MCQs

In historical genetic code experiments, UUU was discovered to be the specific codon that codes for the amino acid phenylalanine.

Small nucleolar RNAs (snoRNAs) reside within the nucleolus and act as guide RNAs that direct the biochemical modification and splicing of pre-rRNA.

The structural domains of rRNA inside the A and P binding sites form precise non-covalent contacts to align the tRNA for peptide synthesis.

Double-stranded RNA is a hallmark of viral replication; eukaryotic cells use the Dicer and RISC pathways to recognize and destroy it.

The D-loop gets its name from containing dihydrouracil and plays a key structural role in recognition by aminoacyl-tRNA synthetase.

The size and weight of an mRNA molecule depend entirely on the length of the specific polypeptide chain it is meant to code for.

Short-lived mRNA allows bacteria to quickly shut down old metabolic pathways and transcribe new genes when conditions change.

RNA synthesis uses nucleoside triphosphates (ATP, CTP, GTP, UTP); the cleavage of pyrophosphate yields the energy needed for polymerization.

Eukaryotic structural genes are organized as split sequences where protein-coding regions (exons) are interrupted by non-coding regions (introns).

The anticodon loop exposes three nucleotide bases designed to form anti-parallel hydrogen bonds with the matching mRNA codon triplet.

Capping enzymes require the 5' triphosphate terminal structure of the nascent RNA transcript to successfully link the inverted guanosine cap.

The P (peptidyl) site retains the tRNA molecule attached to the evolving polypeptide chain before transferring it to the incoming A-site tRNA.

The A (aminoacyl) site welcomes the newly arrived, charged tRNA molecule carrying the next amino acid to be added to the growing peptide chain.

The physical stress of the hairpin combined with the weak hydrogen bonds of the U-rich stretch forces the transcript to detach from the DNA template.

Uncharged tRNAs lack attached amino acids; their buildup indicates that the cell is running low on amino acids to fuel protein translation.

RNA polymerases possess the unique biochemical capacity to initiate the synthesis of a new polynucleotide chain completely de novo.

Double-stranded RNA genomes rely on regular hydrogen bonds between complementary base pairs, specifically adenine-uracil and guanine-cytosine.

The signal recognition particle contains a specific small cytoplasmic RNA molecule known as 7SL RNA, which guides newly synthesizing proteins to the ER.

Specific identity elements scattered across the acceptor stem and variable loops allow the synthetase to accurately identify its matching tRNA.