BIOL 2311 Lecture Notes - Lecture 12: Nitrogenous Base, Base Pair, Thymidine Triphosphate

• School: UT-Dallas
• Department: Biology
• Course: BIOL 2311
• Professor: Srikanth Uma

Document Summary

Meselson and stahl distinguished parental dna strands from newly synthesized dna using a nonradioactive heavy nitrogen. The junction of the unwound molecules is a replication fork. A new strand is formed by pairing complementary bases with the old strand. Each has one new and one old dna strand. A nucleoside triphosphate is a nitrogenous base linked to a sugar, which is linked, in turn, to a chain of three phosphate groups (see figure 3. 24). Deoxyribonucleoside triphosphates are the substrates catalyzed by dna polymerase four different deoxyribonucleoside triphosphates (datp, dgtp, dctp, and dttp) are used for dna replication. Dna polymerase forms a complementary base pair (the replicated strand) by catalyzing the deoxyribonucleoside triphosphates (substrates) by adding these substrates only to the 3" end of an existing nucleotide chain. As a new dna strand is assembled, a 3" oh group is always exposed at its newest end. Oldest end has triphosphate at the 5" end.