires recognition of signal sequences. D) Translation requires no initiation or elongation factors.

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

53) 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) 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

B) a deletion of two nucleotides

43) Use the figure to answer the question. What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure? A) ionic bonding between phosphates B) hydrogen bonding between base pairs C) van der Waals interactions between hydrogen atoms D) peptide bonding between amino acids

B) hydrogen bonding between base pairs

12) Which of the following molecular structures contains codons? A) a protein B) mRNA C) tRNA D) rRNA

B) mRNA

41) Use the following information to answer the question. 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. tRNA Anticodon Amino Acid GGC CGU UGC CCG ACG CGG Proline Alanine Threonine Glycine Cysteine Alanine Which of the following dipeptides will form from this mRNA? A) cysteine-alanine B) proline-threonine C) glycine-cysteine D) alanine-alanine

B) proline-threonine

18) Which of the following processes occurs in prokaryotes but not in eukaryotes? A) removing introns from pre-RNA B) simultaneous transcription and translation of the same mRNA C) translation in the absence of a ribosome D) translocation into the ER

B) simultaneous transcription and translation of the same mRNA

31) Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA? A) the primary transcript is the same size as the mRNA B) the primary transcript is larger than the mRNA C) the primary transcript is smaller than the mRNA D) both the primary transcript and mRNA contain introns

B) the primary transcript is larger than the mRNA

8) The following question refers to this table of codons. Refer to the figure. Which of the triplets below is a possible anticodon in a tRNA that transports proline to a ribosome? A) 5′-GGT-3′ B) 5′-CCG-3′ C) 3′-GGC-5′ D) 3′-CCC-5′

C) 3′-GGC-5′

29) 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? 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′-E1 I1 E2 I2 E3 I3 E4-3′

C) 5′-UTR E1 E2 E3 E4 UTR-3′

48) During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon? A) E site B) P site C) A site D) the large ribosomal subunit

C) A site

39) Which of the following statements correctly describes the function of a signal peptide? A) It directs an mRNA molecule into the lumen of the ER. B) It terminates translation of messenger RNA. C) It helps target a protein to the ER. D) It signals the initiation of transcription.

C) It helps target a protein to the ER.

54) Which of the following statements describes the effect of a nonsense mutation on a gene? A) It changes only one 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.

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

28) 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? A) The mRNA X mixture will contain radioactive proteins but the mRNA Y mixture will not. B) The radioactive proteins in the mRNA X mixture will be larger in size than those in the mRNA Y mixture. 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 begin with methionine while those in the mRNA Y mixture will not.

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

56) 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) a base-pair substitution B) a frameshift mutation C) a polypeptide missing an amino acid D) a polypeptide missing its N-terminus

C) a polypeptide missing an amino acid

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

C) mRNA

16) Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome? A) enzymes B) rRNA C) mRNA D) tRNA

C) mRNA

47) Which of the following molecules directly participates in the process of translation? A) mRNA, tRNA, DNA, and rRNA B) mRNA, DNA, and rRNA C) mRNA, tRNA, and rRNA D) mRNA, tRNA, and DNA

C) mRNA, tRNA, and rRNA

5) Use the figure to answer the question. I----X----II----Y-----III------Z------IV 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)? A) nutrient A only B) nutrient B only C) nutrients A and B only D) nutrients B, C, and D only

C) nutrients A and B only

6) Use the figure to answer the question. I----X----II----Y-----III------Z------IV 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? A) nutrient A only B) nutrient C only C) nutrients A and C only D) nutrients B and D only

C) nutrients A and C only

10) Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation? A) the base sequence at the tRNA 5′ end B) the amino acetyl tRNA synthase used C) the three-base sequence of mRNA D) the complementary binding of DNA with RNA

C) the three-base sequence of mRNA

7) The following question refers to this table of codons. What amino acid sequence will be generated 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

D) Met-Ser-Ser-Leu-Ser-Leu

13) Which of the following best describes the redundancy in the genetic code? A) A single codon can specify the addition of more than one amino acid. B) The genetic code is different for different domains of organisms. C) The genetic code is universal (the same for all organisms). D) More than one codon can specify the addition of the same amino acid.

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

17) Which answer correctly compares prokaryotic and eukaryotic codons? A) Prokaryotic codons usually contain different bases than those of eukaryotes. B) Prokaryotic codons usually specify different amino acids 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.

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

33) Which of the following characteristics of gene expression is shared by eukaryotic and prokaryotic cells? A) Translation occurs before transcription. B) Transcription of an mRNA is temporally separated from its translation. C) Ribosomes attach to the plasma membrane when producing secreted proteins. D) Signal sequences are needed for the production of membrane proteins.

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

27) 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? A) The mRNA will be quickly converted into a ribosomal subunit. B) The cell will add a new poly-A tail to the mRNA. C) The mRNA will attaches to a ribosome and be translated, but more slowly. D) The molecule will be degraded by enzymes.

D) The molecule will be degraded by enzymes.

51) Post-translational modifications of proteins may include which of the following processes? A) removal of introns B) addition of a 5′ cap C) synthesis of peptide bonds D) addition of carbohydrates to form a glycoprotein

D) addition of carbohydrates to form a glycoprotein

35) Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________. A) binding of ribosomes to the mRNA B) binding of the anticodon to small subunit of the ribosome C) attachment of amino acid's carboxyl group with the amine of the next amino acid. D) attachment of amino acids to tRNAs

D) attachment of amino acids to tRNAs

24) 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? A) tagging proteins for degradation by lysosomes B) targeting proteins for secretion C) forming scaffolds for ribosome attachment D) forming peptide bonds

D) forming peptide bonds

32) Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA? A) the primary transcript is larger than the mRNA B) the primary transcript is smaller than the mRNA C) the primary transcript and the mRNA both contain introns D) the primary transcript is the same size as the mRNA

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

38) In eukaryotes which of the following is the first step in translation? A) base pairing of activated methionine-tRNA to AUG of the messenger RNA B) binding of the larger ribosomal subunit to smaller ribosomal subunits C) the ribosome reaches a stop codon D) the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

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