The main difference between leading and lagging strand is that the leading strand is the DNA strand, which grows continuously during DNA replication whereas lagging strand is the DNA strand, which grows discontinuously by forming short segments known as Okazaki fragments. Therefore, to form a continuous strand, the leading strand does not require ligase while the lagging strand requires ligase to ligate Okazaki fragments together. Furthermore, the leading strand opens in the 3’ to 5’ direction while the lagging strand opens in the 5’ to 3’ direction. Show
Leading and lagging strand are two terms that we use to describe the two strands of the double-stranded DNA during DNA replication based on the pattern of strand growth. Key Areas Covered1. What is a Leading Strand Key TermsDNA replication, Leading Strand, Lagging Strand, Okazaki Fragments, Replication Fork Leading strand is one of the two strands of the DNA double helix. Generally, DNA undergoes replication during the cell cycle as a step of preparing the cell for the division. DNA polymerase is the enzyme that is responsible for DNA replication carried out exclusively in the 5’ to 3’ direction. During the process, each strand of the DNA double helix serves as templates for replication. Therefore, the process of DNA replication is known as a semiconservative process where each newly synthesized DNA double helix composes an old and a new DNA strand Figure 1: DNA Replication. During replication, the DNA double helix unwinds to form the replication fork. Here, the DNA strand, which opens up in the 3’ to 5’ direction allows the growth of the strand continuously in the 5’ to 3’ direction. Therefore, we call this strand as the leading strand. In the leading strand, DNA polymerase can add nucleotides continuously, and the growth of the new DNA strand occurs towards the replication fork. What is a Lagging StrandThe lagging strand is the second strand of the DNA double helix. The strand opens up in the 5’ to 3’ direction. Therefore, the new strand growth has to occur away from the replication fork as the direction of DNA replication occurs only in the 5’ to 3’ direction. On that account, the replication process is not continuous, and it occurs through the formation of Okazaki fragments. Generally, Okazaki fragments are short segments of DNA, about 1000-2000 nucleotides long. Figure 2: Continuity of the Leading and Lagging Strand Also, at the beginning of each Okazaki fragment, an RNA primer has to be synthesized on the lagging strand. RNA primase is the enzyme responsible for the synthesis of RNA primers on the template DNA during DNA replication. The growth of the last Okazaki fragment stops at the 5’ end of the RNA primer of the former Okazaki fragment. Significantly, the DNA replication of the lagging strand always has a ‘wait time’ for the synthesis of a new RNA primer. Ultimately, the RNA primers are removed from the strand and DNA polymerase fills the missing nucleotides. Then, DNA ligase joins each DNA fragment together on the lagging strand, making a continuous DNA strand. Similarities Between Leading and Lagging Strand
Difference Between Leading and Lagging StrandDefinitionLeading strand refers to one of two strands of DNA found at the replication fork, being replicated continuously while lagging strand refers to the other strand found at the replication fork, replicating discontinuously in the 5′ to 3′ direction. Thus, this is the main difference between leading and lagging strand. Type of Growth during DNA replicationImportantly, the leading strand grows continuously while the lagging strand grows discontinuously by forming Okazaki fragments. The direction of the Template in the Replication ForkFurthermore, another important difference between leading and lagging strand is that the leading strand opens up in the 3’ to 5’ direction while the lagging strand opens up in the 5’ to 3’ direction. The direction of Strand GrowthLeading strand grows in the 5’ to 3’ direction while the lagging strand grows in the 3’ to 5’ direction. PrimersLeading strand requires a single primer for the synthesis while the lagging strand requires a new primer to start each Okazaki fragment. Hence, this is another difference between leading and lagging strand. The beginning of the ReplicationMoreover, the starting point too contributes to the difference between leading and lagging strand. The leading strand starts to grow at the beginning of replication while the lagging strand starts to replicate shortly after. Direction from the Replication ForkAlso, the leading strand grows towards the replication fork while the Okazaki fragments of the lagging strand grow away from the replication fork. Speed of FormationAdditionally, the speed of formation is another difference between leading and lagging strand. The formation of the leading strand occurs at high speed while the formation of the lagging strand occurs slowly. The requirement of DNA LigaseBesides these, the leading strand does not require DNA ligase while the lagging strand requires DNA ligase to ligate Okazaki fragments together. ConclusionLeading strand is one of the two strands of the double-stranded DNA. Significantly, it opens up in the 3’ to 5’ direction at the replication fork. Therefore, it undergoes strand growth continuously in the 5’ to 3’ direction during the DNA replication. In comparison, the lagging strand is the other strand in the DNA double helix. However, it opens up in the 5’ to 3’ direction. Therefore, its strand growth has to occur in the 3’ to 5’ direction. But, usual DNA replication occurs in the 5’ to 3’ direction only. Hence, DNA replication occurs towards the outside of the replication fork discontinuously by forming Okazaki fragments. On that account, the main difference between leading and lagging strand is the direction and the pattern of strand growth. References:1. “What Is DNA Replication?” yourgenome, The Public Engagement Team at the Wellcome Genome Campus, 25 Jan. 2016, Available Here. Image Courtesy:1. “DNA replication en” By LadyofHats Mariana Ruiz
– Own work. Image renamed from File:DNA replication.svg (Public Domain) via Commons Wikimedia What is the difference between the leading strand and lagging strand in DNA replication?The separated DNA strands form a replication fork, where both the DNA strands get replicated forming a lagging and leading strand. The major difference between a lagging and leading strand is that the lagging strand replicates discontinuously forming short fragments, whereas the leading strand replicates continuously.
What is the difference between leading and lagging?Therein lies the main difference between the two: A leading indicator looks forward at future outcomes and events. A lagging indicator looks back at whether the intended result was achieved.
What are the leading and lagging strands in DNA replication?During DNA replication, one new strand (the leading strand) is made as a continuous piece. The other (the lagging strand) is made in small pieces. DNA replication requires other enzymes in addition to DNA polymerase, including DNA primase, DNA helicase, DNA ligase, and topoisomerase.
What makes the leading and lagging strands of DNA replication different quizlet?The leading strand is built continuously, and the lagging strand is built in pieces. The leading strand is build continuously, and the lagging strand is built in pieces. During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?
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