QUESTION
The restriction endonuclease PstI cleaves the plasmid cloning vector pBR322pBR322. A researcher ligates an isolated DNA fragment from a eukaryotic genome (also produced by PstI cleavage) to the prepared vector. She then uses the mixture of ligated DNAs to transform bacteria and selects plasmid‑containing bacteria by growth in the presence of tetracycline.
The restriction endonuclease $P_{\text {stI }}$ cleaves the plasmid cloning vector $p B R 322$. A researcher ligates an isolated DNA fragment from a eukaryotic genome (also produced by $P$ stI cleavage) to the prepared vector. She then uses the mixture of ligated DNAs to transform bacteria and selects plasmid-containing bacteria by growth in the presence of tetracycline. In addition to the desired recombinant plasmid, what other types of plasmids might be found among the transformed bacteria that are tetracycline resistant? two or more isolated DNA fragments without the pBR.322 cloning vector the pBR322 cloning vector without the isolated DNA fragment two or more pBR322 cloning vectors ligated together the isolated DNA fragment without the pBR322 cloning vector The cloned DNA fragment is 1000 bp long and has an EcoRI site $250 \mathrm{bp}$ from one end. The researcher cleaves three different recombinant plasmids with EcoRI and analyzes them by gel electrophoresis, with the results shown in the image. Note that in pBR322, the Pstl and EcoRl restriction sites are about 750 bp apart. The entire plasmid with no cloned insert is $4361 \mathrm{bp}$. Size markers in lane 4 have the number of nucleotides noted. Which pattern indicates that two DNA fragments have been ligated into the cloning vector? lane 1 lane 2 lane 3
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