Concurrent synthesis on the leading and lagging strands
Download as PPTX, PDF1 like1,947 views
DNA replication occurs concurrently on the leading and lagging strands. The leading strand runs in the same direction as the replication fork and allows for continuous DNA synthesis. The lagging strand runs in the opposite direction and requires discontinuous DNA synthesis in fragments called Okazaki fragments. DNA polymerase III is the main polymerase in E. coli, consisting of a dimer core enzyme and accessory proteins that allow for high processivity of DNA synthesis on both strands concurrently.
Concurrent synthesis on the leading and lagging strands
- 2. LEADINGAND LAGGING STRAND The parent strand that runs 5’-3’ in the reverse direction of fork movement is termed the leading strand ,and it serves as a template for the continuous DNA synthesis. The other parent strand that runs 5’-3’ in the direction of fork movement is termed the lagging strand , and it serves as a template for the discontinuous strand .
- 3. DNAPolymerase III It is a haloenzyme consist of a dimer containing 10 different polypeptide unit. This haloenzyme is main polymerase of E. coil. It is made up of three assemblies : • Clamp loading complex • B sliding clamp processivity factor • Core enzyme
- 4. Fig. showing the concurrent DNAsynthesis on the leading and the lagging strand
- 5. CONCLUSION • Concurrent DNA may be achieved on both the leading and lagging strand at a single replication fork . • The lagging template strand is “looped” in order to invert the physical direction of synthesis , but not the biochemical direction. • The enzyme functions as a dimer with each core enzyme achieving synthesis on one or the other strand.
- 6. THANKYOU