The cohesive end of the lambda genome is known as the A. att B. cos C. xis D. ori E. int Which of the following words or phrases is not associated with conjugation? a. “Rolling circle replication” b. F (fertility) plasmid c. Hfr strains d. “Minute” designations on a chromosome e. Electroporation Assume that the manA gene, required for metabolism of the sugar mannitol, is regulated by a mechanism involving an inducer:activator complex where mannitol is the inducer. Which of the following statements is true? a. Binding of mannitol to the activator turns on transcription of manA as the complex stimulates RNA polymerase to bind near the start of the gene. b. Binding of mannitol to the activator turns off transcription of manA as the complex stimulates RNA polymerase to bind near the start of the gene. c. Binding of mannitol to the activator turns on transcription of manA as the complex causes RNA polymerase to dissociate from near the start of the gene. d. Binding of mannitol to the activator turns off transcription of manA as the complex causes RNA polymerase to dissociate from near the start of the gene. e. Mannitol induces diauxic growth when used as the sole carbon source. GroE and GroL work together as a “chaperonin” to: b. Properly fold RNA molecules into their final three-dimensional shape. c. Promote coupled transcription-translation by stabilizing polysomes. d. Target proteins to their correct location (e.g., cytoplasm, periplasm, extracellular space). e. Assist in protein folding. f. Stabilize interactions between the primase, DNA polymerase I, DNA polymerase III, and ligase that are needed for synthesis of the lagging strand. Which of the following would not be a favorable trait for a prokaryotic expression vector? A. Low copy number of the desired gene B. Strong transcriptional promotors C. Presence of a bacterial ribosome binding site D. Proper reading frame and codon usage E. Easy detection of inserts Secondary metabolite refers to A. a 19th century religious sect B. products formed as a consequence of the inactivation of antibiotics C. products formed during the respiration of primary metabolites D. substrates consumed after primary ones have been consumed E. metabolites produced during stationary phase In the biosynthesis of penicillins, the type of penicillin produced can be controlled by A. The addition of specific precursors to the growing culture and chemical modification after isolation B. Changing the growth stage and limiting the concentration of the primary carbon source C. Removing all glucose from the growth medium so that there can be no catabolite repression D. Maintaining the culture at mid exponential phase and inducing atypical production with the addition of exogenous antibioticsE. Growing the culture in a biphasic system so that excreted penicillin will be concentrated in the organic phase thus removing it from the aqueous phase Which of the following is not considered a cloning vector? A. bacteriophage B. viroids C. vaccinia virus D. cosmids E. plasmids The antibiotic resistance determinants included in many cloning vectors permit the ____ of cells bearing the vector. A. direct enrichment B. spontaneous lysis C. reverse transcription D. development of competence E. aggregation Assume that the pyrD gene, required for pyrimidine biosynthesis, is regulated by a mechanism involving a corepressor:repressor complex where pyrimidines act as the corepressor. Which of the following statements is true? a. Binding of pyrimidine to the repressor turns on transcription of pyrD as the complex binds to the DNA near the start of the gene. b. Binding of pyrimidine to the repressor turns off transcription of pyrD as the complex binds to the DNA near the start of the gene. c. Binding of pyrimidine to the repressor turns on transcription of pyrD as the complex dissociates from the DNA near the start of the gene. d. Binding of pyrimidine to the repressor turns off transcription of pyrD as the complex dissociates from the DNA near the start of the gene. e. Transcription depends on whether light is present or not due to the photochemical crosslinking of thymine (a type of pyrimidine). Several methodologies have been used for the production of vinegar. In the trickle method, ____ are used to provide a ______ for acetic acid bacteria to grow on. A. Small pebbles :: surface B. Wood chips :: carbon source C. Wood chips :: surface D. Polystyrene beads :: filtration system E. Wood chips :: filtration system DNA microarrays (or DNA chips) can be used to monitor the cellular concentrations of a large number of specific RNA molecules simultaneously. This technique was used to compare RNA samples from culture #1 grown in minimal medium and in culture #2 grown in a rich medium (e.g., yeast extract). A reasonable outcome from such an experiment is: a. The tRNA concentrations are specifically increased in culture #1 over those in culture #2. b. The ribosomal RNA concentrations are specifically increased in culture #1 over those in culture #2. c. The total mRNA concentrations are elevated in culture #1. d. Dozens (or possibly hundreds) of specific RNAs are increased in concentration in culture #1 over culture #2, while a different set of dozens (or 100s) of specific RNAs are decreased in #1 versus #2. e. A defined set of specific RNAs will be found at lower concentrations in culture #2 versus culture #1, and no RNA in culture #2 will exceed the concentration of that RNA in culture #1. The “promoter sequence”: a. Is also known as the origin of replication. b. Is recognized by RNA polymerase (plus sigma) as the site adjacent to transcription initiation. c. Binds to the 30S subunit of the ribosome (along with other components) as part of translation initiation. d. Is needed for synthesizing the RNA primer required for lagging strand synthesis. e. Is specifically methylated to prevent digestion by endonucleases.The sequence of events in a phage infection is determined by the expression of the phage genome. In the case of T7 and T4, two relatively large ds DNA bacteriophage, the infection process is divided into early, middle, and late expression. Early and middle expression usually include genes coding for ____&_____ while genes expressed late in infection include those coding for ____&____. A. cell lysis & immunity :: capsomeres and rRNAs B. replication & transcription :: head & tail proteins
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