11/24/2023 0 Comments Dna ligase and okazaki fragmentsThe average Okazaki fragment length is around 1000 to 2000 nucleotides in prokaryotes, but only 100 to 200 nucleotides in eukaryotes. The most prominent difference is the length of the Okazaki fragments. Thus, lagging strand synthesis is a multistep process involving sophisticated coordination among different molecules.ĭue to the different genome sizes of prokaryotes and eukaryotes, the process of lagging strand synthesis differs between them. 4) The leading strand is synthesized as a continuous piece, whereas the lagging strand is synthesized as a series of shorter pieces called Okazaki fragments. 3) After initial primer synthesis, the leading strand needs only DNA polymerase for replication to continue, whereas the lagging strand needs multiple enzymes, including DNA polymerase I, RNase H, and ligase. 2) For leading strand synthesis, a single primer is needed, whereas multiple RNA primers are required for lagging strand synthesis. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the opposite direction. There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand. Replication first begins on the leading strand. This final task is performed by the enzyme DNA ligase, which joins the 3’ end of one fragment with 5’ end of another in order to make the discontinuous lagging strand into a continuous one.ĭuring replication, the complementary strands in double-stranded DNA are synthesized at different rates. However, the DNA polymerase cannot fill the nicks present between Okazaki fragments. The enzyme RNase H then removes the RNA primers interspersed between the Okazaki fragments.Īnother DNA polymerase then fills the empty spaces left after the removal of the RNA primers. The resultant short DNA fragments are known as Okazaki fragments. This cycle of primer synthesis by primase and subsequent DNA elongation by polymerase continues along the lagging strand. Then, DNA polymerase synthesizes DNA onto the end of the primer until it encounters the next primer. After replacing RNA primer with deoxyribonucleic acid and their polymerisation, Okazaki fragments are joined together by means of enzymes, DNA ligase (Khorana. The enzyme DNA primase, which is present close to the opening of the replication fork, will synthesize multiple RNA primers on the lagging strand as the DNA unwinds. To deal with this problem, DNA synthesis is carried out discontinuously in a 5' to 3' direction. However, DNA polymerase cannot synthesize DNA in a 3' to 5' direction on the lagging strand. Because of this, the leading strand is synthesized continuously. On the other strand, the replication process is discontinuous, relatively slower, and starts slightly later this daughter strand is known as the lagging strand.ĭNA polymerase can only synthesize DNA in the 5' to 3' direction. On one strand, the replication process is continuous and fast this newly formed daughter strand is called the leading strand. The complementary strands in double-stranded DNA replicate at different rates.
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