Question 1

Which of the following best describes the structure of the nuclear envelope?

Accepted Answer

Two unit membranes separated by a perinuclear space

Question 2

What is the primary function of the nuclear pore complex?

Accepted Answer

To regulate the transport of molecules between the nucleus and cytoplasm

Question 3

A protein destined for the nucleus contains a specific sequence that directs its import. What is this sequence called?

Accepted Answer

Nuclear Localization Signal (NLS)

Question 4

Which of the following best describes the function of the molecule 'importin'?

Accepted Answer

It binds to the NLS of cargo proteins and facilitates their transport into the nucleus

Question 5

A mutation disrupts the Nuclear Localization Signal (NLS) of a transcription factor. What is the most likely consequence?

Accepted Answer

The protein will accumulate in the cytoplasm and fail to regulate gene expression

Question 6

Which of the following statements about euchromatin and heterochromatin is correct?

Accepted Answer

Euchromatin is less condensed and associated with active transcription

Question 7

Which of the following is a defining feature of a nucleosome?

Accepted Answer

A segment of DNA wrapped around a core of histone proteins

Question 8

Which of the following best defines 'epigenetics'?

Accepted Answer

Heritable changes in gene expression that do not involve changes to the DNA sequence

Question 9

Which histone modification is most commonly associated with active chromatin?

Accepted Answer

Histone acetylation

Question 10

Which of the following marks is most likely to be found in heterochromatin?

Accepted Answer

Histone H3 lysine 9 methylation ($$H3K9me)$$

Question 11

A scientist treats cells with a drug that blocks histone acetyltransferase activity. What is the most likely effect on gene expression?

Accepted Answer

Decreased transcription due to more condensed chromatin

Question 12

Which of the following best describes the 'histone code' hypothesis?

Accepted Answer

Combinations of histone modifications regulate chromatin structure and gene expression

Question 13

A patient has a genetic disorder that impairs the function of exportins. Which cellular process is most likely to be affected?

Accepted Answer

Export of RNA and proteins from the nucleus to the cytoplasm

Question 14

Which of the following best explains why polar molecules require transport complexes to enter the nucleus?

Accepted Answer

The nuclear envelope is hydrophobic and impermeable to polar molecules

Question 15

Which of the following is most likely to be found in active chromatin?

Accepted Answer

Histone H3 lysine 4 methylation ($$H3K4me)$$

Question 16

A researcher observes that a gene is silenced in a particular cell type. Which chromatin modification is most likely responsible?

Accepted Answer

DNA methylation

Question 17

Which of the following best describes the difference between euchromatin and heterochromatin in terms of gene expression?

Accepted Answer

Euchromatin is transcriptionally active, heterochromatin is inactive

Question 18

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

Accepted Answer

Synthesizing ribosomal RNA

Question 19

A cell is observed to have an abnormally high level of heterochromatin. Which of the following is the most likely consequence?

Accepted Answer

Decreased global gene expression

Question 20

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

Accepted Answer

It is the site of ribosomal RNA synthesis and ribosome assembly

Chapter 16: The Structural Basis of Cellular Information – The Nucleus and Chromatin

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