Replication Fork Overview

[julianj]

Transcribed the end of this.

DNA polymerases (III and I) are the primary enzymes responsible for DNA replication. DNA polymerases need a template, they cannot synthesize without a template and cannot create new polymers, they can only extend existing strands by adding new nucleotides to one end. Primase (RNA polymerase) must create short priming sequences before DNA polymerases can carry out their function. Primases can create new polymers by adding bases to complementary strand in absence of existing primer. Once RNA primers are established, DNA polymerases can continue the elongation process. RNA primers need to be removed prior to the end of the replication process. DNA polymerase I, which has endonuclease activity performs this task. DNA polymerases can only add nucleotides to the 3' hydroxyl end of the nucleotide polymer. Since the two strands are anti-parallel. Double strand formation has to proceed in opposite directions on each of the two template strands at the replication fork. In one direction DNA is replicated as a continuous strand, this is called the leading strand. Replication on the other strand occurs by the creation of my short segments, this is called the lagging strand. Replication in both the leading and lagging begins with primase adding a short 3 to 10 base RNA primer to this template strand. Once the primer is added, DNA polymerase III elongates the strand by adding DNA nucleotides to the 3' hydroxyl end of the growing polymer. The creation of primer using primase and elongation by DNA polymerase III is adequate to form long stretches of DNA on the leading strand. On the lagging strand the new strands 3' hydroxyl end points away from the replication fork. This forces the elongation process to occur in a discontinuous manner. As replication moves along template strand series of shorter DNA polymers are formed. Each strand is initiated by its own RNA primer. The short lengths of dsDNA formed along the lagging strand are called Okazaki fragments. When Okazaki fragment extends to point it overlaps with the previous RNA primer, RNA nucleotides are removed and replaced with DNA. This requires DNA polymerase I's exonuclease activity.

[AabidIsmail]

Very well explained than all other videos out there

[wendy]

thanks for the information 😃
I have a homework of this

[markateuscher]

2:19 isn't this determined by the father in the body