Question 1

Which of the following best describes a key structural difference between DNA and RNA?

Accepted Answer

DNA contains thymine, while RNA contains uracil.

Question 2

During the processing of eukaryotic pre-mRNA, which modification is added to the 5' end, and what is its function?

Accepted Answer

A 7-methylguanosine cap is added to facilitate ribosome binding.

Question 3

Which of the following equations correctly represents the formation of the 5' cap on mRNA?

Accepted Answer

$$\mathrm{m^7$GpppN}$$

Question 4

Alternative splicing allows a single gene to:

Accepted Answer

Generate multiple mRNA variants, leading to different polypeptides.

Question 5

Which of the following statements about ribosomal RNA (rRNA) is correct?

Accepted Answer

rRNA forms the catalytic core of ribosomes and is essential for protein synthesis.

Question 6

What is the function of the poly(A) tail added to the 3' end of eukaryotic mRNA?

Accepted Answer

It increases mRNA stability and facilitates ribosome binding.

Question 7

Which of the following best describes the role of small nuclear RNA (snRNA) in eukaryotic cells?

Accepted Answer

snRNA is involved in the splicing of pre-mRNA by forming part of the spliceosome.

Question 8

Which of the following is a distinguishing feature of siRNA compared to miRNA?

Accepted Answer

siRNA is derived from double-stranded RNA of exogenous origin, while miRNA is transcribed from endogenous genes.

Question 9

A mutation in the branch point sequence of an intron would most likely affect which process?

Accepted Answer

Splicing of pre-mRNA

Question 10

Which of the following best describes the function of CRISPR RNA (crRNA) in prokaryotes?

Accepted Answer

crRNA guides the effector complex to foreign DNA for cleavage and defense.

Question 11

Which of the following steps is NOT involved in the processing of tRNA?

Accepted Answer

Addition of a 5' cap

Question 12

Which equation best represents the base-pairing interaction between an anticodon of tRNA and a codon of mRNA?

Accepted Answer

$$\mathrm{Anticodon\ (3'\rightarrow5')\ \equiv\ Codon\ (5'\rightarrow3')}$$

Question 13

Which of the following is a function of long non-coding RNA (lncRNA) in eukaryotic cells?

Accepted Answer

lncRNA controls gene expression by interacting with proteins, chromatin, or mRNA.

Question 14

A researcher observes that a certain RNA molecule is about 22 nucleotides long, forms a complex with proteins, and leads to the degradation of viral mRNA. This RNA is most likely:

Accepted Answer

siRNA

Question 15

Which of the following best explains why transcription cannot occur in heterochromatin?

Accepted Answer

Heterochromatin is highly condensed, preventing access of RNA polymerase to DNA.

Question 16

Which of the following is true regarding the processing of rRNA in eukaryotes?

Accepted Answer

rRNA is transcribed as a precursor and processed by snoRNPs.

Question 17

Which of the following best describes the function of small nucleolar RNA (snoRNA)?

Accepted Answer

snoRNA modifies rRNA and tRNA and is involved in mRNA editing.

Question 18

A mutation that prevents the formation of the spliceosome would most directly affect which process?

Accepted Answer

Removal of introns from pre-mRNA

Question 19

Which of the following best describes the action of the RNA-induced silencing complex (RISC) containing miRNA?

Accepted Answer

It binds to mRNA by imperfect base pairing and inhibits translation.

RNA Molecules: Structure, Types, and Functions

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