How well do you know the Meselson and Stahl Experiment?

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Questions and Answers

What did Watson and Crick propose about DNA replication?

The semiconservative model (correct)

The dispersive model

The hybrid model

The conservative model

What is the conservative model of DNA replication?

The two original strands rewind after replication. (correct)

Hybrid DNA molecules with one parental 15N strand and one new 14N strand.

Two DNA molecules, one with two 15N strands and one with two 14N strands.

Interspersed sections of both old and new DNA in daughter strands.

What did Meselson and Stahl's experiment involve?

Analyzing DNA samples from bacteria (correct)

Analyzing DNA samples from humans

Analyzing RNA samples from bacteria

Analyzing protein samples from bacteria

What was the result of Meselson and Stahl's experiment at generation 2?

Two DNA molecules, one with two 15N strands and one with two 14N strands. Signup and view all the answers

What was the result of Meselson and Stahl's experiment at generation 1?

Hybrid DNA molecules with one parental 15N strand and one new 14N strand. Signup and view all the answers

What model of DNA replication was ruled out by Meselson and Stahl's experiment?

The conservative model Signup and view all the answers

What did Meselson and Stahl's experiment provide evidence for?

The semiconservative model of DNA replication. Signup and view all the answers

Which model of DNA replication predicts that the two original strands rewind after replication?

Conservative model Signup and view all the answers

What did Meselson and Stahl use to label the DNA in their experiment?

Uniformly labeled 15N bases Signup and view all the answers

What was the predicted outcome of the conservative model of DNA replication in Meselson and Stahl's experiment?

Two DNA molecules, one with two 15N strands and one with two 14N strands Signup and view all the answers

What was the predicted outcome of the dispersive model of DNA replication in Meselson and Stahl's experiment?

Interspersed sections of both old and new DNA in daughter strands Signup and view all the answers

What was observed in the DNA samples at generation 1 in Meselson and Stahl's experiment?

One band containing hybrid DNA molecules Signup and view all the answers

What was observed in the DNA samples at generation 2 in Meselson and Stahl's experiment?

Two bands containing equal quantities of DNA, one with hybrid density and the other with the predicted density for DNA with two 14N strands Signup and view all the answers

What did Meselson and Stahl's experiment provide evidence for?

The semiconservative model of DNA replication Signup and view all the answers

Study Notes

Semiconservative DNA Replication: Meselson and Stahl Experiment

Watson and Crick proposed a semiconservative model of DNA replication in which each parental strand separates and serves as a template for a complementary strand.
The conservative model of replication predicts that the two original strands rewind after replication, while the dispersive model predicts interspersed sections of both old and new DNA in daughter strands.
Meselson and Stahl performed an experiment using Escherichia coli cultured in a heavy growth medium with uniformly labeled 15N bases, followed by transfer to a light growth medium containing 14N.
DNA samples were extracted at various generations and analyzed through cesium chloride equilibrium density gradient centrifugation.
At generation 0, all bacterial DNA was uniformly labeled with 15N and migrated as a single band in the gradient.
At generation 1, the semiconservative model predicted hybrid DNA molecules with one parental 15N strand and one new 14N strand, which was observed.
The conservative model predicted two DNA molecules, one with two 15N strands and one with two 14N strands, which was ruled out.
The dispersive model was not ruled out until generation 2, where the data was consistent with the semiconservative model and argued against the dispersive model.
At generation 2, two bands containing equal quantities of DNA were observed, one with the predicted hybrid density and the other with the predicted density for DNA with two 14N strands.
Generations 3 and 4 also supported the semiconservative model as the only one fully consistent with the data.
Meselson and Stahl's experiment provided evidence for the semiconservative model of DNA replication and helped establish its validity.
The experiment was performed just five years after the Watson-Crick model was proposed and demonstrated the importance of experimental evidence in validating scientific models.

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Description

Test your knowledge on the groundbreaking Meselson and Stahl experiment that provided evidence for the semiconservative model of DNA replication. Take this quiz to learn about the different models of DNA replication, the experimental design of Meselson and Stahl, and the significance of their findings. Keywords: semiconservative model, DNA replication, Meselson and Stahl, experiment, Watson and Crick, conservative model, dispersive model, Escherichia coli, cesium chloride equilibrium density gradient centrifugation