DNA Structure and Replication Concepts

The video explores the history of DNA as genetic material, starting with early misconceptions about proteins. It covers key experiments, including Griffith's bacterial transformation, Hershey and Chase's evidence for DNA, and Franklin's x-ray crystallography. The video concludes with the Meselson-Stahl experiment, demonstrating semiconservative DNA replication.

What was the initial belief about the genetic material before DNA was discovered?

• RNA was initially thought to be the genetic material.

• Lipids were believed to carry genetic information.

• Carbohydrates were considered the genetic material.

• Proteins were thought to be the genetic material.

What did Frederick Griffith's experiment demonstrate?

• Bacteria can transform harmless cells into harmful ones.

• RNA is the genetic material.

• Proteins are the genetic material.

• DNA is a double helix.

What was the key finding of the Hershey and Chase experiment?

• DNA is a single strand.

• Bacteria can transform harmless cells into harmful ones.

• Proteins contain phosphorus.

• DNA, not protein, is the genetic material.

What technique did Rosalind Franklin use to study DNA?

• Mass spectrometry

• Nuclear magnetic resonance

• Electron microscopy

• X-ray crystallography

What did Watson and Crick propose based on Rosalind Franklin's findings?

• The single strand structure of DNA

• The double helix structure of DNA

• The triple helix structure of DNA

• The circular structure of DNA

What is the significance of the double helix structure of DNA?

• It proves that DNA is a carbohydrate.

• It shows that DNA is a protein.

• It indicates that DNA is a lipid.

• It explains how DNA replicates.

What did Meselson and Stahl's experiment demonstrate about DNA replication?

• DNA replication is semi-conservative.

• DNA replication is conservative.

• DNA replication is dispersive.

• DNA replication is random.

In Meselson and Stahl's experiment, what isotopes were used to demonstrate DNA replication?

• Heavy and light nitrogen isotopes

• Heavy and light carbon isotopes

• Heavy and light oxygen isotopes

• Heavy and light hydrogen isotopes

What was the outcome of Meselson and Stahl's experiment after several generations?

• DNA had no strands from the parent molecule.

• DNA had one strand from the parent molecule.

• DNA was completely new with no parent strands.

• DNA was identical to the parent molecule.

Why is the semi-conservative model of DNA replication important?

• It prevents DNA from replicating.

• It allows for random mutations.

• It causes DNA to degrade over time.

• It ensures genetic consistency across generations.