Each Okazaki fragment starts with a primer sequence of RNA 10 bases long that provides the 3’–OH end for extension by DNA polymerase

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#Id: 6775

#Unit 3. Fundamental Processes

mRNP export from the nucleus into the cytoplasm is controlled by the phosphorylation and dephosphorylation of mRNP adapter proteins, REF, the NXF1/NXT1 mRNP exporter to mRNPs. 

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#Id: 6776

#Unit 3. Fundamental Processes

SR Proteins, in its phosphorylated form, the SR protein initially binds to nascent pre-mRNA. When 3′ cleavage and polyadenylation are completed, the adapter protein is dephosphorylated by a specific nuclear protein phosphatase that is essential for mRNP export. Only the dephosphorylated adapter protein can bind the mRNP exporter, thereby coupling mRNP export to correct polyadenylation.

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#Id: 6777

#Unit 3. Fundamental Processes

Mutation of either the 5′ or the 3′ invariant splice-site bases at the ends of the intron resulted in pre-mRNAs that were bound by snRNPs to form spliceosomes; however, RNA splicing was blocked, and the pre-mRNA was retained in the nucleus. 

In contrast, mutation of both the 5′ and 3′ splice sites in the same pre-mRNA resulted in export of the unspliced pre-mRNA, although less efficiently than for the spliced mRNA, probably because of the absence of an exon-junction complex. When both splice sites were mutated, the pre-mRNAs were not efficiently bound by snRNPs, and consequently, their

export was not blocked.

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#Id: 6778

#Unit 3. Fundamental Processes

The estimate is that as much as 70% of human genes produce antisense RNA.

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#Id: 6779

#Unit 3. Fundamental Processes

Clustered Regularly Interspaced Short Palindromic Repeats CRISPR consist of repeated sequences (each 30 bp long and highly conserved within a given cluster) interleaved with spacer sequences of similar length but highly divergent sequence.

TLS Online TPP Program

#Id: 6780

#Unit 3. Fundamental Processes

The mechanism of spacer sequence acquisition is as 

Each new spacer sequence is inserted next to the leader sequence, with the consequence that the array is a temporal record of acquisitions past. The sequence destined to become spacer is, within the phage genome, known as a “proto-spacer” and lies adjacent to a PAM sequence