Ribonucleic acid (RNA)

Telomerase is a reverse transcriptase that carries its own internal RNA molecule to serve as a structural template for lengthening chromosome ends.

The creation of a cryptic splice site inside an intron leads the spliceosome to misidentify the intron boundaries, incorporating junk sequence into the mature mRNA.

Promoter hypermethylation creates a structural barrier that blocks the binding of transcription factors and RNA polymerase, shutting down transcription.

Converting a CAA codon (coding for glutamine) into a UAA codon introduces a premature stop signal, producing a shorter, tissue-specific protein.

Replacing the 2'-OH group removes the nucleophile required for autophilic attack, making the synthetic RNA highly resistant to ribonuclease degradation.

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

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

The sigma subunit is a transient initiation factor that grants the core prokaryotic RNA polymerase structural specificity to bind promoters.

In basic solutions, the 2'-OH group of ribose is deprotonated, launching a nucleophilic attack on the adjacent phosphorus atom that breaks the RNA backbone.

The ribosome checks only the codon-anticodon match. The 3'-UUG-5' anticodon will pair with a 5'-AAC-3' codon, incorrectly introducing methionine.

Alternative splicing allows exons to be skipped or combined in different ways, creating diverse protein products from one primary transcript.

Without a protective 3' poly-A tail, newly exported cytoplasmic mRNA molecules are quickly targeted and broken down by cellular exonucleases.

The 2'-OH group on the ribose ring structurally prevents the RNA-DNA hybrid from matching the B-form geometry, forcing it into an A-form configuration.

Puromycin structurally mimics an aminoacyl-tRNA, entering the A site and forming a premature peptide link that causes the peptide chain to detach.

The branch-point sequence contains an adenine residue whose 2'-OH attacks the 5' splice site, a critical step for lariat formation during splicing.

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

The AAUAAA consensus sequence is recognized by specific endonucleases that cleave the nascent RNA transcript before poly-A polymerase adds the tail.

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

miRNAs are tiny, non-coding RNA molecules that associate with RISC complexes to pair with matching mRNAs and suppress translation.