1) A mononucleotide is the monomer unit that makes up nucleic acids. It consists of a phosphate group, a pentose sugar (either deoxyribose in DNA or ribose in RNA), and a nitrogenous base. 2) In DNA, the four nitrogenous bases are adenine, guanine, cytosine, and thymine. In RNA, uracil replaces thymine. The bases bond through hydrogen bonding in a complementary way, with adenine bonding to thymine/uracil and cytosine bonding to guanine. 3) Nucleotides bond together through phosphodiester bonds between the phosphate of one nucleotide and the sugar of the next, forming the backbone of the