BIOL 3000 Lecture Notes - Lecture 9: Semiconservative Replication, Theta, Zygote
5 Feb 2017
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9. 1 genetic info. must be accurately copied every time a cell divides. A single-celled human zygote contains 6. 4 base pairs of dna. If a copying error was made only once per million base pairs, 6400 mistakes would be made every time cell divides. Copying of dna must be accurate and take place at a quick speed. 9. 2 all dna replication takes place in a semiconservative manner. Semiconservative replication each of the original nucleotide strands remain intact even though they are no longer being combined in the same molecule; the original dna molecule is half conserved during replication. They needed a way to distinguish old and new dna of e. coli to see which of the three models of dna replication applied. They used two isotopes of nitrogen, 14n and 15n. Meselson and stahl found that dna from bacteria grown only on medium containing 15n produced a single band at the position expected of dna containing only 15n.
