Answer: transposons

AnswerCrossword Clue
TRANSPOSONSDNA elements also called jumping genes
transposonsA chromosomal segment that can undergo transposition, esp. a segment of bacterial DNA that can be translocated as a whole between chromosomal, phage, and plasmid DNA in the absence of a complementary sequence in the host DNA
transposonsTRANSPOSON, a sequence of DNA capable of moving to different sites in a chromosome