Why it more efficient to have two different dna polymerases

1. Why does DNA replicate from 5′ to 3′ end, instead of from 3′ to 5′ end?

2. Why do we need DNA polymerase I and not just DNA polymerase III, if polymerase I is just initiating DNA replication and polymerase III does all the “heavy lifting” and continues it, why don’t we just use polymerase III? Wouldn’t that be more efficient? Why is it more efficient to have two different DNA polymerases?

3.Why is the primer that we use for the beginning of DNA replication made of RNA nucleotides and not DNA nucleotides (deoxynucleotides)?

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