L16 RNA Processing

What is RNA processing?

It refers to chemical modifications of the primary RNA transcript to produce functional RNA molecules.

What are the main steps in mRNA processing?

5′ capping, 3′ polyadenylation, intron removal (splicing), and sometimes RNA editing.

What is the function of the 5′ cap in mRNA?

It protects from nuclease degradation, aids in transport to the cytoplasm, and helps ribosome recognition.

Which enzyme adds the poly-A tail?

Poly A polymerase.

What is the GU-AG rule?

Most introns begin with GU and end with AG; these sequences help spliceosome recognize intron boundaries.

What are snRNPs?

Small nuclear ribonucleoproteins involved in intron removal during RNA splicing.

What is a ribozyme?

An RNA molecule capable of catalyzing its own splicing without proteins.

What is alternative splicing?

A mechanism that allows different mRNAs (and proteins) to be produced from the same gene.

Name one biological example where alternative splicing is crucial.

Sex determination in Drosophila.

What is RNA editing?

Post-transcriptional modifications that alter nucleotide sequences in mRNA.

What are the two main types of RNA editing?

Base addition/deletion and base conversion.

How are tRNAs processed?

Cleavage, intron removal, 3′ end modification, and base modifications.

How is rRNA processed?

Transcription as a long precursor, methylation, cleavage, and trimming into mature rRNAs.

Why do eukaryotic genes contain introns?

They enable alternative splicing, exon shuffling, and may give rise to miRNAs.

What are guide RNAs (gRNAs)?

RNAs that guide insertion or deletion of uridines during RNA editing in organisms like trypanosomes.