11/9/2023 0 Comments Average okazaki fragment length![]() The strand is synthesized in short segments, named Okazaki fragments, after their discoverer ( Sakabe and Okazaki 1966 Okazaki et al. This can only be accomplished if the strand is made discontinuously ( Kornberg and Baker 1992). The other, or lagging strand, must be periodically extended away from the opening helix. One copied strand, called leading, can conveniently be extended in a continuous manner in the same direction that the helix must open to allow exposure of templates for polymerization. The antiparallel structure of double-helical DNA and the 3′ end extension specificity of all DNA polymerases confine the mechanisms that can be used by the cell for DNA duplication. Replication of cellular chromosomal DNA is initiated by the multienzyme replisome machinery, which unwinds the DNA helix to create a replication fork. The eukaryotic maturation mechanism involves many enzymes, possibly three pathways, and regulation that can shift from high efficiency to high fidelity. The prokaryotic joining mechanism is simple and efficient. Although the prokaryotic fragments are ∼1200 nucleotides long, the eukaryotic fragments are much shorter, with lengths determined by nucleosome periodicity. In both prokaryotes and eukaryotes the lagging-strand fragments are initiated by RNA primers, which are removed by a joining mechanism involving strand displacement of the primer into a flap, flap removal, and then ligation. Genetic analyses and reconstitution experiments identified proteins and multiple pathways responsible for maturation of the lagging strand. The lagging strand needs to be processed to form a functional DNA segment. The leading strand is elongated continuously in the direction of fork opening, whereas the lagging strand is made discontinuously in the opposite direction. Cellular DNA replication requires efficient copying of the double-stranded chromosomal DNA. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |