Polyadenylation requires a protein complex that contains a specificity factor, an endonuclease, and poly(A) polymerase.

 

TLS Online TPP Program

#Id: 2334

#Unit 3. Fundamental Processes

The E. coli rrn  promoters are also regulated by a pair of small molecules: the initiating NTP (the iNTP) and an alarmone,  guanosine 5 -diphosphate 3-diphosphate (ppGpp). 

1. An abundance of iNTP indicates that the concentration of  nucleotides is high, and therefore it is appropriate to synthesize plenty of rRNA. 

2. Accordingly, iNTP stabilizes the open promoter complex, stimulating transcription. 

3. On the other hand, when cells are starved for amino acids, protein synthesis cannot occur readily and the need for ribosomes (and rRNA) decreases. 

TLS Online TPP Program

#Id: 5332

#Unit 7. System Physiology – Animal

Rapid Ventricular Filling

aortic pressure decreases as blood runs off from the aorta into the arterial tree, to the veins, and then back to the heart.

TLS Online TPP Program

#Id: 9585

#Unit 11. Evolution and Behavior

Cretaceous - Diversity of angiosperms and Mass extinctions of marine and terrestrial life, including last dinosaurs

TLS Online TPP Program

#Id: 9190

#Unit 11. Evolution and Behavior

Artificial selection- Genetically improving animals and plants by breeding together the best individuals in their fields and flocks.

TLS Online TPP Program

#Id: 723

#Unit 3. Fundamental Processes

The bacterial DnaA protein is the replication initiator; it binds sequence specifically to multiple sites (dnaA boxes) in oriC.