TLS Online TPP Program

#Id: 5927

#Unit 3. Fundamental Processes

In E. coli, two clusters of five ter sites each, including terK, -I, -E, -D, and -A on one side and terC, -B, -F, -G, and -H on the other, are located 100 kb on either side of this termination region.

Each set of ter sites is specific for one direction of fork movement

TLS Online TPP Program

#Id: 5991

#Unit 3. Fundamental Processes

Eukaryotic replication is similar in most aspects to bacterial replication. It is semiconservative, bidirectional, and semidiscontinuous.

TLS Online TPP Program

#Id: 5992

#Unit 3. Fundamental Processes

Eukaryotic replicons are 40 to 100 kb in length and individual replicons are activated at characteristic times during S phase.

TLS Online TPP Program

#Id: 5993

#Unit 3. Fundamental Processes

Replicons in euchromatin initiate before replicons in heterochromatin

TLS Online TPP Program

#Id: 5994

#Unit 3. Fundamental Processes

The rate of replication is 2000 bp/min, which is much slower than the 50,000 bp/min of bacterial replication fork movement, presumably because the chromosome is assembled into chromatin, not naked DNA.

TLS Online TPP Program

#Id: 5995

#Unit 3. Fundamental Processes

From the speed of replication, it is evident that a mammalian genome could be replicated in 1 hour if all replicons functioned simultaneously. S phase actually lasts for 6 hours in a typical somatic cell, though, which implies that no more than 15% of the replicons are likely to be active at any given moment.