STUDY QUESTIONS: DNA Structure and Replication

How are the two strands of DNA oriented relative to each other in the double helix?

• The two strands are parallel, running in the same direction.

• The two strands are anti-parallel, meaning one runs 5' to 3' and the other runs 3' to 5'.

• The two strands are coiled in opposite directions.

• The two strands are oriented randomly without any specific direction.

What element was used to tag the coating of the bacteriophage in the Hersey and Chase experiment?

• Phosphorus

• Sulfur

• Carbon

• Oxygen

Describe the directionality of a DNA strand.

• DNA strands are oriented from 3' to 5'.

• DNA strands have directionality, with one end being the 5' end and the other being the 3' end.

• DNA strands are always circular in structure.

• DNA strands do not have any specific directionality.

What is semi-conservative replication, and why is it important for DNA replication?

• It means each new DNA molecule contains two new strands, which increases mutation rates.

• It means each new DNA molecule contains one old and one new strand, ensuring accuracy.

• It refers to the process of DNA being replicated in a conservative manner, preserving the original strand.

• It indicates that DNA replication occurs only in the presence of certain enzymes.

What element was used to tag the material inside the bacteriophage in the Hersey and Chase experiment?

• Carbon

• Nitrogen

• Phosphorus

• Sulfur

What is the function of DNA polymerase I?

• Removes the RNA primers that were laid down for DNA polymerase III to create a new strand and replaces them with DNA nucleotides.

• Synthesizes RNA primers for DNA replication.

• Replicates the entire DNA strand during cell division.

• Acts as a proofreader for DNA replication.

Explain the role of ligase in DNA replication.

• Ligase unwinds the DNA helix to allow replication.

• Ligase joins Okazaki fragments together to create a continuous DNA strand.

• Ligase synthesizes RNA primers for DNA replication.

• Ligase separates the two strands of DNA during replication.

What is the role of hydrogen bonds in DNA structure?

• Hydrogen bonds hold the two strands of DNA together by pairing complementary bases.

• Hydrogen bonds provide energy for DNA replication.

• Hydrogen bonds prevent mutations in DNA sequences.

• Hydrogen bonds are responsible for the color of DNA.

Explain the concept of base pairing in DNA. Which bases pair together and how many hydrogen bonds do they form?

• Adenine pairs with thymine (2 hydrogen bonds), and guanine pairs with cytosine (3 hydrogen bonds).

• Adenine pairs with cytosine (2 hydrogen bonds), and guanine pairs with thymine (3 hydrogen bonds).

• Thymine pairs with guanine (2 hydrogen bonds), and cytosine pairs with adenine (3 hydrogen bonds).

• Adenine pairs with thymine (3 hydrogen bonds), and guanine pairs with cytosine (2 hydrogen bonds).

What is the shape of a DNA molecule, and who first proposed this model?

• A. Single helix, proposed by Rosalind Franklin

• B. Double helix, proposed by James Watson and Francis Crick

• C. Triple helix, proposed by Linus Pauling

• D. Circular, proposed by Gregor Mendel