MCQs

Post-transcriptional enzymatic modifications generate unique bases in tRNA to stabilize its complex three-dimensional tertiary structure.

The carboxyl group of the amino acid forms a high-energy ester linkage with the 3'-OH group of the terminal adenosine on the tRNA.

Introns are intervening sequences that do not code for proteins and are spliced out before the mRNA leaves the nucleus.

RNA Polymerase II is exclusively responsible for the transcription of all protein-coding structural genes into mRNA in eukaryotes.

Heterogeneous nuclear RNA (or pre-mRNA) represents the raw, unprocessed transcript containing both exons and introns.

The peptidyl transferase center is entirely composed of conserved domains of the large subunit's ribosomal RNA (ribozyme activity).

The eukaryotic 80S ribosome dissociates into a 60S large subunit and a 40S small subunit; the 40S subunit contains the 18S rRNA.

Transfer RNA bridges the gap by binding to a specific mRNA codon on one end while carrying the corresponding amino acid on the other.

The Shine-Dalgarno sequence is a purine-rich region upstream of the start codon that pairs with the 16S rRNA of the prokaryotic ribosome.

The 2' -OH group acts as a nucleophile that can attack the adjacent phosphodiester backbone, making RNA chemically less stable than DNA.

Eukaryotic RNA Polymerase III handles the transcription of smaller, structural non-coding RNAs including tRNA and 5S rRNA.

Alternative splicing allows different combinations of exons to be joined, producing multiple distinct protein isoforms from a single gene.

The prokaryotic 30S small ribosomal subunit contains the 16S rRNA molecule, which plays a key role in identifying the Shine-Dalgarno sequence.

The wobble hypothesis states that non-standard base pairing can occur between the third base of a codon and the first base of an anticodon.

Complementary bases within the single-stranded tRNA bend back and form hydrogen bonds, creating its characteristic shapes.

AUG is the universal start codon that codes for methionine in eukaryotes and formyl-methionine in prokaryotes.

Without a nuclear envelope separating DNA from ribosomes, prokaryotes can simultaneously transcribe and translate a genetic message.

The poly-A tail protects mRNA from 3' exonucleases, extending its operational lifespan within the cytoplasm.

Aminoacyl-tRNA synthetase is the specific enzyme that catalyzes the esterification of a specific amino acid to its cognate tRNA.