Final answer:
DNA consists of nucleotides made up of a nitrogenous base, deoxyribose sugar, and phosphate group. These nucleotides form a double helix structure with the sugar-phosphate backbone and paired bases held together by hydrogen bonds.
Step-by-step explanation:
Components of a DNA Molecule
The building blocks of DNA are known as nucleotides. Each nucleotide within the DNA molecule is comprised of three components: a nitrogenous base, a deoxyribose (5-carbon sugar), and a phosphate group. The nucleotide structure is the foundation for the double helix of DNA, where these nucleotides connect to form long chains through the sugar and phosphate groups, creating a sugar-phosphate backbone.
There are four types of nitrogenous bases in DNA: the purines - adenine (A) and guanine (G), and the pyrimidines - cytosine (C) and thymine (T). These bases pair specifically (A with T and G with C) across the double helix, held together by hydrogen bonds. Such base pairing is crucial for the replication and transcription processes that DNA undergoes during cell division.
To summarize, a DNA molecule is fully constructed when the nucleotides link together, with their phosphate group of one nucleotide connecting to the sugar group of another, thereby forming the sugar-phosphate backbone while the nitrogenous bases extend from this backbone, inside the double helix structure.