mRNA Processing Part 1

Eukaryotic mRNA processing involves capping, splicing of exons, and polyadenylation at the 3' end.

The 5' cap stabilizes the mRNA transcript and promotes efficient translation.

The poly-A tail stabilizes the mRNA transcript and facilitates its translation.

<p>Prokaryotic mRNA does not undergo additional processing, as it is transcribed in a 'ready to read' state.</p> Signup and view all the answers

<p>Splicing is crucial for removing introns and linking exons, ensuring that the coding sequence is continuous.</p> Signup and view all the answers

<p>Ribonucleases degrade RNA from the 5' or 3' ends and can also target internal sequences, affecting mRNA stability.</p> Signup and view all the answers

<p>The order is: capping, splicing (during transcription), termination/polyadenylation, and splicing (after termination).</p> Signup and view all the answers

<p>mRNA is inherently unstable due to its ribose sugar structure, which makes it more prone to breakage.</p> Signup and view all the answers

<p>Yeast methylates the position 7 of the GTP, known as 7-m-G-cap.</p> Signup and view all the answers

<p>Vertebrates also methylate the 2 carbon of the +2 nucleotide, known as cap-2.</p> Signup and view all the answers

<p>The cap-binding complex stabilizes mRNA and recruits the spliceosome.</p> Signup and view all the answers

<p>Capping prevents viral RNA from being recognized as self, which triggers an innate interferon response.</p> Signup and view all the answers

<p>The 3' Poly–A-tail is involved in the stability and eventual termination of transcription in eukaryotes.</p> Signup and view all the answers

<p>The Rho-dependent mechanism pulls the mRNA from RNA polymerase.</p> Signup and view all the answers

<p>The mRNA is cleaved from the transcript.</p> Signup and view all the answers

<p>Xrn2 travels along the RNA, degrading it until it reaches RNA polymerase II, causing dissociation.</p> Signup and view all the answers

<p>CstF and CPSF are involved in transcription termination and polya-denylation of the 3' end of mRNA.</p> Signup and view all the answers

<p>The poly(A) signal recruits proteins for mRNA tailing, and the poly(A) site marks where adenylation begins.</p> Signup and view all the answers

<p>It prevents early termination in the event of mutations near the poly(A) site or signal.</p> Signup and view all the answers

<p>CPSF binds to the AAUAAA poly-A signal.</p> Signup and view all the answers

<p>PAP adds adenine residues to the 3' end of mRNA without needing a template.</p> Signup and view all the answers

<p>RNA degradation occurs gradually over time, leading to decreased levels of pre-mRNA and mature RNA.</p> Signup and view all the answers

<p>Instantaneous inhibition causes pre-mRNA levels to drop quickly as they are processed into mature RNA.</p> Signup and view all the answers

<p>Increased mRNA stability allows one transcript to yield more rounds of translated proteins.</p> Signup and view all the answers

<p>E. coli mRNAs are degraded in about 3-5 minutes, while H. sapiens mRNA can last over 10 hours.</p> Signup and view all the answers

<p>The 5' cap protects mRNA from degradation by exonucleases and aids in translation.</p> Signup and view all the answers

<p>Capping enzymes are recruited when the transcript is about 20-30 bases long.</p> Signup and view all the answers

<p>The inverted guanine is methylated at position 7 by guanine-7-methyl transferase.</p> Signup and view all the answers

<p>RNA is unstable due to the presence of an extra -OH group in its ribose sugar.</p> Signup and view all the answers

<p>A 5' to 5' bond is formed between the inverted GTP and the 5' end of the growing mRNA.</p> Signup and view all the answers

<p>Methyl transferase can methylate the 2' -OH of the first two nucleotides.</p> Signup and view all the answers

<p>PAP adds adenine nucleotides to the 3’ end of the mRNA after it is cleaved, and its activity requires binding of poly-A binding protein (PAB).</p> Signup and view all the answers

<p>Having a cap and tail significantly extends the half-life of mRNA, allowing it to persist longer in the cell.</p> Signup and view all the answers

<p>Modified mRNA with caps and tails is more stable, translating faster than unmodified forms due to enhanced protection against degradation.</p> Signup and view all the answers

<p>The absence of either a cap or tail leads to a significant reduction in translation efficiency, with translation becoming notably cap-dependent.</p> Signup and view all the answers

<p>The 5’ cap interacts with eukaryotic intrinsic factors, which associate with the 3’ poly-A tail via PABP, forming a closed-loop structure.</p> Signup and view all the answers

<p>Excess caps or tails destabilize the mRNA by blocking the recycling of ribosomes, thus reducing the efficiency of translation.</p> Signup and view all the answers

<p>PAB is crucial as it binds to the added adenine residues, stimulating further polyadenylation by PAP.</p> Signup and view all the answers

<p>Cleavage of pre-mRNA occurs about 35 bases past the AAUAAA signal, which initiates the polyadenylation process.</p> Signup and view all the answers

Extensive modifications of pre-mRNA to create a mature mRNA in the nucleus, including capping, splicing, polyadenylation, and export to the cytoplasm.

The initial RNA transcript in eukaryotes, still containing introns and needing modifications before it can be functional.

Structures added to the ends of the mRNA molecule that stabilize the mRNA and enhance translation efficiency.

Removing introns (non-coding regions) and joining exons (coding regions) of pre-mRNA

Untranslated regions at the 5' and 3' ends of mRNA that are not translated into protein but play essential roles in gene regulation and mRNA stability.

Control of the lifespan of mRNA molecules, determined by the sequence and structure of the molecule and the presence of cellular factors that can promote or inhibit mRNA degradation.

1. Capping, 2. Splicing (during transcription), 3. Polyadenylation, 4. Splicing (after termination)

RNAs, including mRNA, are naturally unstable due to the presence of reactive functional groups in the ribose sugar molecules.

RNA is broken down and recycled by the cell.

Stopping the process of creating RNA from DNA.

mRNA molecules in E. coli are degraded quickly, about 3-5 minutes.

mRNA molecules in S. cerevisiae last a bit longer, about 20-30 minutes.

mRNA molecules in humans last much longer, over 10 hours.

Adding a cap to the 5' end of pre-mRNA to protect it from degradation.

Capping occurs after a certain length of the pre-mRNA sequence has been made.

Capping involves multiple steps: a GTP addition, methylation of the 7th position, and methylation of the initial two ribose sugars.

Different organisms have varying methylation patterns on the 5' end of mRNA.

A complex of proteins that binds to the mRNA 5' cap, facilitating various mRNA processing steps and transport.

The 5' cap plays a vital role in mRNA processing and stability, initiating translation efficiency, and enabling RNA transport.

The process of adding a poly(A) tail (a string of adenine nucleotides) to the 3' end of mRNA, crucial for mRNA stability and translation initiation.

Vertebrates methylate the 2' carbon of the +1, +2 nucleotides, distinguishing their mRNA from viral mRNA and triggering an innate immune response.

Adding a poly-A tail (a string of adenine nucleotides) to the 3' end of mRNA.

Enzyme that adds the poly-A tail to the 3' end of mRNA.

Protein that binds to the poly-A tail, stimulating further polyadenylation and stabilizing mRNA.

The 5' cap and 3' poly-A tail, crucial for mRNA stability and translation efficiency.

The speed at which ribosomes translate mRNA into proteins.

The process of mRNA leaving the nucleus to enter the cytoplasm (where translation occurs).

A modified guanine nucleotide added to the 5' end of mRNA; essential for efficient translation.

Eukaryotic mRNA is cleaved from the transcript, and the polymerase continues transcribing until an exonuclease degrades the remaining RNA, causing polymerase dissociation.

A DNA sequence that recruits proteins for mRNA tailing and specifies the adenylation start site.

Cleavage stimulation factor, a protein involved in transcription termination and polyadenylation, activated by Ser-2-P.

Cleavage and polyadenylation specificity factor, a protein involved in transcription termination and polyadenylation, activated by Ser-2-P.

A specific sequence in pre-mRNA recognized by CPSF, initiating polyadenylation.

A mechanism of eukaryotic transcription termination where an exonuclease degrades the RNA from the 5' end, causing the polymerase to dissociate.

A 5' → 3' exonuclease that degrades the remaining RNA during termination, triggering polymerase dissociation.

The C-terminal domain of RNA polymerase II; it contains phosphorylation sites that regulate termination.