Nematic liquid crystals (LC) were exposed to isolated DNA molecules extended on a surface that imparted a negligible influence on the LC orientation. Although single-stranded DNA aligned the LC in the extension direction, double-stranded DNA (dsDNA) caused alignment at an oblique angle, providing a characteristic response to the chiral dsDNA helix that was readily observed optically. The intrinsic amplification due to LC orientational correlations enabled a macroscopic visible response to a single molecule of extended dsDNA.