Q: Which equation correctly represents the DNA packing ratio, given that the length of DNA in a human cell is approximately 5 feet and the diameter of the nucleus is about $$10 \ \mu m$$?

$$\text{Packing Ratio} = \frac{\text{Length of DNA}}{\text{Diameter of Nucleus}}$$

Question 1

Which experiment provided definitive evidence that DNA, and not protein, is the genetic material in bacteriophages?

Accepted Answer

Hershey-Chase experiment using radioactive isotopes

Question 2

According to Chargaff’s rules, which equation correctly represents the relationship between DNA bases in a double helix?

Accepted Answer

$$A = T$$ and $$G = C$$

Question 3

A scientist isolates a DNA sample and finds that it has a high melting temperature ($$T_m). $$Which of the following best explains this observation?

Accepted Answer

The DNA sample has a high proportion of guanine and cytosine.

Question 4

Which structural feature of DNA allows for accurate replication during cell division?

Accepted Answer

The antiparallel orientation and complementary base pairing

Question 5

In the context of chromatin structure, what is the function of histone H1?

Accepted Answer

It is involved in the formation of the 30-nm chromatin fiber.

Question 6

Which of the following best describes the process of nucleic acid hybridization as used in fluorescence in situ hybridization (FISH)?

Accepted Answer

Single-stranded DNA probes bind to complementary sequences in denatured DNA, allowing visualization with fluorescent dyes.

Question 7

Which equation correctly represents the DNA packing ratio, given that the length of DNA in a human cell is approximately 5 feet and the diameter of the nucleus is about $$10 \ \mu m$$?

Accepted Answer

$$	ext{Packing Ratio} = \frac{	ext{Length of DNA}}{	ext{Diameter of Nucleus}}$$

Question 8

Which histone modification is most commonly associated with transcriptionally active chromatin?

Accepted Answer

Acetylation of histone side chains

Question 9

A mutation disrupts the nuclear localization signal (NLS) of a protein. What is the most likely consequence?

Accepted Answer

The protein will fail to enter the nucleus and remain in the cytoplasm.

Question 10

Which of the following statements about telomeres is correct?

Accepted Answer

Telomeres contain highly repetitive DNA sequences that protect chromosome ends.

Question 11

Which of the following best describes the role of the nuclear pore complex (NPC)?

Accepted Answer

It regulates the transport of macromolecules between the nucleus and cytoplasm.

Question 12

Which type of chromatin is most likely to be transcriptionally active?

Accepted Answer

Euchromatin

Question 13

Which of the following is a structural feature unique to eukaryotic chromosomes that is essential for proper segregation during cell division?

Accepted Answer

Centromere

Question 14

Which equation best represents the relationship between the melting temperature ($$T_m) of $$DNA and its GC content?

Accepted Answer

$$T_m \propto 	ext{GC content}$$

Question 15

Which of the following best explains why DNA can be denatured and renatured?

Accepted Answer

DNA strands are held together by weak noncovalent bonds, allowing separation and reannealing.

Question 16

Which of the following is NOT a function of the nuclear envelope?

Accepted Answer

Synthesizing ribosomal RNA

Question 17

Which of the following best describes the composition of a nucleosome?

Accepted Answer

A histone octamer wrapped by 146 base pairs of DNA

Question 18

Which of the following statements about the human mitochondrial genome is correct?

Accepted Answer

It contains about 37 genes and is approximately 16,569 base pairs long.

Question 19

Which of the following best describes the function of the nucleolus?

Accepted Answer

It is the site of ribosomal subunit assembly.

Question 20

Which of the following is a plausible consequence of defects in nuclear lamina proteins?

Accepted Answer

Serious human diseases such as Progeria

DNA, Chromosomes, and the Nucleus: The Structural Basis of Cellular Information

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