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How is RNA modified before it leaves the nucleus?

How is RNA modified before it leaves the nucleus?

Before leaving the nucleus as mRNA, eukaryotic transcripts are modified or processed in several ways. Both exons and introns are transcribed from DNA into RNA. However before the RNA leaves the nucleus the introns are removed and the exons are joined to produce an mRNA molecule with a continuous coding sequence.

What modifications are made to the mRNA prior to leaving the nucleus?

The pre-mRNA has to go through some modifications to become a mature mRNA molecule that can leave the nucleus and be translated. These include splicing, capping, and addition of a poly-A tail, all of which can potentially be regulated – sped up, slowed down, or altered to result in a different product.

How does an RNA molecule get modified?

Immediately after a gene in a eukaryotic cell is transcribed, the new RNA molecule undergoes several modifications known as RNA processing. Then an enzyme called poly-A polymerase adds a chain of adenine nucleotides to the RNA.

How pre-mRNA is changed during RNA processing?

The three most important steps of pre-mRNA processing are the addition of stabilizing and signaling factors at the 5′ and 3′ ends of the molecule, and the removal of intervening sequences that do not specify the appropriate amino acids. In rare cases, the mRNA transcript can be “edited” after it is transcribed.

Which RNA is involved in mRNA processing?

Section 11.2Processing of Eukaryotic mRNA. As discussed in Chapter 4, the initial primary transcript synthesized by RNA polymerase II undergoes several processing steps before a functional mRNA is produced.

What are the three major steps in mRNA processing?

what are the three major steps of mRNA processing? Splicing, adding of the cap and tail, and the exit of the mRNA from the nucleus.

How does RNA processing affect gene expression?

RNA transcription makes an efficient control point because many proteins can be made from a single mRNA molecule. Transcript processing provides an additional level of regulation for eukaryotes, and the presence of a nucleus makes this possible.