IUB BIOL-L 211 - Replication I (3 pages)
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Replication I
- Lecture number:
- 8
- Pages:
- 3
- Type:
- Lecture Note
- School:
- Indiana University, Bloomington
- Course:
- Biol-L 211 - Molecular Biology
- Edition:
- 1
Unformatted text preview:
BIOL L 211 Lecture 8 Outline of Last Lecture I Articles II Histones III The Nucleosome Outline of Current Lecture I Replication Hypotheses II Meselson Stahl Experiment III Methods and Minutia of DNA Replication Current Lecture Replication I I Replication Hypotheses A Dispersive Model Proposed that parental DNA strands fragmented and then served as templates B Semiconservative Model Proposed that DNA unzipped yielding two identical template strands which then served as templates for new DNA 1 Watson and Crick from earlier lectures preferred this model C Conservative Model parental strands of DNA remained together throughout replication II Meselson Stahl Experiment A Purpose Discover mechanism for DNA replication B Procedure 1 Bacteria grown in media with nucleotide precursors labeled with a heavy isotope of Nitrogen 15N 2 Bacteria then transferred to media with 14N precursors light isotope These 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 3 Bacteria allowed to grow in 14N solution 4 Three samples placed in ultracentrifuge through a CsCl gradient a DNA now separated by density 5 Observe C Results After two generations the semiconservative model proved to be accurate III Methods and Minutia of DNA Replication A Origins of Replication 1 Prokaryotes have ONE 2 Eukaryotes have hundreds to thousands 3 Pre Replication Complex melts DNA strands apart at origins of replication a Specialized proteins find the origins of replication B The Replication Fork 1 DNA synthesizes in two directions toward and away from the replication fork but still 5 3 both ways a Leading Strand synthesized toward with the replication fork b Lagging Strand synthesized piece Okazaki fragment by piece in the direction opposite the replication fork 2 Helicases rings that unwind DNA requiring ATP hydrolysis 3 Primases enzymes that add primers to single stranded DNA a Primers starting point for DNA
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