Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
In biology, antiparallel orientation refers to the opposite arrangement of the sugar-phosphate backbones in a DNA double helix. One strand runs from 5' to 3' direction, and the other runs from 3' to 5'.
This is when specific nitrogenous bases in DNA or RNA molecules pair up due to hydrogen bonding. Adenine pairs with thymine (in DNA) or uracil (in RNA), and cytosine pairs with guanine.
This term describes the structure of DNA, which looks like a twisted ladder or spiral staircase. It consists of two strands that twist around each other.
Hydrogen Bonding: A type of chemical bond that occurs when a hydrogen atom bonded to an electronegative atom forms an electrostatic connection with another electronegative atom nearby.