RNA Structure, Function, and Non-coding RNAs

Vocabulary flashcards covering key terms on RNA structure, types, non-coding RNAs, RNA polymerases, gene regulation, and clinical applications.

RNA

Single-stranded polymer of ribonucleotides that carries out gene expression and many regulatory roles.

Ribose

Pentose sugar in RNA that bears a 2′-hydroxyl group, making RNA less chemically stable than DNA.

Uracil

RNA-specific pyrimidine base that replaces thymine and pairs with adenine.

A-form helix

Right-handed helical geometry favored by RNA because of the 2′-OH on ribose.

Messenger RNA (mRNA)

Coding RNA that conveys genetic information from DNA to ribosomes for protein synthesis.

Transfer RNA (tRNA)

Adaptor ncRNA (~70–90 nt) that delivers specific amino acids to the ribosome via its anticodon.

Ribosomal RNA (rRNA)

Catalytic and structural ncRNA forming ribosomes and catalyzing peptide-bond formation.

Coding RNA

RNA species (primarily mRNA) that are translated into proteins.

Non-coding RNA (ncRNA)

RNAs that function without being translated, including tRNA, rRNA, miRNA, lncRNA, etc.

MicroRNA (miRNA)

~22-nt ncRNA that binds 3′UTRs of target mRNAs to inhibit translation or promote degradation.

Small interfering RNA (siRNA)

Exogenous or endogenous ~21-24-nt duplex RNA that directs sequence-specific mRNA cleavage.

PIWI-interacting RNA (piRNA)

26–31-nt ncRNA that partners with PIWI proteins to protect the germ-line genome from transposons.

Small nuclear RNA (snRNA)

Spliceosome component that helps remove introns from pre-mRNA.

Small nucleolar RNA (snoRNA)

Guides chemical modifications (methylation, pseudouridylation) of rRNA and other RNAs.

Long non-coding RNA (lncRNA)

ncRNA >200 nt that regulates gene expression, chromatin structure, and transcription (e.g., Xist).

RNA Polymerase I

Nucleolar enzyme that transcribes 45S precursor rRNA (18S, 5.8S, 28S).

RNA Polymerase II

Nucleoplasmic enzyme that synthesizes pre-mRNA and many snRNA, snoRNA, miRNA transcripts.

RNA Polymerase III

Nucleoplasmic enzyme that produces tRNA, 5S rRNA, and some small RNAs.

TATA box

AT-rich promoter element ~25–30 bp upstream of transcription start site recognized by Pol II machinery.

5′ Cap

7-methylguanosine added co-transcriptionally to mRNA, protecting it from exonucleases and aiding ribosome binding.

Poly-A tail

~200-adenine stretch at the 3′ end of eukaryotic mRNA that enhances stability and nuclear export.

Spliceosome

snRNP complex that removes introns from pre-mRNA during splicing.

Alternative splicing

Process in which different exon combinations produce multiple mRNA isoforms from one gene.

Anticodon

tRNA triplet sequence that base-pairs with the complementary mRNA codon.

CCA 3′ End

Conserved terminal sequence of tRNA where the cognate amino acid is attached.

Dihydrouridine

Modified nucleotide commonly found in the D-arm of tRNA, contributing to structure.

Peptidyl transferase

Ribosomal rRNA catalytic activity that forms peptide bonds during translation.

Ribozyme

Catalytically active RNA molecule, exemplified by rRNA and RNase P.

45S rRNA precursor

Primary Pol I transcript cleaved to generate 18S, 5.8S, and 28S rRNAs.

Ribosomopathy

Disease caused by defective ribosome biogenesis or function (e.g., Diamond-Blackfan anemia).

Diamond-Blackfan anemia

Congenital ribosomopathy characterized by red-cell aplasia due to mutations in ribosomal protein genes.

Mitochondrial tRNA mutations

Genetic changes in mt-tRNA genes leading to disorders such as MELAS and MERRF.

60S ribosomal subunit

Large eukaryotic ribosomal subunit containing 28S, 5.8S, and 5S rRNAs.

40S ribosomal subunit

Small eukaryotic ribosomal subunit that contains 18S rRNA.

RNA-induced silencing complex (RISC)

Protein–RNA complex that uses miRNA or siRNA to guide gene silencing.

Antisense oligonucleotide (ASO)

Synthetic 15–21-nt single-stranded DNA/RNA that binds complementary RNA to modulate its function.

mRNA vaccine

Therapeutic that delivers synthetic mRNA encoding an antigen (e.g., SARS-CoV-2 spike) to elicit immunity.

Tetracycline

Antibiotic that inhibits bacterial translation by blocking tRNA binding to the ribosomal A site.

Macrolide antibiotics

Drug class (e.g., erythromycin) that binds 23S rRNA, preventing peptide-exit tunnel function.

siRNA therapeutic

Double-stranded siRNA drug (e.g., Patisiran) that harnesses RNAi to silence disease genes.

Small nuclear ribonucleoprotein (snRNP)

Complex of snRNA and proteins forming the core of spliceosomes ("snurps").

RNA-based cancer vaccine

mRNA formulation encoding tumor antigens to stimulate T-cell-mediated anti-tumor immunity.

Gene silencing

Down-regulation of gene expression by mechanisms such as miRNA, siRNA, or ASOs.

Nusinersen

ASO drug that modifies SMN2 splicing to treat spinal muscular atrophy.

Eteplirsen

Exon-skipping ASO used in the therapy of Duchenne muscular dystrophy.