BIOS 1700 Lecture Notes - Lecture 27: Okazaki Fragments, Dna Polymerase, Dna Replication
6 Dec 2016
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Approach: secures accuracy, template (parent) strand creates daughter strand, dna synthesis grows at the 3" end. Moves 5" to 3": builds daughter strand based on complementary parings. Daughter str: dna + dntp > dna + ppi. How did scientists discover the semi-conservative approach: started off between two approaches, conservative and semi-conservative. Conservative stated that the old strand of dna magically creates a new young strand of dna: scientists used a radioactive isotope of nitrogen to distinguish the old strand from the new strand, meselson and stahl experiment. Used radioactive nitrogen (15n) to track the parent strand of dna: n-15 is heavier than n-14 because it has an extra neutron. Labeled the parent strand with 15n but allowed the daughter strand to form with the natural 14n. 15n but the daughter strand has the natural 14n: when spun in a centrifuge, the daughter dna molecules form a band with an intermediate density, replication is allowed to occur a second time.
