Dna Replication Essay

711 Words3 Pages
One may wonder how a single cell becomes two cells, and why this is ultimately important to life. For this essay, it would be much too difficult to discuss the process of cell division, which is the biological basis of life. That being said, this essay will examine more closely the precursor to cell division, also known as DNA replication. DNA replication is the process of copying a double-stranded DNA strand on a chromosome within a cell. The process, in its totality, is a sequence of three basic steps: initiation, elongation, and termination. The prediction of Watson and Crick’s semi-conservative hypothesis is that each of the two daughter double helixes, after one round of replication, should be made up of one old strand and one new strand. The conservative model predicts that after replication, one of the double helixes that result would be entirely old. The daughter helixes would be entirely new. Finally, the dispersive model predicts that both the daughter and parental helixes would be made up of just a mixture of old and new DNA. The Meselson-Stahl experiment was an important step in developmental biology research. Two scientists, Matthew Meselson and Franklin Stahl carried out their experiment in 1958 to prove the semiconservative DNA replication hypothesis proposed by James Watson and Francis Crick. Much of what is known about DNA replication comes from work with bacteria. More than a dozen enzymes and other proteins participate in DNA replication. Much more is known about how this “replication machine” works in bacteria (such as E. coli) than in eukaryotes. What scientists have learned about eukaryotic DNA replication suggests however that most of the process is fundamentally similar for prokaryotes and eukaryotes. The replication of DNA molecule begins at particular sites called origins of replication, short stretches of DNA having specific sequences

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