# <HELP> One question about Meselson-Stahl experiment

• SAT2400
In summary, the Meselson-Stahl experiment tests various hypotheses about DNA replication. According to the semi-conservative and dispersive hypotheses, after the first replication, there should be a single, medium-density band. The conservative hypothesis predicts a single, medium-density band after the second replication. Both the semi-conservative and conservative models expect two bands (one high-density, one low density) after the first replication. The dispersive hypothesis predicts two bands after the first replication. Therefore, the correct answer is E, none of the above. It is important to note that the experimental results actually supported the semi-conservative model, with one medium-density band after the first replication and two bands (one high-density, one low density) after the second replication
SAT2400

## Homework Statement

In the Meselson-Stahl experiment, which banding pattern expected by which hypothesis/es would be the same?

A. A single, medium-density band after the first replication is expected by both the semi-conservative and the dispersive hypotheses.
B. A single, medium-density band after the second replication is expected by both the semi-conservative and the conservative hypotheses.
C. Two bands (one high-density, one low density) after the first replication is expected by both the semi-conservative model and the conserviative models
D. Two bands after the first replication are expected for both the conservative and the dispersive hypotheses.
E. None of the above.

## Homework Equations

Meselson-Stahl experiment

## The Attempt at a Solution

I think it's C, but my friend said it's A...

Could you explain why you think your answer is right?

More generally, what should happen after each replication (first, second) under each of the three hypotheses? That's only 6 things, you should be able to do that in one post.

## What is the Meselson-Stahl experiment?

The Meselson-Stahl experiment, also known as the "replication experiment," was a landmark experiment conducted in 1958 by Matthew Meselson and Franklin Stahl to determine the mechanism of DNA replication.

## What were the main findings of the Meselson-Stahl experiment?

The main findings of the Meselson-Stahl experiment were that DNA replication is semiconservative, meaning that each new DNA molecule is composed of one original and one newly synthesized strand. This supported the theory proposed by Watson and Crick that DNA replication is a semi-conservative process.

## What was the significance of the Meselson-Stahl experiment?

The Meselson-Stahl experiment provided evidence for the semi-conservative model of DNA replication, which has since become the accepted understanding of how DNA replicates. This experiment also paved the way for further research on DNA replication and its role in biological processes.

## How was the Meselson-Stahl experiment conducted?

The Meselson-Stahl experiment involved using heavy nitrogen isotopes to label the DNA of E. coli bacteria. The bacteria were then allowed to replicate in a medium containing light nitrogen, and the density of the DNA was measured using centrifugation. This allowed for the differentiation of DNA molecules with different compositions, providing evidence for the semi-conservative nature of DNA replication.

## What were some criticisms of the Meselson-Stahl experiment?

Some scientists criticized the Meselson-Stahl experiment for not providing definitive proof of the semi-conservative model of DNA replication. They argued that the results could also be explained by other models, such as the dispersive model. However, subsequent experiments and research have confirmed the validity of the semi-conservative model proposed by the Meselson-Stahl experiment.

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