what is leading and lagging strand in DNA replication
In DNA replication, the leading strand and the lagging strand refer to the two strands of DNA that are synthesized during the process.
The leading strand is the strand that is synthesized continuously in the 5' to 3' direction, which is the same direction as the replication fork is moving. This means that the DNA polymerase can synthesize the leading strand continuously by adding new nucleotides to the growing DNA strand.
On the other hand, the lagging strand is synthesized discontinuously in the opposite direction of the replication fork, from 3' to 5'. As a result, the DNA polymerase has to synthesize this strand in small fragments called Okazaki fragments. These fragments are later joined together by an enzyme called DNA ligase to form a continuous strand.
Overall, the leading strand is synthesized continuously, while the lagging strand is synthesized in fragments. This is due to the nature of DNA replication, as only one strand can be synthesized in the same direction as the replication fork movement.
Leading and lagging strands are two complementary DNA strands that are synthesized during DNA replication. DNA replication is the process by which an exact copy of DNA is made.
1. Leading Strand: The leading strand is the strand of DNA that is synthesized continuously, or in a continuous fashion, during DNA replication. It is made in the 5' to 3' direction. The synthesis of the leading strand occurs in the same direction as the movement of the replication fork. It requires only one primer to initiate replication and is synthesized continuously by DNA polymerase III.
2. Lagging Strand: The lagging strand is the strand of DNA that is synthesized discontinuously, or in short fragments, during DNA replication. It is made in the opposite 3' to 5' direction. The synthesis of the lagging strand occurs in the direction opposite to the movement of the replication fork. It requires multiple primers to initiate replication and is synthesized in small fragments known as Okazaki fragments. These fragments are later joined by an enzyme called DNA ligase.
In summary, during DNA replication, the leading strand is synthesized continuously and in the same direction as the replication fork, while the lagging strand is synthesized discontinuously and in the opposite direction. Both strands are complementary to each other and together form a replicated DNA molecule.
In DNA replication, the leading and lagging strands refer to the two complementary strands of DNA that are synthesized in opposite directions during the replication process. Let me explain:
1. Leading Strand: The leading strand is the strand of DNA that is synthesized continuously in the 5' to 3' direction. This means that the DNA polymerase synthesizes this strand in the same direction as the replication fork movement. The leading strand is synthesized as a single, continuous piece.
2. Lagging Strand: The lagging strand is the strand of DNA that is synthesized discontinuously in the 5' to 3' direction. This means that the DNA polymerase synthesizes this strand in the opposite direction to the replication fork movement. As a result, small sections called Okazaki fragments are synthesized on the lagging strand.
Here's how the synthesis of the leading and lagging strands occurs:
1. Leading Strand Synthesis:
a. A RNA primer is synthesized at the replication fork by an enzyme called primase.
b. DNA polymerase III binds to the RNA primer and starts synthesizing the leading strand in the 5' to 3' direction. It follows the replication fork and continuously adds nucleotides in the complementary sequence.
2. Lagging Strand Synthesis:
a. Primase synthesizes multiple RNA primers at regular intervals along the lagging strand.
b. DNA polymerase III binds to each RNA primer and synthesizes short Okazaki fragments in the 5' to 3' direction, away from the replication fork.
c. DNA polymerase I replaces the RNA primers with DNA nucleotides.
d. DNA ligase joins the adjacent Okazaki fragments.
This process continues until the entire DNA molecule has been replicated.
To summarize, the leading strand is synthesized continuously in the same direction as the replication fork movement, while the lagging strand is synthesized in a discontinuous manner, forming Okazaki fragments.