Question 1

Which experiment provided the first strong evidence that DNA, and not protein, is the genetic material in cells?

Accepted Answer

Hershey-Chase experiment with bacteriophage T2

Question 2

What is the main chemical difference between the sugars in DNA and RNA?

Accepted Answer

DNA contains deoxyribose, which lacks an OH group at the 2' carbon, while RNA contains ribose with an OH at the 2' carbon

Question 3

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

Accepted Answer

$$20\%$$

Question 4

Which of the following best describes the structure of a DNA double helix?

Accepted Answer

Two antiparallel strands with a sugar-phosphate backbone on the outside and paired bases on the inside

Question 5

What is the function of topoisomerases in prokaryotic cells?

Accepted Answer

They wind and unwind DNA to relieve supercoiling stress

Question 6

Which of the following statements about nucleosomes is correct?

Accepted Answer

A nucleosome consists of 146 base pairs of DNA wrapped around eight histone proteins

Question 7

Which base is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 8

A scientist isolates a virus with a genome that is single-stranded RNA. Which of the following is true about this virus?

Accepted Answer

Its genome can be either linear or circular

Question 9

Which of the following best explains why proteins were originally thought to be the genetic material instead of DNA?

Accepted Answer

Proteins are composed of 20 different amino acids, making them more complex than DNA, which has only 4 bases

Question 10

Which of the following is a correct description of a phosphodiester bond in DNA?

Accepted Answer

A covalent bond joining the phosphate group at the 5' carbon of one nucleotide to the OH group at the 3' carbon of the next nucleotide

Question 11

In the Hershey-Chase experiment, why was $$^{32}P$$ used to label DNA and $$^{35}S$$ used to label protein?

Accepted Answer

DNA contains phosphorus but not sulfur, while proteins contain sulfur but not phosphorus

Question 12

Which of the following is NOT a difference between DNA and RNA?

Accepted Answer

DNA contains uracil, RNA contains thymine

Question 13

A mutation changes a single base in a gene from G to A. Which of the following is the most direct molecular consequence?

Accepted Answer

The sequence of the encoded RNA may change

Question 14

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

Accepted Answer

They are the result of the helical structure and provide access for proteins to interact with bases

Question 15

If a eukaryotic chromosome contains 1.47 x $$10^8$$ base pairs, how many nucleosomes would you expect, assuming each nucleosome contains 147 base pairs?

Accepted Answer

$$1.0 	imes 10^6$

Question 16

Which of the following is a correct statement about the polarity of DNA strands?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5'

Question 17

Which of the following best explains the result of mixing heat-killed S strain bacteria with live R strain bacteria in Griffith's experiment?

Accepted Answer

A 'transforming principle' from the S strain converted R strain into virulent S strain

Question 18

Which of the following is a real-world application of understanding DNA supercoiling in bacteria?

Accepted Answer

Designing antibiotics that target bacterial topoisomerases

Question 19

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be DNA or RNA, single- or double-stranded, linear or circular

DNA as the Genetic Material: Discovery, Structure, and Organization

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