Question 1

Which of the following best describes the function of the nuclear lamina?

Accepted Answer

It is a thin network of intermediate filaments that provides structural support to the nuclear envelope.

Question 2

A mutation in the gene encoding lamin A can lead to which of the following diseases, characterized by premature aging?

Accepted Answer

Progeria

Question 3

Which of the following statements about the nuclear pore complex (NPC) is CORRECT?

Accepted Answer

The NPC is composed of multiple proteins called nucleoporins and is arranged in an octagonal pattern.

Question 4

Which of the following sequences is most likely to function as a nuclear localization signal (NLS)?

Accepted Answer

$$	ext{PKKKRKV}$$

Question 5

What is the primary role of RanGTP in nuclear import?

Accepted Answer

It binds to importin in the nucleus, causing the release of the cargo protein.

Question 6

Which of the following best explains why the nucleolus is not surrounded by a membrane?

Accepted Answer

It is formed by liquid-liquid phase separation (LLPS) and functions as a dynamic, membrane-less organelle.

Question 7

Which of the following is a direct consequence of a mutation causing a premature stop codon in the gene encoding the beta subunit of laminin?

Accepted Answer

Weak adhesion between the epidermis and underlying layers, leading to easy blistering (junctional epidermolysis bullosa).

Question 8

Which of the following processes occurs in the nucleolus?

Accepted Answer

Transcription and processing of rRNA and assembly of ribosomal subunits.

Question 9

Which enzyme is responsible for relaxing supercoiled DNA by introducing transient single-strand breaks?

Accepted Answer

Type I topoisomerase

Question 10

A researcher observes that a protein shuttles between the nucleus and cytoplasm. Which experimental approach could best demonstrate this phenomenon?

Accepted Answer

Interspecies heterokaryon analysis using GFP-fusion proteins and protein synthesis inhibitors.

Question 11

Which of the following best describes the directionality of nuclear transport?

Accepted Answer

It is determined by the RanGTP/GDP gradient, with RanGEF in the nucleus and RanGAP in the cytoplasm.

Question 12

Which of the following is TRUE regarding the organization of chromatin in the nucleus?

Accepted Answer

Each chromosome occupies a discrete territory within the nucleus, as shown by in situ hybridization.

Question 13

Which of the following is a function of the nuclear pore complex (NPC)?

Accepted Answer

It allows the selective exchange of macromolecules between the nucleus and cytoplasm.

Question 14

Which of the following best describes the flow of genetic information within a eukaryotic cell?

Accepted Answer

DNA is transcribed into mRNA in the nucleus, which is then translated into protein in the cytoplasm.

Question 15

Which of the following is a characteristic of the nucleolus?

Accepted Answer

It is the site of rRNA synthesis and ribosome assembly.

Question 16

Which of the following best explains why extensive supercoiling of DNA is important in cells?

Accepted Answer

It helps compact the DNA to fit within the limited space of the nucleus.

Question 17

Which of the following is a correct pairing of complementary DNA bases according to Chargaff’s rules?

Accepted Answer

Adenine with Thymine and Guanine with Cytosine

Question 18

Which of the following best describes the role of exportin in nuclear export?

Accepted Answer

It binds to proteins with a nuclear export signal (NES) and mediates their transport through the NPC in complex with RanGTP.

Question 19

Which of the following is the correct order of events for the import of a nuclear protein?

Accepted Answer

NLS-containing protein binds importin → docks at NPC → translocation through NPC → RanGTP binds importin and releases cargo

The Nucleus: Structure, Function, and Genetic Information Flow

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