![]() An RNA primer is therefore generated with the help of RNA primase enzyme, to initiate placing RNA bases complementary to the template strand bases. ĭNA polymerase then starts synthesizing the new strand from 5’ to 3’ direction, but requires a short RNA sequence, approximately 10 nucleotides in length, as a primer to begin the process. Unwinding creates a replication fork that has a leading and a lagging strand, a result of the anti-parallel nature of the strands. Since these bases have only two hydrogen bonds, instead of three, it is an ideal place for the helicase to start unwinding the DNA. The unwinding process is accomplished by DNA helicase that often starts disconnecting the DNA in a region that is rich in adenine (A) and thymine (T). For the replication process to begin, the DNA helix must first unwind by removing the hydrogen bonds holding the two strands together. Each strand is made up of nucleotides joined together by phosphodiester linkages. In eukaryotes, Polymerases δ and ε are the major replicative enzymes.ĭNA has a double helical structure, where the two strands are joined together with hydrogen bonds between the complementary base pairs. The process of replication is a highly complex process and requires a concerted effort of many different proteins including but not limited to DNA Polymerases, Primase, Helicase, and DNA ligase. The newly synthesized RNA molecule then exits the nucleus and enters the cytoplasm, where it is translated into protein. This synthesis is carried out by an enzyme known as RNA polymerase. Transcription is the process where a specific segment of DNA is used as a template and copied into an RNA molecule. Eukaryotic cells, on the other hand, have a linear structure that is organized into tight chromosomes around histones. The prokaryotic DNA is circular and therefore has only one point of origin where replication starts and moves in a bidirectional manner. The difference in eukaryotic replication lies in the larger amount of DNA that is associated with histones. Replication in prokaryotic and eukaryotic cells is quite similar. Replication is known to be semiconservative as the original DNA (the parent strand) splits to make a new strand, while retaining the parent strand. The process is highly regulated and requires many different enzymes that include DNA polymerase, primase, ligase, helicase, and topoisomerase. ![]() Synthesis of histones and other DNA associated proteins is markedly increased in the S-phase. Replication occurs in the S-phase cell and new genetic material is synthesized as a preparation for the cell division. ![]() During the G1 phase, cells grow and produce material like nucleotide precursors as preparation for DNA replication in the S-phase. ![]() The cell cycle consists of four phases-G1, S, G2, and M. The process of replication allows cells to generate new genetic material (DNA) using original DNA as a template. This explains how the genetic information in the form of DNA in a cell is converted to RNA and then to protein for effective utilization. The flow of genetic information in biological systems from DNA>RNA>Protein is the central dogma in molecular biology. ![]()
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