In mtDNA, The existence of D loops exposes a general principle: An origin can be a sequence of DNA that serves to initiate DNA synthesis using om strand as a Template.

TLS Online TPP Program

#Id: 745

#Unit 3. Fundamental Processes

Additional free energy for the formation of phosphodiester bond is provided by the rapid hydrolysis of the pyrophosphate into two phosphate groups by an enzyme known as pyrophosphatase:

 

TLS Online TPP Program

#Id: 746

#Unit 3. Fundamental Processes

Hydrolysis of pyrophosphate makes phosphodiester bond a highly favorable reaction with a DG of –7 kcal/mol, which corresponds to an equilibrium constant (Keq) of 105.

TLS Online TPP Program

#Id: 747

#Unit 3. Fundamental Processes

A:T and G:C base pairs have same geometry that’s why DNA polymerase has only one catalytic site for polymerization 

TLS Online TPP Program

#Id: 748

#Unit 3. Fundamental Processes

Incorrect base pairing leads to dramatically lower rates of nucleotide addition called as kinetic proofreading

TLS Online TPP Program

#Id: 749

#Unit 3. Fundamental Processes

A common method to monitor synthesis of new DNA is Incorporation Assays.

TLS Online TPP Program

#Id: 750

#Unit 3. Fundamental Processes

rNTPs are present at approximately 10-fold higher concentration in the cell, they are incorporated at a rate that is more than 1000-fold lower than dNTPs.