BIOL 240 1st Edition Lecture 18Outline of Last Lecture I. Griffith’s Transformation ExperimentII. Life Cycle of T-even BacteriophageIII. Chemical Components of DNA and RNAIV. DNA StructureOutline of Current Lecture I. Replication Overview1. Formation of replication fork2. synthesis of leading strand3. synthesis of lagging strandCurrent LectureI. Replication Overview1. Formation of replication fork—two stands of DNA separate and are used as templates for new strands- proteins work together unwinding the DNA; DNA helicases bind and separate strands, while others break bonds and prevent bonds from reforming - DNA polymerases build new strands of DNA- since the parental strands run in opposite directions, the new strands are made differently2. Synthesis of Leading Strand- built continuously and toward the origin of replication- DNA polymerase builds a new DNA strand by adding nucleotides one at a time (nucleotides must pair with their complementary nucleotide)3. Synthesis of Lagging Strand- built discontinuously in pieces- Okasaki fragmentsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- since this is built in fragments, each piece begins with a short RNA segment called an RNA primer by RNA polymerase. Then, a clamp surrounds the RNA primer and attaches to DNA polymerase and builds the rest of the fragment as DNA. Once complete, it is released from the polymerase.- once all the pieces are complete, there are still those RNA segments between the DNA segments. How are they replaced?- a different DNA polymerase removes the RNA and replaces it with DNA- DNA ligase is the cement that joins the pieces
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