Question 1

Which of the following is NOT a characteristic of hereditary material as described in modern genetics?

Accepted Answer

It is always composed of proteins.

Question 2

Edmund Wilson’s early suggestion that DNA might be the hereditary material was based on which observation?

Accepted Answer

Sperm and eggs contribute the same number of chromosomes during reproduction.

Question 3

In Frederick Griffith’s experiment with Pneumococcus, what was the key finding that led to the concept of a 'transformation factor'?

Accepted Answer

Heat-killed S strain could transform live R strain into a virulent form.

Question 4

Which experiment provided direct evidence that DNA is the hereditary molecule responsible for transformation?

Accepted Answer

Avery, MacLeod, and McCarty’s in vitro transformation experiment.

Question 5

The Hershey-Chase experiment demonstrated that DNA, not protein, is responsible for bacteriophage infection. What radioactive isotopes did they use to label DNA and protein, respectively?

Accepted Answer

Phosphorus-32 for DNA and Sulfur-35 for protein.

Question 6

Which of the following correctly describes the antiparallel nature of DNA strands?

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'.

Question 7

Which base pairing rule is correct for DNA?

Accepted Answer

$$A$$ pairs with $$T$$ and $$G$$ pairs with $$C$$

Question 8

Which form of DNA is most commonly found in cells and has a right-handed helix?

Accepted Answer

B-form DNA

Question 9

What is the significance of major and minor grooves in the DNA double helix?

Accepted Answer

They are regions where DNA binding proteins can make direct contact with nucleotides.

Question 10

Which model of DNA replication was supported by the Meselson-Stahl experiment?

Accepted Answer

Semiconservative replication

Question 11

In E. coli, what is the name of the origin of replication and what is its key sequence feature?

Accepted Answer

oriC; contains A-T rich regions and conserved 13-mer and 9-mer sequences

Question 12

Which enzyme is responsible for unwinding the DNA helix during replication in E. coli?

Accepted Answer

DnaB helicase

Question 13

Why are RNA primers necessary for DNA replication?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end of an existing strand.

Question 14

What is the difference between leading and lagging strand synthesis during DNA replication?

Accepted Answer

Leading strand is synthesized continuously, lagging strand is synthesized discontinuously as Okazaki fragments.

Question 15

Which enzyme removes RNA primers and replaces them with DNA nucleotides in E. coli?

Accepted Answer

DNA polymerase I

Question 16

What is the function of the sliding clamp in DNA replication?

Accepted Answer

It anchors DNA polymerase to the template, increasing processivity.

Question 17

DNA polymerase proofreading is due to which enzymatic activity?

Accepted Answer

3'-to-5' exonuclease activity

Question 18

What problem does telomerase solve in eukaryotic chromosome replication?

Accepted Answer

It synthesizes repetitive sequences at chromosome ends to prevent loss of genetic information.

Question 19

Which step in the polymerase chain reaction (PCR) involves heating the reaction mixture to denature the DNA?

Accepted Answer

Denaturation

Question 20

In Sanger (dideoxynucleotide) DNA sequencing, what is the role of ddNTPs?

Accepted Answer

They terminate DNA chain elongation when incorporated.

DNA Structure and Replication: Foundations of Genetic Material

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