Question 1

Which of the following correctly matches the ribosomal RNA components of the large subunit in prokaryotes and eukaryotes?

Accepted Answer

Prokaryotic: 23S + 5S; Eukaryotic: 5.8S + 28S + 5S

Question 2

The Svedberg unit (S) used to measure ribosomal subunit size is based on which property?

Accepted Answer

Size, shape, and conformation state of the subunit

Question 3

Which chemical modification is commonly found in human tRNAs and involves the conversion of uridine to a more stable nucleoside?

Accepted Answer

Conversion of uridine to pseudouridine ($$\Psi)$$

Question 4

During RNA transcription in eukaryotes, which step is unique compared to prokaryotes?

Accepted Answer

RNA processing including splicing, capping, and polyadenylation

Question 5

Which type of small RNA is primarily involved in post-transcriptional gene silencing by guiding the RISC complex to target mRNAs?

Accepted Answer

miRNA

Question 6

What is the primary function of the Argonaute protein in the RNA-induced silencing complex (RISC)?

Accepted Answer

It binds guide RNAs and facilitates cleavage or repression of target mRNAs

Question 7

In the discovery of RNA interference (RNAi), what was the effect of introducing double-stranded RNA (dsRNA) into C. elegans?

Accepted Answer

Silencing of specific gene expression resulting in a phenotype change

Question 8

Which enzyme is responsible for cleaving double-stranded RNA into small fragments during RNA interference?

Accepted Answer

Dicer

Question 9

A researcher wants to knock down the expression of a gene in human cells. Which RNA-based tool would be most effective for this purpose?

Accepted Answer

Small interfering RNA (siRNA)

Question 10

Which of the following is a function of long non-coding RNAs (lncRNAs) in the cell?

Accepted Answer

Regulating chromatin structure and gene expression

Question 11

Xist RNA is crucial for X-chromosome inactivation in mammals. What is its mechanism of action?

Accepted Answer

It spreads along the X chromosome and recruits chromatin-modifying complexes to silence gene expression

Question 12

Which RNA molecule is most abundant in the cell and forms the structural and functional core of ribosomes?

Accepted Answer

rRNA

Question 13

A mutation prevents the methylation of guanine in tRNA. What is the most likely consequence?

Accepted Answer

Reduced tRNA stability and altered folding

Question 14

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

Accepted Answer

They bind to complementary sequences in mRNA to inhibit translation or promote degradation

Question 15

During RNA-seq library preparation, which step ensures that only RNA molecules of a specific size range are sequenced?

Accepted Answer

Size selection

Question 16

Which small RNA is primarily involved in the defense against transposable elements in germ cells?

Accepted Answer

piRNA

Question 17

If a mutation disrupts the function of the Dicer enzyme, which process would be most directly affected?

Accepted Answer

Processing of double-stranded RNA into siRNAs and miRNAs

Question 18

Which equation best represents the central dogma of molecular biology?

Accepted Answer

$$\mathrm{DNA} \rightarrow \mathrm{RNA} \rightarrow \mathrm{Protein}$$

Question 19

Which RNA molecule is directly involved in removing introns from pre-mRNA in eukaryotes?

Accepted Answer

snRNA

Question 20

A scientist isolates a small RNA fragment of about 10 nucleotides from a human cell. Which type of RNA is this most likely to be?

Accepted Answer

tRF (tRNA fragment)

RNA Processing, Regulatory RNAs, and RNA Interference

Study Guide - Practice Questions