Definition of "double helix" []

• The coiled structure of double-stranded DNA in which strands linked by hydrogen bonds form a spiral configuration, with the two strands oriented in opposite directions. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Not only can single units called nucleotides of DNA accidentally change when the DNA is copied in a new generation, but whole chunks of the double helix can accidentally either be duplicated or be left out."
• "The molecular chain known as actin forms in pairs that twist into a double helix as does DNA."
• "If you gradually heat DNA, there comes a point – somewhere around 85°C – when the bonding between the two strands of the double helix breaks, and the two helices separate."