$$\text{Nucleotide}_1 + \text{Nucleotide}_2 \rightarrow \text{Nucleotide}_1\text{-}$$Nucleotide_2$$ + H_2O$$

Question 1

Which experiment provided the first direct evidence that DNA is the genetic material in bacteria, and what was the key finding?

Accepted Answer

Avery, MacLeod, and McCarty experiment; DNase destroyed the transforming principle

Question 2

Which property is NOT required for a molecule to serve as genetic material?

Accepted Answer

Ability to catalyze metabolic reactions

Question 3

What is the chemical difference between ribose and deoxyribose, and how does this affect the structure of DNA and RNA?

Accepted Answer

Deoxyribose lacks an oxygen atom at the 2' carbon, making DNA less reactive

Question 4

Which equation correctly represents Chargaff’s rule for double-stranded DNA?

Accepted Answer

$$A = T$$

Question 5

A DNA molecule is composed of 30% adenine. According to Chargaff’s rules, what percentage of guanine would you expect?

Accepted Answer

20%

Question 6

Which of the following best describes the structure of B-DNA found in cells?

Accepted Answer

Right-handed helix, 10 bp per turn, 2 nm diameter

Question 7

Which chemical bond links nucleotides together in a single strand of DNA?

Accepted Answer

Phosphodiester bond

Question 8

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

Accepted Answer

It enables complementary base pairing and faithful replication

Question 9

Which nitrogenous bases are classified as purines?

Accepted Answer

Adenine and guanine

Question 10

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

Accepted Answer

32P; DNA is the genetic material

Question 11

Which of the following is a function of telomeres in eukaryotic chromosomes?

Accepted Answer

Stabilize chromosome ends and assist in replication

Question 12

Which equation represents the phosphodiester bond formation between two nucleotides?

Accepted Answer

$$	ext{Nucleotide}_1 + 	ext{Nucleotide}_2 ightarrow 	ext{Nucleotide}_1	ext{-}$$Nucleotide_2$$ + H_2O$$

Question 13

Which of the following statements about chromatin is correct?

Accepted Answer

Euchromatin is less condensed and often transcribed

Question 14

What is the role of histone H1 in nucleosome structure?

Accepted Answer

It binds linker DNA and clamps DNA onto the nucleosome core

Question 15

Which DNA structure is thought to be involved in gene expression and is a left-handed helix?

Accepted Answer

Z-DNA

Question 16

If a segment of DNA contains 40% guanine, what percentage of thymine would you expect?

Accepted Answer

10%

Question 17

Which of the following best explains why E. coli can fit its chromosome inside the cell despite its length?

Accepted Answer

The chromosome is circular, negatively supercoiled, and organized in twisted loops

Question 18

Which type of DNA sequence is most likely to be found at centromeres and telomeres?

Accepted Answer

Highly repetitive DNA

Question 19

Which of the following is a correct description of a nucleotide?

Accepted Answer

A nitrogenous base, a pentose sugar, and a phosphate group

DNA: The Chemical Nature of the Gene – Structure, Function, and Chromosomal Organization

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