The oxoG adduct is highly mutagenic because it can base-pair with adenine as well as with cytosine. If it base-pairs with adenine during replication, it gives rise to a G:C to T:A transversion, which is one of the most common mutations found inhuman cancers.

TLS Online TPP Program

#Id: 6659

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6660

#Unit 3. Fundamental Processes

The sequence AAUAAA is a signal for cleavage to generate a 3’ end of mRNA that is polyadenylated. Addition of poly(A) to nuclear RNA can be prevented by the analog 3’–deoxyadenosine known as cordycepin

TLS Online TPP Program

#Id: 6661

#Unit 3. Fundamental Processes

The site of cleavage/polyadenylation in most pre-mRNAs is flanked by two cis-acting signals:  An upstream AAUAAA motif, which is usually located 11 to 30 nucleotides from the site, and  A downstream U-rich or GU-rich element. 

he AAUAAA is needed for cleavage and polyadenylation because deletion or mutation of the AAUAAA hexamer prevents generation of the polyadenylated 3’ end

TLS Online TPP Program

#Id: 6662

#Unit 3. Fundamental Processes

Ser2 phosphatase Fcp1 regenerates RNA Pol II pool

TLS Online TPP Program

#Id: 6663

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6664

#Unit 3. Fundamental Processes

Splicing is an SN2 reaction that proceeds through a pentavalent phosphorous intermediate.