DNA Replication: mechanism, enzymes, evidences in favor of semi conservative replication
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Introduction:- > Replication is the copying of DNA from parental DNA. > Watson & Crick proposed Semi-conservative model of replication. It suggests that the parental DNA strands act as template for the synthesis of new complementary strands. After the completion of replication, each DNA molecule would have one parental and one new strand. Evidences in favor of semi conservative replication:- Matthew Messelson & Franklin Stahl (1958) experimentally proved Semi-conservative model. > They cultured E. coli in a medium containing 15NH4Cl (15N: heavy isotope of N). 15N was incorporated into both strands of bacterial DNA and the DNA became heavier. > Another preparation containing N salts labeled with 14N is also made. 14N was also incorporated in both strands of DNA and became lighter. > These 2 types of DNA can be separated by centrifugation in a CsCl density gradient. > They took E. coli cells from 15N medium and transferred to 14N medium. > After one...