Which of the Following is NOT a Useful Feature of a Plasmid

Question

Which of the following is NOT a useful feature of a plasmid for cloning?
A)expressed sequence tag
B)a cloning site
C)a replicator (origin of replication)
D)a selectable marker

Accepted Answer

Expressed sequence tags (ESTs) are short pieces of cDNA (complementary DNA) that are used for gene discovery and expression analysis, but they are not specifically useful for cloning a gene of interest into a plasmid. The other three features listed are essential for cloning, including a cloning site for insertion of the gene of interest, a replicator for replication of the plasmid in bacterial cells, and a selectable marker for identifying cells that have taken up the plasmid.