Denoting molecules that are parallel but have opposite directional polarity; e.g., the two strands of a DNA double helix.
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an·ti·par·al·lel .ant-i-'par-ə-.lel, .an-.tī-, -ləl adj parallel but oppositely directed or oriented <two \antiparallel chains of nucleotides comprise DNA>
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an·ti·par·al·lel (an″te-) (an″ti-parґə-lel) denoting molecules that are arranged side by side, but in opposite directions. For example, the strands of deoxyribonucleic acid are antiparallel, with their 5′ to 3′ linkages running in opposite directions.Medical dictionary. 2011.