Meselson and stahl cultured e coli for several generations...

Meselson and Stahl cultured E. coli for several generations in a medium with a heavy isotope of nitrogen, 15N. They transferred the bacteria to a medium with a light isotope of nitrogen, 14 N. After two rounds of DNA replication, half the DNA molecules were light (both strands had 14N) and half were hybrids (15N-14N). What did the researchers conclude from these results? DNA replication is semiconservative. Opposite DNA strands are complementary to each other. The nitrogenous bases in DNA molecules incorporate both 15N and 14N.

Transcript

0:00 Hello everyone.

00:01 The question says that meselson and stahl cultured e.

00:04 Coli for several generations in a medium with a heavy isotope of nitrogen, which is the 15n.

00:11 They transferred the bacteria to a medium with a light isotope of nitrogen, which is 14n.

00:17 After two rounds of dna replication, half the dna molecules were light, that is, both strands had 14n and half were hybrids, that is 15n and 14n.

00:28 What did the researchers conclude? from these results.

00:33 So the results of messilsen and stahl experiment, it can be explained by the semi -conservative model.

00:41 Okay, now in semi -conservative model what happens is if this is the structure of the dna, then when the replication it happens, one of the strand, it will be conserved and then there will be the formation of the new strand.

01:05 Okay, so one strand it will always be conserved.

01:09 All right.

01:09 So, this is known as the semi -conservative type of replication.

01:14 So, this mesolson and styles experiment can be explained by semi -conservative mode of dna replication.

01:21 So, according to it, the two dna strands separate and both are used for synthesis of the new dna strands such that the new dna molecule has one parental and one new strand.

01:31 Okay.

01:32 So in the experiment originally the medium was 15n.

01:38 The medium was 15n...

Question

Please give Ace some feedback