Final answer:
Triplex DNA is a type of DNA structure in which three DNA strands form a helical structure. It is different from the usual double helix structure of DNA.
Step-by-step explanation:
Triplex DNA refers to a type of DNA structure in which three DNA strands form a helical structure. This is different from the usual double helix structure of DNA, which consists of two DNA strands. In triplex DNA, one of the strands binds to a double-stranded DNA molecule through hydrogen bonding.