The key to how DNA works resides in its structure and in how it duplicates
	• In 1957, Matthew Meselson and Franklin Stahl did an experiment to determine which of the following models best represented DNA replication: • 1.  Did the two strands unwind and each act as a template for new strands? This is semi-conservative replication, because each new strand is half comprised of molecules from the old strand. • 2.  Did the strands not unwind, but somehow generate a new double stranded DNA copy of entirely new molecules? This is conservative replication.