The 5’–3’ exonuclease activity removes the RNA primer while simultaneously replacing it with a DNA sequence extended from the 3’–OH end of the next Okazaki fragment. 

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#Id: 6136

#Unit 3. Fundamental Processes

XPC detect distortions = UvrA in E. coli

Formation of the bubble involves the helicase activities of the proteins XPA and XPD (the equivalent to UvrB in E. coli) and the single-strand-binding protein RPA. The bubble creates cleavage sites 5’ to the lesion for a nuclease known as ERCC1-XPF and 3’ to the lesion for nuclease XPG (representing the function of UvrC). In higher cells, the resulting DNA strand is 24–32 nucleotides long. As in bacteria, the DNA strand is released to create a gap that is filled in by the action of DNA polymerase and ligase.

XPB and XPD are both helicases; the XPB helicase is required for promoter melting during transcription, while the XPD helicase performs the unwinding function in NER

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#Id: 6755

#Unit 3. Fundamental Processes

Most mRNAs decay stochastically (like the decay of radioactive isotopes), and as a result mRNA stability is usually expressed as a half- life (t½).

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#Id: 4649

#Unit 13. Methods in Biology

bromodeoxyuridine (BrdU) is rapidly phosphorylated and incorporated in its place into newly synthesized DNA hence BrdU is used to detect replicating cells

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#Id: 5574

#Unit 7. System Physiology – Animal

There are four isoforms of the transport protein:  UT-A in the kidneys (UT-A1 to UT-A4) UT-B in the erythrocytes & descending limbs of the vasa recta 

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#Id: 1703

#Unit 4. Cell Communication and Cell Signaling

Neutrophils phagocytose (engulf) bacteria very effectively, and also secrete a range of proteins that have antimicrobial effects and tissue remodeling potential.