43.Which of the following is NOT a characteristic of a riboswitch? (A) They are structures that exist in the 5' untranslated region of some mRNA molecules. (B) They exert gene expression control only at the level of translation. (C) They physically bind to small-molecule metabolites. (D) Ligand-binding to the riboswitch can sequester the Shine-Delgarno sequence.

3. Consider an experiment in which nucleic acids are separated using agarose gel electrophoresis. In the gel you load the following samples: Lane 1: a population of linearized 3000-bp double-stranded DNA (dsDNA) molecules. Lane 2: a population of circular 3000-bp double-stranded DNA (dsDNA) molecules Which population of nucleic acids would most likely migrate through the gel fastest, and in which direction through the gel will these molecules migrate? (A) The linearized dsDNA would most likely migrate faster than the circular dsDNA. AlI DNA molecules would migrate toward the positive end of the gel. (B) The linearized dsDNA would most likely migrate faster than the circular dsDNA. AIl DNA molecules would migrate towards the negative end of the gel. (C) The circular dsDNA would most likely migrate faster than the linearized dsDNA. All DNA molecules would migrate toward the positive end of the gel. (D) The circular dsDNA would most likely migrate faster than the linearized dsDNA. All DNA molecules would migrate toward the negative end of the gel

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