You want to use a plasmid to transform an e. coli cell with a cry toxin gene from bacillus thuringiensis in order to express the toxin in e. coli. in addition to the gene of interest, what other elements must be included on the plasmid? select all that apply. a gene encoding an e. coli-specific dna polymerase. an origin of replication. a selectable marker (e. g., a gene encoding antibiotic resistance). a promoter allowing the expression of the cry gene in an e. coli host.