Final answer:
The repeating sugar and phosphate units in a single DNA strand make up the sugar-phosphate backbone, which serves as the DNA strand's structural framework and supports the genetic material within.
Step-by-step explanation:
The repeating sugar and phosphate units in a single DNA strand make up what is known as the sugar-phosphate backbone. This structure is fundamental to the molecular architecture of DNA. The sugar involved is deoxyribose, a five-carbon sugar, which is part of each nucleotide that constructs DNA. These nucleotides, which are the monomer units of DNA, consist of the deoxyribose sugar, a phosphate group, and a nitrogenous base.
The phosphate group of one nucleotide covalently bonds to the 5' carbon of the sugar of another nucleotide, and this alternating pattern of sugar and phosphate creates a robust framework for the DNA strand. In the double-helix structure of DNA, the sugar-phosphate backbone is on the outside with the nitrogenous bases on the inside, held together by hydrogen bonds. This formation allows DNA to carry genetic information critical for organismal development and function.