Question 1

Which of the following best describes the primary function of RNA interference (RNAi) in eukaryotic cells?

Accepted Answer

To silence transposons, defend against viruses, and regulate gene expression

Question 2

Which of the following statements about long non-coding RNAs (lncRNAs) is TRUE?

Accepted Answer

lncRNAs are poly-adenylated and not dependent on Dicer for their function

Question 3

In mammals, X-inactivation is a process that ensures dosage compensation between males and females. Which of the following is a key feature of X-inactivation?

Accepted Answer

It results in the formation of a Barr body in female somatic cells

Question 4

A female mammal is heterozygous for an X-linked gene affecting fur color. What is the most likely cellular outcome due to X-inactivation?

Accepted Answer

Each cell randomly inactivates one X chromosome, leading to patches of cells expressing different alleles

Question 5

Which experiment would best demonstrate that Xist acts in cis to inactivate chromosomes?

Accepted Answer

Expressing Xist from an autosome and observing inactivation of that autosome

Question 6

Which of the following best explains why color blindness, an X-linked recessive trait, is less common in females than in males?

Accepted Answer

Heterozygous female carriers express some retina cells with no color photoreceptors due to random X-inactivation

Question 7

Which of the following is NOT a function of small interfering RNAs (siRNAs) or microRNAs (miRNAs)?

Accepted Answer

Directly catalyzing protein synthesis

Question 8

In Drosophila, dosage compensation is achieved by:

Accepted Answer

Doubling the transcription rate of the single X chromosome in males

Question 9

Which of the following statements about the relationship between Xist and Tsix is correct?

Accepted Answer

Xist coats the inactive X chromosome, while Tsix is expressed on the active X chromosome

Question 10

Which of the following best describes the mechanism of X-inactivation in eutherian mammals?

Accepted Answer

It is a random process that occurs in female somatic cells during embryonic development and is stably inherited by daughter cells

Question 11

Which of the following is a characteristic of lncRNAs but NOT of microRNAs?

Accepted Answer

They are usually longer than 200 nucleotides and not translated into protein

Question 12

A researcher creates a Dicer knockout mouse. Which process is most likely to be disrupted?

Accepted Answer

Processing of microRNAs and siRNAs for gene silencing

Question 13

Which of the following best describes the role of roX lncRNA in Drosophila dosage compensation?

Accepted Answer

It recruits the male-specific lethal (msl) complex to the X chromosome in males to upregulate gene expression

Question 14

Which of the following is a direct experimental observation supporting the cis-acting nature of Xist?

Accepted Answer

Driving Xist expression from an autosome leads to inactivation of that autosome

Question 15

Which of the following best explains why X-inactivation is considered 'heritable' within a cell lineage?

Accepted Answer

The inactivated X chromosome is permanently silenced in all descendants of the original cell

Question 16

Which of the following is a key difference between the mechanisms of dosage compensation in mammals and worms?

Accepted Answer

Mammals randomly inactivate one X chromosome in females, while worms repress transcription of both X chromosomes by half in hermaphrodites

Question 17

Which of the following best describes the relationship between non-coding RNAs and the central dogma of molecular biology?

Accepted Answer

Non-coding RNAs regulate gene expression at the RNA level, adding complexity to the central dogma

Question 18

Which of the following is a property shared by both Xist and Tsix lncRNAs?

Accepted Answer

They are both expressed at low levels on both X chromosomes before inactivation

Question 19

A mutation deletes a large portion of the Xist gene in a female mouse. What is the most likely outcome?

Accepted Answer

X-inactivation fails to occur, leading to overexpression of X-linked genes

Non-coding RNAs and Dosage Compensation: Mechanisms and Implications last

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