Question 1 In the presence of lactose, the lac repressor is: Not synthesized. Ac

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Question 1 In the presence of lactose, the lac repressor is: Not synthesized. Actively synthesized and binds to the lac operator to inhibit transcription. Actively synthesized but inhibited by lactose. Actively synthesized and activated by lactose. 0.5 points Question 2 If you treated cultured chicken fibroblast cells with a peptide that inhibits 5’ mRNA capping, what would you likely see? Slowed transcription of all RNAs. Lower levels of mRNAs in the cytoplasm. Decreased production of proteins. Decreased stability of rRNAs. Both 2nd and 3rd answers above All of the above 0.5 points Question 3 Shown below is a drawing showing the result of an experiment in which an RNA molecule is allowed to mix with genomic DNA that has been denatured by boiling, and the two molecules are allowed to hybridize. The DNA strand is presumed to be the lighter-shaded one on the top. Note that only one strand of DNA is shown. What type of RNA is this most likely to be? An eukaryotic mRNA An eukaryotic rRNA An eukaryotic tRNA A bacterial mRNA A bacterial rRNA A bacterial tRNA any eukaryotic RNA 0.5 points Question 4 A 3-base deletion in the AAUAAA sequence in the 3' untranslated region of an mRNA that eliminates the AAU, thereby preventing RNA Polymerase from polyadenylating the mRNA would have the effect of: decreasing the number copies of the polypeptide that would be translated from this mRNA decreasing the length of the encoded protein by one amino acid. This may or may not affect the protein’s function because it is not a frameshift mutation drastically altering the polypeptide sequence because it is a frameshift mutation. 0.5 points Question 5 Shown below is a diagram of a eukaryotic replication bubble with only the template shown. Where would the enzyme topoisomerase be? (Examine the template DNA very carefully before answering this question!) A B C D 0.5 points Question 6 George Beadle and Edward Tatum performed an experiment in which they made single-gene mutations in the bread mold Neurospora crassa. Which of the following states their primary finding? Multiple protein-coding genes may be found on a single transcript. Different mutations impair different genes encoding different enzymes in the pathway for synthesis of Arginine. Neurospora auxotrophs require Arginine supplementation in order to grow. Arginine is an essential amino acid for Neurospora. All of the above 0.5 points Question 7 In what way is RNA transcription similar to DNA replication? It uses the same 4 nucleotide bases. It requires a primer. The newly-formed polymer is the reverse complement of the template. Polymerization happens only at the 5’ end. All of the above are the same for replication and transcription. 0.5 points Question 8 Which of the following aspects of transcription is unique to bacteria? Transcription and translation may occur simultaneously. Only bacteria have mRNAs RNA splicing. A 7-methyl guanosine cap at the 5' end of mRNA increases stability. All of the above 0.5 points Question 9 Which of the following characteristics of transcription is true in bacteria, but NOT in Eukaryotes? Transcription and translation can occur simultaneously. Transcription of multiple RNAs from the same gene may occur simultaneously. Transcription is required to make rRNAs, tRNAs, and mRNAs. RNA Polymerase is activated by a transcription factor that binds to the core promoter. 0.5 points Question 10 Which of the following statements describing transcription is FALSE? Transcription of multiple RNAs from the same gene may occur simultaneously. rRNAs, tRNAs, and mRNAs are all made through transcription. Transcription in Eukaryotes requires a significant amount of unwinding of the chromatin. RNA Polymerase is activated when TFIID binds to the origin of replication in Eukaryote

Explanation / Answer

Answer for question number 1 : The correct answer is C (Actively synthesized but inhibited by lactose).

Explanation : In absence of lactose, repressor binds to operator and prevents the binding of RNA polymerase to the promoter site due to steric hinderance and prevents the transcription of lac operon structural genes. whereas, in the presence of lactose, binding of repressor to the operator site is inhibited allowing the structural genes to undergo transcription.

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