Exploring DNA: History, Structure, and Replication

The video lecture covers the history, structure, and replication of DNA. It begins with the discovery of DNA as the genetic material through experiments by Griffith, Avery, and the Hershey-Chase experiment. The structure of DNA is explained, highlighting contributions from scientists like Chargaff, Franklin, Watson, and Crick. The lecture concludes with a detailed explanation of DNA replication, including the roles of helicase and polymerase enzymes.

What did scientists in the early 1900s know about genetic information?

• It was carried in the cell membrane.

• It was carried in ribosomes.

• It was carried in mitochondria.

• It was carried in chromosomes.

What was Frederick Griffith's conclusion from his experiments with pneumonia-causing bacteria?

• Heat-killed bacteria cannot affect living organisms.

• Living organisms can pass genetic information from one to another.

• Proteins are the carriers of genetic information.

• Genetic information is not passed between bacteria.

What did Hershey and Chase use to label the DNA and protein parts of the virus?

• Radioactive calcium and magnesium

• Radioactive carbon and nitrogen

• Radioactive sulfur and phosphorus

• Radioactive oxygen and hydrogen

What did Hershey and Chase conclude from their experiments?

• Bacteria do not carry genetic information.

• Viruses do not carry genetic information.

• DNA is the carrier of genetic information.

• Proteins are the carriers of genetic information.

What did Chargaff discover about the nitrogen bases in DNA?

• Cytosine and guanine are always unequal in amount.

• Adenine and thymine are always equal in amount.

• Thymine and guanine are always unequal in amount.

• Adenine and cytosine are always equal in amount.

What was Rosalind Franklin's major contribution to the understanding of DNA?

• She discovered the process of DNA replication.

• She discovered the role of DNA in genetic inheritance.

• She discovered the four nitrogen bases.

• She discovered the double helix structure of DNA.

What is the structure of DNA according to Watson and Crick?

• A triple helix

• A double helix

• A quadruple helix

• A single helix

What are the components of a nucleotide?

• A sugar, a phosphate, and a nitrogen base

• A sugar, a carbohydrate, and a nitrogen base

• A sugar, a lipid, and a nitrogen base

• A sugar, a protein, and a nitrogen base

What is the role of DNA helicase in DNA replication?

• It adds new nucleotides to the DNA strand.

• It unwinds and unzips the DNA molecule.

• It synthesizes new DNA strands.

• It repairs damaged DNA.

What is the semi-conservative model of DNA replication?

• Each new DNA molecule has three new strands.

• Each new DNA molecule has two new strands.

• Each new DNA molecule has one old and one new strand.

• Each new DNA molecule has two old strands.