1. Sugar-phosphate backbone: This forms the structural framework of the DNA molecule. It consists of alternating sugar (deoxyribose) and phosphate groups linked together.
2. Nitrogenous bases: These are the "rungs" of the DNA ladder. There are four types: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
3. Hydrogen bonds: These hold the two strands of the helix together. Adenine always pairs with Thymine (A-T) through two hydrogen bonds, while Guanine always pairs with Cytosine (G-C) through three hydrogen bonds.
4. Base pairing: This refers to the specific pairing of the nitrogenous bases: A with T and G with C. This pairing is crucial for DNA replication and transcription.
Therefore, the four components of a double helix, as it pertains to DNA, are the sugar-phosphate backbone, nitrogenous bases, hydrogen bonds, and base pairing.
