[Campbell Biology P.471] Based on Figure 20.8 and its accompanying description, which of the... | Practice Question

Based on Figure 20.8 and its accompanying description, which of the following sequences best describes the process of creating a recombinant DNA plasmid and selecting transformed host cells?

  • A: DNA fragments (gene of interest) are obtained; cloning vector is cut with restriction enzyme; fragments and vector are ligated; recombinant plasmids are added to host cells; cells are treated with antibiotic.
  • B: Cloning vector is cut; host cells are treated with antibiotic; DNA fragments are obtained; ligation occurs; recombinant plasmids are added to cells.
  • C: Recombinant plasmids are formed by ligation; DNA fragments are obtained using PCR; cloning vector is prepared; host cells are selected.
  • D: Cloning vector is ligated with DNA fragments; host cells are mixed with recombinant DNA; PCR primers are designed; cells are grown on antibiotic media.

Explanation

Figure 20.8 illustrates the process: first, PCR primers are used to obtain DNA fragments with restriction sites. Simultaneously, the cloning vector is cut with the same restriction enzyme. Then, the fragments and the vector are mixed and ligated to form recombinant DNA plasmids. These plasmids are added to bacterial host cells, and finally, the cells are treated with an antibiotic. Only cells that have taken up the plasmid containing an antibiotic resistance gene will survive, providing a selection mechanism.