Molecular and Cell Biology Quiz

BMB/MICRB251, Dr. Lindner; Exam 2 - Oct 1, 2018 Started: Sep 30 at 9:41am  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  Quiz Instructions There are 40 multiple choice questions. You have 60 minutes to complete the exam. Choose the best response to each question. Question 1 2 pts DNA replication occurs by a semi-conservative mechanism where DNA polymerase… Reads a DNA template in the 5’ to 3’ direction and produces a new DNA strand in the 3’ to 5’ direction. Reads a DNA template in the 3’ to 5’ direction and produces a new DNA strand in the 5’ to 3’ direction. Reads a DNA template in the 5’ to 3’ direction for leading strand synthesis, but reads the DNA template in the 3’ to 5’ direction for lagging strand synthesis. Reads a DNA template in the 3’ to 5’ direction for leading strand synthesis, but reads the DNA template in the 5’ to 3’ direction for lagging strand synthesis. Question 2 2 pts Two key differences between DNA polymerase and RNA polymerase include: RNA polymerase requires a 3’ hydroxyl to add new nucleotides onto a growing chain but is less accurate, while DNA polymerase can add new nucleotides without a primer and is more accurate. DNA polymerase requires a 3’ hydroxyl to add new nucleotides onto a growing chain and is very accurate, while RNA polymerase can add new nucleotides without a primer but is less accurate. RNA polymerase requires a 3’ hydroxyl to add new nucleotides onto a growing chain and is very accurate, while DNA polymerase can add new nucleotides without a primer but is less accurate. DNA polymerase requires a 3’ hydroxyl to add new nucleotides onto a growing chain but is less accurate, while RNA polymerase can add new nucleotides without a primer and is more accurate. Question 3 2 pts The exonucleolytic site of DNA polymerase… Incorporates new nucleotides into the growing DNA strand. Is another name for the polymerization site. Removes mismatched nucleotides. Processes double-strand DNA breaks. Question 4 Okazaki fragments are… The RNA sequences found on the leading strand of DNA synthesis. The RNA sequences found on the lagging strand of DNA synthesis. The long DNA sequences produced on the lagging strand after DNA ligase seals their nicks. The short DNA sequences produced on the lagging strand before DNA ligase seals their nicks. 2 pts Question 5  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts DNA primase produces… Short DNA fragments that anneal to the newly synthesized DNA. A polymer of RNA. The DNA replication bubble. The 2’ hydroxyl group used to initiate DNA synthesis on a new strand. Question 6 2 pts What enzyme removes the product of DNA primase? RNase H A DNA exonuclease DNA ligase DNA primase does not produce anything, there is nothing to remove. Question 7 2 pts True or False: DNA ligase uses ATP to seal nicks in the phosphodiester backbone? True False Question 8 2 pts How many DNA polymerases are found in an active replication fork? 0 1 2 4 Question 9 What is the function of the sliding clamp, called PCNA? It improves the clamping motion that DNA polymerase uses to add new nucleotides into the growing DNA strand. It keeps DNA polymerase associated with the replication fork. It promotes the dissociation of DNA polymerase from the leading strand. It consumes ATP to load a ring around the double-stranded DNA. 2 pts Question 10  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts After separating double-stranded DNA into single-stranded DNA in the DNA replicative bubble… DNA helicases bind to the DNA backbone to keep it accessible. DNA primases melt any complementary base pairing that forms there. SSB proteins prevent duplex DNA structures from forming. DNA ligases incorporate new nucleotides using the template strand. Question 11 2 pts DNA helicases produce torsional stress in the DNA that can be relieved by… DNA ligase DNA primase Topoisomerase Sliding clamp loader Question 12 2 pts A key difference between topoisomerase 1 and topoisomerase 2 is that… Topoisomerase 1 consumes ATP, while topoisomerase 2 does not. Topoisomerase 2 consumes ATP, while topoisomerase 1 does not. Topoisomerase 1 is used for DNA replication, and topoisomerase 2 is used for transcription of RNA. Topoisomerase 1 is only found in prokaryotes, Topoisomerase 2 is only found in eukaryotes. Question 13 2 pts What amino acid is critical for topoisomerase 1 to form a temporary covalent bond with DNA? Cys Phe Tyr Met Question 14 Prokaryotes use Initiator proteins to… Initiate transcription Initiate DNA repair Initiate DNA replication Initiate transcriptional termination 2 pts Question 15  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts In eukaryotes, “licensing” of DNA replication refers to… Allowing an origin to fire once and only once per cell cycle. Preventing the rebroadcast, retransmission, or account of DNA replication, without the express written consent of DNA polymerase. Marking a sequence of DNA as an origin of replication. The process that ensures the cell completes DNA replication during S phase. Question 16 2 pts What first marks a segment of DNA as an origin of DNA replication in eukaryotes? DNA primase DNA ligase ORC Initiator Question 17 2 pts What is a histone chaperone? One of the eight proteins that are used to wrap DNA into a nucleosome. The regulatory protein the changes the level of compaction of the nucleosome. A protein that binds to components of the nucleosome while DNA polymerase replicates associated DNA. A sliding clamp protein. Question 18 2 pts The chromosome end problem is solved by… Extension of the lagging strand by telomerase. Extension of the leading strand by DNA polymerase. Ligation of RNA adaptors to the very end of chromosomes. Converting nucleotides containing ribose into nucleotides containing deoxyribose. Question 19 X-rays can cause double-strand DNA breaks (DSB’s). What repair pathway is most commonly used to repair this kind of damage? Strand-Directed Mismatch Repair Base Excision Repair Nucleotide Excision Repair Non-Homologous End Joining 2 pts Question 20  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts UV light can cause the formation of pyrimidine dimers. What repair pathway is most commonly used to repair this kind of damage? Strand-Directed Mismatch Repair Base Excision Repair Nucleotide Excision Repair Non-Homologous End Joining Question 21 2 pts Deamination of cytosine into uracil happens frequently in eukaryotes. What repair pathway is most commonly used to repair this kind of damage? Strand-Directed Mismatch Repair Base Excision Repair Nucleotide Excision Repair Non-Homologous End Joining Question 22 2 pts The order of events that occurs during homologous recombination include… A. DNA ligase seals the nick in the phosphodiester backbone B. The 5’ ends are resected on both strands C. DNA polymerase extends the strand D. A Double-Strand Break occurs in DNA E. The 3’ overhang is coated in RecA and invades a homologous chromosome Place the events in order from first to last. D, E, B, C, A D, B, E, C, A D, C, E, A, B D, E, C, B, A Question 23 2 pts DNA transposons are different from retrotransposons in that… DNA transposons can move from one cell to another, retrotransposons cannot. DNA transposons use an integrase protein to insert into the genome, retrotransposons use reverse transcriptase to insert into the genome. DNA transposons move as DNA, retrotransposons produce an RNA intermediate that is reverse transcribed into DNA. DNA transposons do not encode proteins, retrotransposons do. Question 24 What is released when a new deoxynucleotide is added to the growing DNA strand? ATP Pyrophosphate Deoxyribose DNA polymerase 2 pts Question 25  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts What regulatory events occur to prevent ORC from activating an origin of DNA replication repeatedly? ORC proteins can only bind to DNA in G1. ORC proteins are phosphorylated and dephosphorylated. ORC proteins must be recruited by the MCM helicase. ORC proteins are rapidly degraded after allowing the origin to fire. Question 26 2 pts True or False: RNA polymerase reads a DNA template 5’ to 3’ and produces an RNA 3’ to 5’. True False Question 27 2 pts The transcriptional bubble in prokaryotes is produced by… TFIID TFIIH Sigma factor and RNA polymerase TATA-Binding Protein Question 28 2 pts In this segment of double-stranded DNA, the -35 element is marked in red and the -10 element is marked in blue. What is the sequence of the RNA that will be transcribed? AAAAAAAAAAAAAAAAAA TTTTTTTTTTTTTTTTTT UUUUUUUUUUUUUUUUUU GGGGGGGGGGGGGGGGGG CCCCCCCCCCCCCCCCCC Question 29 In this segment of double-stranded DNA, the -35 element is marked in blue and the -10 element is marked in red. What is the sequence of the template that will be transcribed? AAAAAAAAAAAAAAAAAA TTTTTTTTTTTTTTTTTT UUUUUUUUUUUUUUUUUU GGGGGGGGGGGGGGGGGG CCCCCCCCCCCCCCCCCC 2 pts Question 30  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts Which polymerase transcribes the coding sequences of mRNAs in eukaryotes? Poly(A) Polymerase RNA Polymerase 1 RNA Polymerase 2 RNA Polymerase 3 Question 31 2 pts In eukaryotes, a drug that inhibits RNA polymerase 3 will first affect the transcription of… rRNA mRNA tRNA Poly(A) tail Question 32 2 pts What role does TFIID play in transcription? TFIID binds to the terminator sequence to stop transcription. TFIID acts as a regulatory kinase and helicase. TFIID prevents RNA polymerase II from associating with non-promoter sequences. TFIID binds to the INR and DPE sequences to distort the promoter sequences. Question 33 2 pts A monocistronic mRNA is defined by… The presence of a 5’ triphosphate The absence of introns The presence of one coding sequence The absence of a poly(A) tail Question 34 Eukaryotic mRNAs are protected on the 5’ end by… A methylated guanosine A polymer of adenine A triphosphate snRNPs 2 pts Question 35  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz.  2 pts Eukaryotic mRNAs are typically processed in this order: Introns spliced out, poly(A) tail added, capped Poly(A) tail added, capped, introns spliced out Capped, poly(A) tail added, introns spliced out Capped, introns spliced out, poly(A) tail added Question 36 2 pts What will occur if a mutation in the 3’ splice site of intron 1 were present? Intron 1 would not be spliced out. Intron 1 would be spliced out and Exon 1 and Exon 2 would be joined together. Intron 1-Exon2-Intron2 would be spliced out, and Exons 1 and Exon 3 would be joined together. Exon 2 would be spliced out, and Intron 1 and Intron 2 would be joined together. Question 37 2 pts What will occur if a mutation in the 5’ splice site of intron 1 were present? Intron 1 would not be spliced out. Intron 1 would be spliced out and Exon 1 and Exon 2 would be joined together. Intron 1-Exon2-Intron2 would be spliced out, and Exons 1 and Exon 3 would be joined together. Exon 2 would be spliced out, and Intron 1 and Intron 2 would be joined together. Question 38 The first transesterification reaction of splicing requires… The 2’ hydroxyl on the 5’ splice site The 2’ hydroxyl on the 3’ splice site The 2’ hydroxyl on the branch point A All of these are required. 2 pts Question 39  You started this quiz near when it was due, so you won't have the full amount of time to take the quiz. 2 pts  The addition of a poly(A) tail requires... snRNPs to hybridize to the mRNA Transcription of a cleavage signal A polymer of T’s in the DNA template The TATA box Question 40 2 pts What eukaryotic process uses homologous recombination with crossover events to generate genetic diversity? Strand-Directed Mismatch Repair Mitosis Meiosis Apoptosis Not saved Submit Quiz