Does DNA Ligase ligate the replaced RNA Primer and the leading strand in DNA Replication

[capt34500]

Edit: The title is a little unclear so I'll do my best to reword my question here:

Is DNA Ligase responsible for joining the 3' end of DNA that replaces primer to the rest of the leading strand AND the okazaki fragments in the lagging strand? (This is after the RNA Primes in both strands are replaced with DNA by DNA Polymerase I)

...Or is DNA Ligase only responsible for combining the Okazaki Fragments of the lagging strand?

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[deleted903013]

I believe it's used to connect the DNA after the RNA has been replaced by DNA. The name is "DNA ligase" suggests it joins DNA, not RNA to DNA.

 

[shaqfu2019]

DNA Polymerase I is responsible for replacing the RNA primers with DNA nucleotides on the Okazaki fragment (lagging strand).

 

[capt34500]

I reworded my unclear question. Sorry for the confusion! All help is greatly appreciated !

 

[shaqfu2019]

2nd one

 

[Daniel Schruth]

DNA primase (a type of RNA polymerase) adds RNA primers, which are used to tell DNA Polymerase III where to start DNA replication. Only a single RNA primer is needed for the leading strand, and several are needed for the lagging strand (resulting in Okazaki fragments). It is necessary to add several RNA primers to the lagging strand since DNA can only build in the 5' to 3' direction. So, DNA primase must continuously add RNA primers to the lagging strand as helicase is "unzipping" the DNA. After DNA Polymerase III has built Okazaki fragments along the lagging strand, these RNA primers are replaced with DNA by the enzyme DNA Polymerase I. This is important because we do not want any RNA present on our final DNA strand. However, the problem now is that the DNA we have created has gaps between the Okazaki fragments and the DNA that has replaced the RNA primers. DNA Ligase's function can essentially be thought of as a way to make the replicated DNA strand continuous. Therefore, DNA Ligase would function in connecting the Okazaki fragments and the DNA that has replaced the RNA primers. Hope that helps!