what are the two parts that make up the backbone of dna
The sugar and phosphate group make up the backbone of the DNA double helix, while the bases are located in the middle. A chemical bond between the phosphate group of one nucleotide and the sugar of a neighboring nucleotide holds the backbone together. Chemical bonds (hydrogen bonds) between the bases that are across from one another hold the two strands of the double helix together. Bases. There are four types of bases in DNA. They are called: * Adenine (A) * Cytosine (C)