ABSTRACT
See also ECOLOGY HAC See HUMAN ARTIFICIAL CHROMO-
SOMES (HAC) HACCP See HAZARD ANALYSIS AND
CRITICAL CONTROL POINTS (HACCP) Hairpin Loop A section of highly curving,
single-stranded DNA or RNA formed when a long piece (string) of the DNA or RNA bends back on itself and hydrogen-bonds (is able to base pair) in some regions to form doublestranded regions. The structure can be visualized by taking a human hair, bending it back on itself and holding it in such a way as to halve its original length. The section where the two ends of hair lie next to each other represents the section of double-stranded DNA or RNA. At one end the hair will have to make a sharp turn and will form a loop. This loop represents the single-stranded hairpin loop.
