The DNA double helix is composed of two strands of DNA; each strand is a polymer of DNA nucleotides. Each nucleotide consists of a sugar, a phosphate group, and one of four nitrogenous bases. The structure and orientation of the two strands are important to understanding DNA replication. a) 5' end
b) hydrogen bond
c) 3' end
d) deoxyribose sugar
e) nitrogenous base
f) phosphate group
g) 3' end
h) 5' end