RNAtranskriptien

RNA transcripts are RNA molecules synthesized from a DNA template during transcription. They are the primary products of gene expression and can serve as templates for protein synthesis or as functional RNA in the cell. Transcription is carried out by RNA polymerases, which add nucleotides according to the DNA sequence.

In bacteria, a single RNA polymerase transcribes most genes and terminates at specific signals. In eukaryotes, three RNA polymerases carry out distinct tasks: RNA polymerase I synthesizes most ribosomal RNA, RNA polymerase II transcribes messenger RNA and many non-coding RNAs, and RNA polymerase III makes transfer RNA and other small RNAs. The RNA polymerase II transcripts often require processing to become mature RNAs.

Most eukaryotic transcripts are produced as primary transcripts that undergo processing. Messenger RNAs receive a 5' cap and a 3' poly(A) tail and may be spliced to remove introns. Non-coding transcripts such as microRNAs or small interfering RNAs are produced from longer precursors and processed into functional forms. Ribonucleic transcripts such as rRNA and tRNA also mature through processing and modification. Transcript roles vary: mRNA carries genetic information for protein synthesis, rRNA and tRNA form the core machinery of the ribosome, and small RNAs regulate gene expression and RNA stability. Transcription is regulated by promoters, enhancers, transcription factors, and chromatin state, while RNA stability and decay pathways shape cellular RNA levels. RNA transcripts thus link the genome to the proteome and underpin many research and biotechnological applications.