Understanding Meselson and Stahl

What was the main objective of the Meselson and Stahl experiment?

• To analyze protein synthesis in cells.

• To identify the structure of RNA.

• To determine the mechanism of DNA replication.

• To explore the effects of UV radiation on DNA.

Define conservative replication in DNA.

• Conservative replication results in two identical DNA molecules that are both original strands.

• Conservative replication is a model of DNA replication where the original DNA molecule remains unchanged and a new copy is created.

• Conservative replication is a process where both strands of DNA are copied simultaneously.

• Conservative replication involves the complete breakdown of the original DNA strand.

Define semi-conservative replication in DNA.

• Semi-conservative replication involves the complete copying of both strands without any original material.

• Semi-conservative replication is a method of DNA replication where each new double helix contains one original strand and one newly synthesized strand.

• DNA replication occurs in a conservative manner, preserving both original strands.

• Each new double helix contains two original strands.

What isotopes were used by Meselson and Stahl in their experiment?

• Nitrogen-15 and Nitrogen-14

• Oxygen-16 and Oxygen-18

• Carbon-12 and Carbon-14

• Hydrogen-1 and Hydrogen-2

How did Meselson and Stahl distinguish between the different DNA strands?

• They used X-ray crystallography to analyze DNA structure.

• They applied polymerase chain reaction to amplify DNA samples.

• They used density gradient centrifugation with heavy and light nitrogen isotopes.

• They utilized fluorescence microscopy to visualize DNA strands.

What were the results of the Meselson and Stahl experiment?

• DNA replication is semi-conservative.

• DNA replication is conservative.

• DNA replication occurs in a circular manner.

• DNA replication is dispersive.

Explain the significance of the semi-conservative model of DNA replication.

• It allows for the complete degradation of the original DNA strand.

• The semi-conservative model of DNA replication ensures genetic stability and accuracy by producing DNA molecules with one original and one new strand.

• The semi-conservative model produces two identical new strands of DNA.

• The model is only relevant in prokaryotic organisms.

What is the role of DNA polymerase in replication?

• DNA polymerase synthesizes new DNA strands and ensures accuracy during replication.

• DNA polymerase initiates transcription of RNA.

• DNA polymerase transports amino acids during protein synthesis.

• DNA polymerase repairs damaged DNA strands.

How does the conservative model differ from the semi-conservative model?

• The conservative model conserves both original strands, while the semi-conservative model conserves one original strand in each new DNA molecule.

• The conservative model uses both strands for replication, while the semi-conservative model uses none.

• The conservative model results in two identical copies, while the semi-conservative model results in one identical and one new strand.

• Both models conserve one original strand, but the conservative model does it more efficiently.

What type of organism was used in the Meselson and Stahl experiment?

• Staphylococcus aureus

• Saccharomyces cerevisiae (yeast)

• Bacillus subtilis

• Escherichia coli (E. coli)