Cell Bio Exam 2

63) The most common way gene expression is regulated in both prokaryotes and eukaryotes is through the— a. Control of gene transcription b. Control of gene translation c. Prevention of DNA uncoiling d. Breakdown of proteins formed in translation e. None of the above

A

59) What of the fate of mature mRNA in eukaryotes that has a premature stop codon 5' to EJC proteins bound to it in the cytoplasm: a) it has previously been given a 5' cap in the nucleus b) it has previously been given a poly-A tail in the nucleus c) It is translated d) It is not translated e) It is degraded f) It is bound in complex with Upf proteins

ABDEF

50) The sequence in prokaryotes that is recognized that defines where the ribosomes start translation is: a) The Kozak's consensus sequence b) The Shine-Dalgarno sequence c) The BRE d) The TATA Box e) The MTE f) The DPE g) The INR h) all of the above

B

58) What would be the likely consequence of an mRNA that lacks SR proteins bound to it during splicing: a) the 5' cap structure would not be added b) many exons could be lost during splicing c) the mRNA would not get a poly-A tail d) poly A binding proteins would not be able to the mRNA e) hnRNPs could not bind to the intron sequences

B

61) John has discovered a new organism that utilizes a single stranded DNA molecule for its genome. He believes that during differentiation of some of the organism's cells that its DNA is edited to remove some internal sequences. He tells Mary that he hypothesizes that the DNA splicing in this case occurs similar to eukaryotic mRNA splicing. She tells him that it is not likely that this is the case. Which of the following are valid and RELEVANT reasons why this is not the case: A) The organism has no snoRNPs that recognize sites to make modified nucleotides. B) She has sequenced the genome and there are no AG sequences in the genome. C) She has observed by electron microscopes and proved that there are no lariat-like structures in these cells. D) DNA can only form a double helix; it can't form other secondary structures, even if it is single stranded. E) DNA contains deoxyribose; there is no 2' hydroxyl group. F) There are no CPSF proteins in the organism. G) The organism does not have a DNA equivalent of snRNPs. H) all of the above are valid reasons why this organisms DNA splicing can't occur like eukaryotic mRNA splicing.

BCEG

57) Which of the following RNAs are extensively posttransciptional modified (i.e. have chemically modified sugars and nitrogenous bases): a. messenger mRNA (mRNA) b. ribosomal RNAs (rRNAs) c. small interfering RNAs (siRNAs) d. short hairpin RNAs (shRNAs) e. transfer RNAs (tRNAs) f. microRNAs (miRNAs) g. snRNAs h. snoRNA

BE

51) Which of the following sequences are responsible for binding to the general transcription factor that positions the RNA polymerase at the proper start site for transcription to begin a) The Kozak's consensus sequence b) The Shine-Dalgarno sequence c) The BRE d) The TATA Box e) The MTE f) The DPE g) The INR h) all of the above

C

53) Which of the following RNA(s) functions in the recognition of nucleotides that need to be modified in ribosomal RNAs (rRNAs)? a. Transfer RNAs (tRNAs) b. Small hairpin RNAs (shRNAs) c. Small nucleolar RNAs (snoRNAs) d. Small nuclear RNAs (snRNAs) e. Small interfering RNAs (siRNAs) f. MicroRNAs (miRNAs)

C

55) Which of the following is NOT part of the large eukaryotic complex that mediates transcription: a) the Mediator complex proteins b) transcriptional activators or repressors bound to enhancer sequences c) proteins bound to the Kozak consensus sequence d) TFIID bound to the TATA box e) the chromatin remodeling complex f) histone modifying enzymes

C

62) How can a single RNA transcript lead to the translation of different proteins? a. The same RNA transcript may contain one of several different 5' untranslated regions b. The same RNA transcript may contain one of several different caps c. The same RNA transcript may be spliced in several different ways d. The same RNA transcript may contain one of several different promoters e. The same RNA transcript may contain one of several different 3' untranslated regions

C

You have a segment of DNA that contains the following sequence: 5′-GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3′ 3′-CCTGATCTGTTATCCCTGGATCTCTAAGGCTTT-5′ You know that the RNA transcribed from this segment contains the following sequence: 5′-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAA-3′ Which of the following choices best describes how transcription occurs? (a) the top strand is the template strand; RNA polymerase moves (relative to this strand) from 5′ to 3′ (b) the top strand is the template strand; RNA polymerase moves (relative to this strand)from 3′ to 5′ (c) the bottom strand is the template strand; RNA polymerase moves (relative to this strand) from 5′ to 3′ (d) the bottom strand is the template strand; RNA polymerase moves (relative to this strand) from 3′ to 5′

d

54) What would be the likely consequence of an mRNA that does not get CPSF or CstF factors bound to the nascent mRNA: a) hnRNPs could not bind to the intron sequences b) the 5' cap structure would not be added c) many exons would be lost during splicing d) poly A binding proteins would not bind to the mRNA e) the mRNA would not get a poly-A tail

DE

60) Which of the following affect the ability of histone "writers" and "readers" to affect gene expression: a) monomethylation of threonine residues in histone tails b) dimethylation of threonine residues in histone tails c) trimethylation of threonine residues in histone tails d) monomethylation of lysine residues in histone tails e) dimethylation of lysine residues in histone tails f) trimethylation of lysine residues in histone tails a) modification of histone tails by lysine acetylation b) kinase phosphorylation of serine in histone tails g) all of the above

DEFAB

49) Which of the following sequences are bound by the general transcription factor TFIID? a) The Kozak's consensus sequence b) The Shine-Dalgarno sequence c) The BRE d) The TATA Box e) The MTE f) The DPE g) The INR h) all of the above

DEFG

56) The sequence in eukaryotes that is recognized that defines where the ribosomes start translation is: a) The BRE b) The TATA Box c) The MTE d) The DPE e) The INR f) The Kozak's consensus sequence g) The Shine-Dalgarno sequence h) all of the above

F

DNA replication takes place in which phase of the cell cycle: a) S b) G1 c) G2 d) M e) G0

a

Where or when does RNA capping at the 5' end of the transcript take place? A) as an RNA is being transcribed B) after RNA splicing C) once an RNA is released by RNA polymerase D) within the nuclear pore complex E) when an RNA exits the nucleus

a

Which amino acid will be on the tRNA that is the first to bind to the P site of the ribosome? (a) methionine (b) arginine (c) cysteine (d) valine (e) proline

a

During DNA replication, the single-strand DNA-binding (SSB) proteins ... A. are generally found more on the leading strand than the lagging strand. B. prevent the folding of the single-stranded DNA. C. bind to the polymerase, increasing its affinity for DNA. D. All of the above.

b

Eukaryotic 5' caps are made from which of the following: A. dATP. B. dGTP. C. 7-methyladenine D. 7-methylguanine E. 7-methylcytosine

b

The sequence of the coding strand of a DNA molecule (that is, the DNA strand that contains the codons specifying the protein sequence) is 5'-CGGATGCTTA-3'. What is the sequence of the RNA made from this DNA? a) 5'-UAAGCAUCCG-3' b) 5'-CGGATGCTTA-3' c) 5'-CGGAUGCUUA-3' d) 5'-GCCUACGAAU-3' e) 5'-TAAGCATCCG-3'

c

What best describes the histone code? a) there are different histones for each nucleosome. b) the kind of histones determine whether the DNA is expressed. c) writer and reader proteins covalently modify histones in certain DNA areas affecting mRNA expression. d) different histones are bound to the ribosome to interpret the RNA genetic code. e) histones are sets of 3 base pairs that code for each amino acid.

c

What characterizes the majority of DNA found in the nucleus of eukaryotic cells? a) it is found in the nucleolus b) chromosomes are unwound and loose in the nucleus c) it is attached to nuclear lamin proteins at the nuclear periphery d) it has little to no protein attached to it e) it is found in circular chromosomes

c

What would happen if you created a tRNA with an anticodon of 5-GAA-3 that is charged with methionine, and added this modified tRNA to a cell-free translation system that has all the normal components required for translating RNAs? (a) leucine would be incorporated into proteins at some positions where methionine should be (b) phenylalanine would be incorporated into proteins at some positions where methionine should be (c) methionine would be incorporated into proteins at some positions where phenylalanine should be (c) methionine would be incorporated into proteins at some positions where leucine should be (e) methionine would be incorporated into proteins at some positions where glutamine should be

c

Which if the following is generally true about exons and introns in a gene: a) exons are generally larger than introns; introns encode the amino acid sequence b) exons are generally smaller than introns; introns encode the amino acid sequence c) introns are generally larger than exons; exons encode the amino acid sequence d) introns are generally smaller than exons; exons encode the amino acid sequence e) introns are generally the same size as exons; introns encode the amino acid sequence

c

Which of the following chaperone in the cytoplasm is the first to bind unfolded polypeptides coming off the ribosome? A. HSP27. B. HSP90. C. HSP40. D. HSP60. E. HSP70.

c

Which of the following is true about the TATA box sequence: a) it specifies the start site for translation. b) it is recognized by TFIIH. c) it is the sequence that is first distorted during transcription. d) it is found 30 base pairs downstream of the transcription start site. e) it is recognized by TFIIB.

c

Which of the following polymerases does not require a template: a) RNA polymerase I b) Telomerase c) Poly A polymerase d) DNA primase e) DNA polymerase III

c

Which of the following statements about the genetic code is correct? a) All codons specify an amino acid. b) All amino acids are specified by more than one codon. c) Different codons can lead to insertion of the same amino acid. d) All codons specify more than one amino acid. e) The code is very different between organisms.

c

Which proteins binds to the splice junction sites and catalyze mRNA splicing? A. snRNPs. B. hnRNPs. C. SR proteins. D. EJC proteins. E. snoRNAs.

c

Prokaryotes have chromosomes that are circular in structure and lack what? a) sugar-phosphate backbone b) replication origin c) complementary base pairs d) telomeres e) DNA double helix

d

Proteins are synthesized from: a) nucleotides b) 5' to 3' c) 3' to 5' d) N-terminal to C-terminal e) C-terminal to N-terminal

d

Which enzyme synthesizes short RNA segments on the lagging strand that are then extended before ultimately being removed? A. DNA helicase. B. DNA polymerase. C. DNA ligase. D. DNA primase. E. Telomerase.

d

Which is the enzyme that makes a single stand cut of the phosphodiester bonds in DNA: A. DNA gyrase B. DNA primase C. DNA helicase D. DNA topoisomerase I E. DNA topoisomerase 1I

d

Which of the following might decrease the transcription of only one specific gene in a eukaryotic cell? a) a decrease in the amount of RNA polymerase II b) a decrease in the amount of RNA polymerase III c) mutations that place stop codons into transcribed DNA that precedes the gene's coding sequence d) mutations that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site e) a decrease in the amount of TFIID

d

Which of the following mutations would affect the protein sequence the most? a) A mutation in the first nucleotide of a codon to another nucleotide b) Deletion of 3 nucleotides early in the coding sequence c) A silent mutation in the wobble base pair d) An insertion of 2 nucleotides early in the coding sequence e) An insertion of 3 nucleotides early in the coding sequence

d

Which of the following nucleotides is hydrolyzed in both transcription and in translation elongation? A. dATP B. TTP C. UTP D. GTP E. CTP

d

Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble? a) GAU and GAA b) CUU and UUU c) AAU and AAC d) GUU and GUC e) AAA and AAC

d

Which of the following polymerases is primarily responsible for producing mRNAs in eukarotes: a) Poly A polymerase b) DNA polymerase I c) RNA polymerase I d) RNA polymerase II e) RNA polymerase

d

Which one of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon? a) Eukaryotes have three types of RNA polymerase. b) Eukaryotic RNA polymerases require general transcription factors. c) Potential prokaryotic signals sequences are removed by the spliceosome during RNA splicing. d) The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter. e) Prokaryotic genes are packaged into nucleosomes.

d

Which protein binds to regions within the whole exon and defines them for the splicing machinery? A. snRNPs. B. EJC proteins C. CBCs. D. SR proteins. E. hnRNPs.

d

Which structure is normally found on the 5' end of a DNA strand? a) hydroxyl group b) sulfur group c) nitrogenous base d) phosphate group e) carboxyl group

d

Each aminoacyl-tRNA synthetase activates a certain amino acid by attaching it to its corresponding tRNA(s) through a high-energy linkage... a) between the amino group of the amino acid and the 3' hydroxyl group of the tRNA. b) between the amino group of the amino acid and the 5' hydroxyl group of the tRNA. c) between the amino group of the amino acid and the 3' or 2' hydroxyl group of the tRNA. d) between the carboxyl group of the amino acid and the 5' hydroxyl group of the tRNA. e) between the carboxyl group of the amino acid and the 3' or 2' hydroxyl group of the tRNA.

e

In the following schematic drawing, two DNA molecules are shown before and after the action of a protein that is also involved in the process of DNA replication in eukaryotes. What is this protein called? (there is a pic) A. DNA ligase B. DNA gyrase C. DNA polymerase I D. DNA topoisomerase I E. DNA topoisomerase II

e

Reading frames and splicing. You have discovered a gene (below) that is alternatively spliced to produce several forms of mRNA in various cell types, three of which are shown in the figure below. The lines connecting the exons that are included in the mRNA indicate the splicing. From your experiments, you know that protein translation begins for all variants in exon 1. For all forms of the mRNA, the encoded protein sequence is the same in the regions of the mRNA that correspond to exons 1,4,5,6, 9, and 10 (indicated by arrows). Exons 2 and 3 are alternative exons used in different mRNA, as are exons 7 and 8. Which of the following statements about exons 2 and 3 must be true? (a) Exons 2 and 3 must have the same number of nucleotides. (b) Exons 2 and 3 must have different numbers of nucleotides. (c) Exons 2 and 3 must have the same numbers of nucleotides as 7 and 8 (d) Exons 2 and 3 must contain an integral number of codons (that is, the number of nucleotides divided by 3 must be a whole number). (e) Exons 2 and 3 must contain a number of nucleotides that when divided by 3, leaves the same remainder (that is, 0, 1, or 2).

e

Which is the enzyme that always keeps DNA negatively supercoiled in bacteria a) DNA helicase b) DNA topoisomerase I c) DNA topoisomerase 1I d) DNA primase e) DNA gyrase

e

Which of the following are the primary target(s) for antibiotic drugs that target bacteria? a) prokaryotic transcription machinery only b) prokaryotic translation machinery only c) synthesis of peptidoglycan chains in bacterial cell walls only d) both synthesis of peptidoglycan chains in bacterial cell walls and prokaryotic transcription machinery e) both synthesis of peptidoglycan chains in bacterial cell walls and prokaryotic translation machinery

e

Which of the following general transcription factors phosphorylates the polymerase to release it from the other general transcription factors and begin transcription: a) TFIIB b) TFIID c) TFIIE d) TFIIF e) TFIIH

e

52) Which of the following general transcription factors unwinds DNA at the transcription start point: a) DNA helicase b) TFIIB c) TFIID d) TFIIH e) TFIIE f) TFIIF

D

The enzyme that removes the RNA primers from newly synthesized DNA and replaces them with DNA nucleotides is: a. DNA polymerase I b. DNA polymerase III c. DNA primase d. DNA ligase e. Topoisomerase (DNA gyrase)

a

The enzyme that synthesizes the new DNA strand during replication is: a. DNA polymerase I b. DNA polymerase III c. DNA primase d. DNA ligase e. Topoisomerase (DNA gyrase)

b

The ribosome is important for catalyzing the formation of peptide bonds. Which of the following statements is true? (a) The number of rRNA molecules that make up a ribosome greatly exceeds the number of protein molecules found in the ribosome. (b) The catalytic site for peptide bond formation is formed primarily from an rRNA. (c) Once the large and small subunits of the ribosome assemble, they will not separate from each other until degraded by the proteasome. (d) The tRNA molecule does not play any role in the active site- it only brings an amino acid to the ribosome. (e) The large subunit of the ribosome is important for initial binding to the mRNA.

b

The type of protein that DNA is wrapped around is called? a) Centrosomes b) Histones c) Keytones d) Protophones e) Kinetochores

b

What is the main source of the free energy for the mechanical work performed by DNA helicases during DNA replication in our cells? A. The hydrogen-bonding energy in the DNA double helix B. ATP hydrolysis by the helicase C. Thermal energy in the nucleus D. The energy of SSB binding to single-stranded DNA E. ATP hydrolysis by DNA topoisomerases

b

Which of the following chaperone acts as an isolation chamber for protein folding? A. HSP40. B. HSP60. C. HSP70. D. HSP90. E. HSP27.

b

Which of the following helps maintain the contact between the polymerase and DNA during RNA synthesis: a) clamp loader protein b) PCNA c) DNA primase d) single strand DNA binding protein e) none of the above

b

Which protein(s) is not involved in the generation and recognition of the mRNA 3' poly A tail? A. RNA polymerase II. B. EJC proteins. C. Poly A polymerase. D. CstF E. CPSF.

b

Which proteins are involved in nonsense-mediated degradation? A. U2 auxillary factor2. B. Upf proteins C. Poly A binding proteins D. snoRNPs. E branch point binding protein.

b

48) Which of the following statements is true about mRNA in prokaryotes: a) The 5' end has a 7-methylguanylate cap. b) The 3' end has a poly-A tail. c) its synthesis requires the sigma factor. d) introns must be removed before translation. e) mRNAs can only encode one protein.

c

In what way is Transcription is similar to DNA Replication? a) the same nucleotides are used for polymerization. b) an RNA transcript is synthesized discontinuously and the pieces are then joined together. c) nucleotide polymerization occurs only in the 5′-to-3′ direction. d) the newly synthesized RNA remains paired to the template DNA. e) it uses the same enzyme as that used to synthesize RNA primers during DNA replication.

c

47) The mechanism of DNA replication gives rise to the "end-replication problem" for linear chromosomes. Over time, this problem leads to loss of DNA from the ends of chromosomes. Loss of nucleotides during replication is balanced by addition of nucleotides by telomerase. In humans, however, telomerase is turned off in most somatic cells early in development, so that chromosomes become shorter with increasing rounds of replication. Consider one round of replication in a human somatic cell. Which one of the following statements correctly describes the status of the two daughter chromosomes relative to the parent chromosome? a) One daughter chromosome will be shorter at both ends; the other daughter chromosome will be normal at both ends. b) One daughter chromosome will be shorter at one end; the other daughter chromosome will be normal at both ends. c) One daughter chromosome will be shorter at both ends; the other daughter chromosome will be will be shorter at only one end. d) Both daughter chromosomes will be shorter at one end, which is the opposite end in the two chromosomes. e) Both daughter chromosomes will be shorter at one end, which is the same end in the two chromosomes. f) Both daughter chromosomes will be shorter at both ends.

d

Activation of an amino acid by an aminoacyl-tRNA synthetase involves the covalent linkage of... a) phosphate to the amino acid. b) AMP to the tRNA. c) ADP to the tRNA. d) AMP to the amino acid. e) ADP to the amino acid.

d

Compared to the human genome, the genome of yeast typically has ... a) more repetitive DNA. b) longer genes. c) longer chromosomes. d) a higher percentage of coding DNA. e) more introns.

d