In response to the molecular cues received during cell division, these molecules initiate DNA replication, and synthesize two new strands using the existing strands as templates.
Hence the process of DNA replication is said to be a semi-conservative one.
The series of events that occur during prokaryotic DNA replication have been explained below.
Leading and lagging strands: Leading strand is the one in which the direction of DNA chain elongation and overall fork movement is the same and lagging strand is the one in which they are opposite.
How can an antiparallel DNA () strand be duplicated by a that synthesises DNA in only one direction? This paradox of DNA synthesis on the lagging strand was dissolved by discovery of Okazaki fragments. The major components of the bacterial replication fork include , and . The loading of , , is the most critical step for assembly of a primosome, a protein complex responsible for duplex unwinding and primer RNA () synthesis at the replication fork. may be an asymmetric dimer, each of which may concurrently synthesise leading or lagging strand. Several different modes of primosome assembly have been identified in bacteria. At oriC (origin of chromosome), -dependent primosome is assembled for initiation of a round of DNA replication, whereas -dependent primosome is assembled at stalled replication forks to facilitate replication restart.
On the other hand, eukaryotic DNA replication is intricately controlled by the cell cycle regulators, and the process takes place during the 'S' or synthesis phase of the cell cycle.
This Concept Map, created with IHMC CmapTools, has information related to: dna replication, an RNA primer which is replaced by DNA polymerase I, synthesized continuously by DNA polymerase, enzymes and proteins such as DNA ligase, DNA polymerase I then the Okazaki fragments are linked covalently, the Okazaki fragments are linked covalently by DNA ligase, semiconservative meaning one strand is conserved, enzymes and proteins such as gyrase, DNA helicase unzips DNA helix, discontinuously synthesized first RNA primase, gyrase produce breaks in DNA to prevent knotting and strain, enzymes and proteins such as DNA helicase, enzymes and proteins such as DNA polymerase I, DNA helix forming replication fork, enzymes and proteins such as RNA primase, free nucleotides in 5' -> 3' direction, DNA Replication is semiconservative, enzymes and proteins such as DNA polymerase III, replication fork forms leading strand, single stranded binding proteins keep DNA separated, lagging strand is discontinuously synthesized
This is known as the leading strand.
Here, DNA polymerase III (DNA pol III) recognizes the 3' OH end of the RNA primer, and adds new complementary nucleotides.
This strand is known as the lagging strand since the process of DNA synthesis on this strand proceeds at a lower rate.
Here, the primase adds primers at several places along the unwound strand.