Mitochondrial DNA replicates by increasing the number of genomes in proportion to mitochondrial mass, but without ensuring that each genome replicates

the same number of times.

TLS Online TPP Program

#Id: 3039

#Unit 3. Fundamental Processes

The length of the priming RNA is limited to eight to 14 bases. Apparently, DNA polymerase III is responsible for displacing the primase.

TLS Online TPP Program

#Id: 3040

#Unit 3. Fundamental Processes

DNA ligase makes the bond that connects the 3 ' end of one Okazaki fragment to the 5 ' beginning of the next fragment.

TLS Online TPP Program

#Id: 3041

#Unit 3. Fundamental Processes

Synthesis of an Okazaki fragment terminates just before the start of the RNA primer of the preceding fragment.

TLS Online TPP Program

#Id: 3042

#Unit 3. Fundamental Processes

FENl is an exo-jendonuclease that recognizes the structure created when one strand of DNA is displaced from a duplex as a "flap." In mammalian replication it cleaves at the base of the flap to remove the RNA primer.

TLS Online TPP Program

#Id: 3043

#Unit 3. Fundamental Processes

The gap is filled by DNA polymerase I; pol A mutants fail to join their Okazaki fragments properly. 

TLS Online TPP Program

#Id: 3044

#Unit 3. Fundamental Processes

In mammalian systems (where the DNA polymerase does not have a 5'- 3' exonuclease

activity), Okazaki fragments are connected by a two-step process. Synthesis of an Okazaki fragment displaces the RNA primer of the preceding fragment in the form of a "flap’’.

The base of the flap is cleaved by the enzyme FEN1 (flap endonuclease 1 ) .