Question 1

Which experiment first demonstrated the concept of bacterial transformation, and what was the key finding?

Accepted Answer

Griffith's experiment; he observed that nonvirulent bacteria could become virulent by interacting with heat-killed virulent bacteria.

Question 2

In the Avery, MacLeod, and McCarty experiment, which enzyme treatment prevented transformation and what does this indicate about the transforming principle?

Accepted Answer

DNase treatment; indicates DNA is the transforming principle.

Question 3

Why did Hershey and Chase use $$^{32}P$$ and $$^{35}S$$ isotopes in their experiment with T2 bacteriophage?

Accepted Answer

$$^{32}P$$ labels DNA and $$^{35}S$$ labels protein, allowing them to distinguish which molecule enters the bacteria.

Question 4

What was the conclusion of the Hershey-Chase experiment regarding the genetic material of bacteriophages?

Accepted Answer

DNA is the genetic material because $$^{32}P$$ was found inside the bacteria and passed to progeny phages.

Question 5

Which chemical bond links nucleotides together in DNA and why is this bond important for DNA stability?

Accepted Answer

Phosphodiester bond; it is covalent and provides remarkable stability to DNA.

Question 6

Which pair of nitrogenous bases forms the most stable bond in DNA and why?

Accepted Answer

Guanine and Cytosine; they form three hydrogen bonds.

Question 7

Which of the following best describes the structure of DNA as proposed by Watson and Crick?

Accepted Answer

Double-stranded, right-handed helix with sugar-phosphate backbone on the outside and bases paired in the center.

Question 8

According to Chargaff’s rules, if a DNA sample contains 30% adenine, what percentage of guanine would you expect?

Accepted Answer

20%

Question 9

Which feature distinguishes RNA from DNA at the molecular level?

Accepted Answer

RNA contains ribose sugar, while DNA contains deoxyribose.

Question 10

A mutation in the II-R strain of Streptococcus pneumoniae prevents capsule formation. What is the consequence for the bacteria’s virulence?

Accepted Answer

The bacteria lose virulence because they are easily defeated by the host immune system.

Question 11

Which of the following best explains why DNA is suitable as the genetic material in forensic science?

Accepted Answer

DNA is stable due to strong phosphodiester bonds, allowing it to persist in harsh conditions.

Question 12

Which of the following is NOT a component of a nucleotide?

Accepted Answer

Peptide bond

Question 13

What is the significance of the antiparallel arrangement of DNA strands?

Accepted Answer

It enables complementary base pairing and proper replication.

Question 14

Which process describes the integration of viral DNA into the host genome, allowing it to be passed to subsequent generations?

Accepted Answer

Lysogenic cycle

Question 15

Which chemical formula represents the phosphodiester bond between two nucleotides?

Accepted Answer

$$	ext{Covalent bond between the 5' phosphate group of one nucleotide and the 3' hydroxyl group of another}$$

Question 16

Which amino acid structure is common to all amino acids?

Accepted Answer

$$	ext{Central carbon, carboxyl group, amino group, and R group}$$

Question 17

Which of the following best describes the major and minor grooves in the DNA double helix?

Accepted Answer

They are formed by the unequal spacing of sugar-phosphate backbones and are important for protein binding.

Question 18

Which of the following is a real-world application of the stability of DNA?

Accepted Answer

DNA is used in forensic science because it can be boiled or autoclaved without degrading.

Question 19

Which of the following statements about polynucleotide chains is correct?

Accepted Answer

The 5' end has a free phosphate group, and the 3' end has a free hydroxyl group.

The Molecular Basis of Genetic Material: DNA, RNA, and Protein Structure

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