Differences between DNA Polymerase I, II, and III

[Fractal314]

What are DNA polymerase? Why do they have to exist? Why do RNA primers need to be primed? Is the idea of priming, just connecting the 3' to the 5'? What is the difference between the polymerase I, II, III?

Homework Equations

I have no clue how to answer this and my textbook makes me completely lost. If anybody can help that would be great.

 

[chemisttree]

You need to get to googling...

 

[Blueshift5]

DNA polymerases are enzymes responsible for the replication of DNA during cell division. There are multiple types of DNA polymerases, with the three main ones being DNA polymerase I, II, and III. Each of these polymerases have different functions and play different roles in the replication process.

DNA polymerase I is primarily involved in DNA repair and removing RNA primers during replication. It has a 5' to 3' polymerase activity, meaning it can add nucleotides to the growing DNA strand in the 5' to 3' direction, as well as a 3' to 5' exonuclease activity, allowing it to remove RNA primers and replace them with DNA nucleotides.

DNA polymerase II is also involved in DNA repair, but has a different function than DNA polymerase I. It has a 3' to 5' exonuclease activity, which allows it to proofread and correct any mistakes made during DNA replication.

DNA polymerase III is the main replicative polymerase in prokaryotic cells. It has a high processivity, meaning it can add multiple nucleotides without falling off the DNA strand, allowing for faster replication. It also has a 5' to 3' polymerase activity and a 3' to 5' exonuclease activity, making it able to both add nucleotides and correct any mistakes made during replication.

RNA primers are short segments of RNA that are needed to initiate DNA replication. They are necessary because DNA polymerases can only add nucleotides to an existing DNA strand, not start a new one. Therefore, RNA primers are needed to provide a starting point for DNA polymerases to add nucleotides and begin replication.

The idea of priming is not just connecting the 3' to the 5'. Priming refers to the process of initiating DNA replication by adding a short RNA primer to the 3' end of the DNA strand. The DNA polymerase then uses this primer to start adding DNA nucleotides in the 5' to 3' direction.

In summary, DNA polymerases are essential enzymes for DNA replication, with different types having specific functions and roles. RNA primers are necessary for DNA replication to begin, and the idea of priming refers to the process of initiating DNA replication by adding a primer to the DNA strand.