Question 1

Which of the following is NOT a characteristic of hereditary material as described in the study materials?

Accepted Answer

It is unable to accurately replicate itself, leading to frequent errors in daughter cells.

Question 2

Frederick Griffith’s experiment with Pneumococcus bacteria provided indirect evidence that DNA is the hereditary molecule. What was the key observation from his experiment?

Accepted Answer

Heat-killed S strain bacteria could transform live R strain bacteria into S strain, causing fatal pneumonia in mice.

Question 3

Which experiment provided direct evidence that DNA is the transformation factor responsible for heredity?

Accepted Answer

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

Question 4

In the Hershey-Chase experiment, what was the main conclusion regarding the hereditary material?

Accepted Answer

DNA is responsible for bacteriophage infection of bacteria cells.

Question 5

Which of the following correctly describes the structure of the DNA double helix?

Accepted Answer

The bases of one strand are complementary to the bases in the corresponding strand.

Question 6

Which base pairs are formed in DNA according to the rules of complementary pairing?

Accepted Answer

A pairs with T, and G pairs with C.

Question 7

What is the diameter of B-form DNA across the axis of symmetry?

Accepted Answer

$$20\mathrm{\AA}$$

Question 8

Which form of DNA is most commonly found in cells?

Accepted Answer

B-form

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 bacterial DNA replication, what is the function of the origin of replication (oriC)?

Accepted Answer

It is the sequence where replication-initiating enzymes bind to start DNA synthesis.

Question 12

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

Accepted Answer

DnaB helicase

Question 13

What is the role of RNA primers in DNA replication?

Accepted Answer

They provide a starting point for DNA polymerase to add nucleotides to the 3' end.

Question 14

Which strand is synthesized continuously during DNA replication?

Accepted Answer

Leading strand

Question 15

What is the function of DNA ligase during DNA replication?

Accepted Answer

It seals the gap among DNA segments after RNA primer removal.

Question 16

Which property of DNA polymerase allows it to correct occasional errors during replication?

Accepted Answer

3'-to-5' exonuclease activity

Question 17

Why is telomerase important in germ line cells?

Accepted Answer

It synthesizes repetitive telomere sequences to prevent chromosome shortening.

Question 18

Which of the following is a limitation of the polymerase chain reaction (PCR)?

Accepted Answer

It cannot amplify DNA fragments longer than 10 to 15 kb efficiently.

Question 19

What is the principle behind Sanger (dideoxynucleotide) DNA sequencing?

Accepted Answer

Incorporation of a dideoxynucleotide (ddNTP) terminates DNA synthesis at specific bases.

Question 20

Next-generation sequencing (NGS) differs from Sanger sequencing in which major way?

Accepted Answer

NGS sequences hundreds of thousands to millions of DNA fragments in parallel.

DNA Structure and Replication: Key Concepts and Experiments

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