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
A DNA molecule is a long, double-stranded helix structure that contains the genetic information of an organism. It consists of two nucleotide strands wrapped around each other in a spiral shape.
A nucleotide is the basic unit or building block of DNA. It consists of three components: a sugar molecule (deoxyribose), a phosphate group, and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine).
Base pairing refers to the specific interaction between complementary nitrogenous bases in DNA. Adenine always pairs with thymine (A-T), while guanine always pairs with cytosine (G-C).
Hydrogen bonds: Hydrogen bonds are relatively weak chemical bonds between hydrogen atoms and electronegative atoms (like oxygen or nitrogen).