DNA, or deoxyribonucleic acid, is the fundamental building block of life. It's a molecule composed of simpler units called nucleotides.
The Nucleotide: DNA's Basic Unit
Each nucleotide consists of three parts:
- A phosphate group: A phosphorus atom bonded to four oxygen atoms.
- A sugar group: Specifically, deoxyribose, a five-carbon sugar.
- A nitrogenous base: One of four molecules: adenine (A), thymine (T), guanine (G), and cytosine (C). These bases pair up in a specific way: A always pairs with T, and G always pairs with C. These pairings are held together by weak hydrogen bonds.
The Double Helix Structure
These nucleotides are linked together to form two long strands that twist around each other to create the famous double helix structure. The phosphate and sugar groups form the "backbone" of each strand, while the nitrogenous bases face inwards, forming the base pairs that hold the two strands together. (Source: genome.gov, cancer.gov, igenomix.net, medlineplus.gov, my.clevelandclinic.org, en.wikipedia.org, jax.org, genomicseducation.hee.nhs.uk)
This double-stranded helix, held together by the hydrogen bonds between the base pairs, is crucial for DNA's function in storing and transmitting genetic information.
