Transcription and RNA Processing Vocabulary

22 vocabulary flashcards covering transcription basics, RNA types, promoters, processing, and key molecular players.

Messenger RNA (mRNA)

Encodes the amino acid sequences of polypeptides

Ribosomal RNA (rRNA)

Constituent of ribosomes, the molecular machines that synthesize proteins.

Transfer RNA (tRNA)

Reads mRNA codons and delivers the corresponding amino acids to a growing polypeptide chain during protein synthesis.

Noncoding RNA (ncRNA)

RNA molecules with catalytic, structural, or regulatory roles (e.g., miRNA, lncRNA, snRNA).

RNA polymerase

Enzyme that catalyzes transcription. requires a DNA template, pools of ribonucleotide triphosphates (ATP, GTP, etc.) and Mg2+. Adds ribonucleotides to the 3’-OH end, building RNA 5’ to 3’. No proofreading.

Prokaryotic Promoters

The consensus sequence, includes a UP element (AT-rich, -60 to -40), a -35 region (TTGACA), a spacer, and a -10 Pribnow box region (TATAAT), plus an initiation site at +1.

Initiation of transcription

A pre-initiation complex is formed with initiation factor proteins (TATA box + binding protein, transcription factors, and enhancer elements). Then, polymerase is recruited

Elongation

Stage in which the growing RNA chain is extended by addition of ribonucleotides; RNA–DNA hybrid double helix forms briefly.

p-independent termination

Self-complementary region that forms a “hairpin”, which disrupts interactions between RNA and DNA template, releases RNA polymerase

DNA template strand

Serves as a template for RNA synthesis

Nontemplate (coding) strand

DNA strand whose sequence is identical to the transcribed RNA (T in DNA corresponds to U in RNA).

Eukaryotic promoters

Promoter region in eukaryotes that recruits RNA polymerase II; often contains TATA box (core promoter), CAAT box, and GC box (regulatory promoter components).

5′ cap

7-methylguanosine cap, a modified guanosine nucleotide, is added to the 5′ end of eukaryotic mRNA to protect it from degradation, aid in export from the nucleus, and promote translation.

Poly(A) tail

String of adenine nucleotides ~100-250 As long, is added to the 3’ end of eukaryotic mRNA. Protects mRNA from degradation, helps with export to the cytosol, and facilitates translation

Spliceosome

Ribonucleoprotein complex that removes introns and joins exons during mRNA splicing; recognizes GU/AG boundaries.

Eukaryotic RNA Polymerases

Pol I (synthesizes pre-ribosomal RNA); Pol II (mRNA, ncRNA); Pol III (tRNA, 5S rRNA, ncRNA)

p-dependent terminators

In prokaryotes, p (rho) has RNA-DNA helicase activity, which recognizes and binds the rho-utilization site (rut). When p encounters RNA pol, it promotes its release

RNA splicing

mRNA is cut at the 5’ splice site (junction of 5’ exon and intron). The 5’ end of intron is joined to the branch point within the intron, generating a “lasso” shaped molecule. Next, the 3’ splice site is cut and the two exons are joined together while the intron is released.