Question 1

Which of the following best describes the function of microRNAs (miRNAs) in gene expression regulation?

Accepted Answer

miRNAs bind to mRNA and either degrade the mRNA or block its translation.

Question 2

A mutation disables the gene for a miRNA that normally degrades mRNA coding for a protein promoting cell division. What is the most likely outcome?

Accepted Answer

Cell division will increase due to accumulation of the protein.

Question 3

Which equation best represents the proportion of the human genome that is protein-coding DNA?

Accepted Answer

$$\frac{1.5}{100}$$

Question 4

What is the primary difference between miRNAs and siRNAs?

Accepted Answer

miRNAs and siRNAs differ mainly in the structure of their RNA precursors.

Question 5

Which process is referred to as RNA interference (RNAi)?

Accepted Answer

The blocking of gene expression by siRNAs.

Question 6

In yeast, siRNAs are required for which chromatin-related process during the cell cycle?

Accepted Answer

Formation of heterochromatin at centromeres.

Question 7

piwi-associated RNAs (piRNAs) play a crucial role in which of the following?

Accepted Answer

Blocking expression of transposons and reestablishing methylation patterns in germ cells.

Question 8

Which of the following statements about noncoding RNAs is FALSE?

Accepted Answer

Noncoding RNAs are only found in multicellular eukaryotes.

Question 9

If an miRNA and its target mRNA are perfectly complementary, what is the most likely outcome?

Accepted Answer

The mRNA will be degraded.

Question 10

Which of the following best explains why the RNAi pathway may have evolved?

Accepted Answer

As a natural defense against infection by viruses with double-stranded RNA genomes.

Question 11

Which of the following is a plausible consequence of disabling the gene for an miRNA that targets a tumor suppressor mRNA?

Accepted Answer

Increased translation of the tumor suppressor protein, potentially reducing cancer risk.

Question 12

Which of the following best describes the role of the CRISPR-Cas9 system in bacteria?

Accepted Answer

It uses small noncoding RNAs to defend against viral infection.

Question 13

Which of the following is NOT a function of small noncoding RNAs?

Accepted Answer

Directly catalyzing protein synthesis.

Question 14

Which formula best represents the estimated number of miRNA genes in the human genome?

Accepted Answer

$$\approx 1,500$$

Question 15

Which scenario best illustrates the use of RNA interference (RNAi) in laboratory research?

Accepted Answer

Injecting siRNA precursor molecules to disable specific genes and study their function.

Question 16

Which of the following is TRUE regarding piRNAs?

Accepted Answer

piRNAs are processed from a longer, single-stranded RNA precursor and are usually 24–31 nucleotides in length.

Question 17

Which of the following best describes the relationship between miRNAs and the regulation of human genes?

Accepted Answer

miRNAs regulate the expression of at least half of all human genes.

Question 18

Which of the following is a real-world application of noncoding RNAs in medicine or biotechnology?

Accepted Answer

Using siRNAs to silence disease-causing genes in gene therapy.

Question 19

Which of the following best explains the mechanism by which miRNAs block translation?

Accepted Answer

miRNAs form a complex with proteins that binds to mRNA, preventing ribosome attachment.

Question 20

Which of the following best describes the role of noncoding RNAs in chromatin remodeling?

Accepted Answer

Noncoding RNAs interact with chromatin-modifying enzymes to condense chromatin into heterochromatin.

Noncoding RNAs and Their Roles in Gene Expression Regulation

Study Guide - Practice Questions