Griffith's experiment worked with two types of pneumococcal bacteria (a rough type and a smooth type) and identified that a "transforming principle" could transform them from one type to another.
At first, bacteriologists suspected the transforming factor was a protein. The "transforming principle" could be precipitated with alcohol, which showed that it was not a carbohydrate. But Avery and McCarty observed that proteases (enzymes that degrade proteins) did not destroy the transforming principle. Neither did lipases (enzymes that digest lipids). Later they found that the transforming substance was made of nucleic acids but ribonuclease (which digests RNA) did not inactivate the substance. By this method, they were able to obtain small amounts of highly purified transforming principle, which they could then analyze through other tests to determine its identity, which corresponded to DNA.
The phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase.
<span>Blowflies burrow into the ground at the completion or, 4th instar stage (17 mm size,) of their larval growth. After burrowing into the ground, the larvae transform into the pupal stage. They remain underground in the pupal stage for 6 to 8 days at which time the adult fly emerges.</span>
