Question 1

Which experiment provided the first direct evidence that DNA is the genetic material in bacteria?

Accepted Answer

Avery, MacLeod, and McCarty's experiment with Streptococcus pneumoniae

Question 2

In Griffith's transformation experiment, what happened when heat-killed virulent (IIIS) cells were mixed with living avirulent (IIR) cells and injected into mice?

Accepted Answer

The mice died, and living IIIS cells were recovered from the tissue.

Question 3

Which chemical property of DNA allows it to absorb UV light most strongly at 260 nm?

Accepted Answer

The aromatic rings in the nitrogenous bases

Question 4

What is the significance of Chargaff's rules in understanding DNA structure?

Accepted Answer

They demonstrated that the amount of adenine equals thymine and guanine equals cytosine.

Question 5

Which bond links nucleotides together in a DNA strand?

Accepted Answer

Phosphodiester bond

Question 6

If a DNA molecule has 30% adenine, what percentage of guanine would you expect according to Chargaff's rules?

Accepted Answer

20%

Question 7

Why does the melting temperature ($$T_m) of $$DNA increase with higher G-C content?

Accepted Answer

G-C pairs form three hydrogen bonds, making the DNA more stable.

Question 8

Which of the following is NOT a characteristic required of genetic material?

Accepted Answer

Ability to catalyze chemical reactions

Question 9

What is the main difference between a nucleoside and a nucleotide?

Accepted Answer

A nucleoside contains a nitrogenous base and a sugar, while a nucleotide also contains one or more phosphate groups.

Question 10

Which analytic technique is used to separate DNA fragments by size?

Accepted Answer

Gel electrophoresis

Question 11

In the Hershey-Chase experiment, which isotope was used to label DNA?

Accepted Answer

$$^{32}P$$

Question 12

Which structural feature of DNA ensures a constant diameter of the double helix?

Accepted Answer

Pairing of one purine with one pyrimidine

Question 13

What is the function of molecular hybridization techniques such as FISH?

Accepted Answer

To identify complementary DNA sequences

Question 14

Which of the following statements about DNA structure is correct?

Accepted Answer

The two strands are antiparallel and held together by complementary base pairing.

Question 15

A mutation changes a DNA sequence from 5'-ATGCGT-3' to 5'-ATGAGT-3'. Which type of mutation is this?

Accepted Answer

Point mutation

Question 16

Which property of DNA allows it to serve as the genetic material for both mitochondria and chloroplasts?

Accepted Answer

DNA is found in both organelles and can be replicated independently.

Question 17

What is the effect of treating a DNA sample with DNase in Avery, MacLeod, and McCarty's experiment?

Accepted Answer

Transformation does not occur because DNA is destroyed.

Question 18

Which of the following best describes the hyperchromic shift observed in DNA analysis?

Accepted Answer

Increase in UV absorbance as DNA transitions from double-stranded to single-stranded

Question 19

Which of the following is a pyrimidine found in DNA?

Accepted Answer

Thymine

Question 20

Why do gametes contain half the amount of DNA compared to somatic cells?

Accepted Answer

Gametes are haploid, containing one set of chromosomes.

DNA Structure and Analysis: Foundations of Molecular Genetics

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