MCB 250 Lecture Notes - Lecture 3: Ester, Polynucleotide, Phosphodiester Bond

• School: University of Illinois
• Department: Molecular and Cell Biology
• Course: MCB 250
• Professor: J Slauch

Document Summary

N-glycosidic bond: nucleotides are, in turn, joined to each other in polynucleotide chains through the 3"-hydroxyl of. This polarity is designed by the asymmetry of the nucleotides and the way they are joined. 5"-phosphate or 5"-hydroxyl at one end and a free 3"-phosphate or 3"-hydroxyl at the other end. Each base has its preferred tautomeric form: each of the bases exists in two alternative tautomeric states, which are in equilibrium with each other. The equilibrium lies far to the side of the conventional structures, which are the predominant states and the ones important for vase pairing. The nitrogen atoms attached to the purine and pyrimidine rings are in the amino form in the predominant states and only rarely assume the imino configuration. The two chains of the double helix have complementary sequences: the pairing between adenine and thymine, and between guanine and cytosine, results in a complementary relationship between the sequence of bases on the two intertwined chains and gives.