RNA primer

[percywilkins]

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Does anybody know whether primase creates an RNA primer for the ENTIRE length of the DNA strand, or just the first few nucleotides? Examkrackers says primase creates an RNA primer approx. 10 ribonucleotides long to initiate the strand. Does that mean that DNA polymerase will add to those first 10, and then do the rest on its own? Or does primase create a primer for the entire strand, so that polymerase can add to the primer. That would make more sense, but I'm not sure if thats how its done. I'm so confused!

 

[Schaden Freud]

Does anybody know whether primase creates an RNA primer for the ENTIRE length of the DNA strand, or just the first few nucleotides? Examkrackers says primase creates an RNA primer approx. 10 ribonucleotides long to initiate the strand. Does that mean that polymerase will add to those first 10, and then do the rest on its own? I'm so confused!

Yeah the RNA primer is very short and the rest of the work is done by DNA polymerase. The RNA primer is subsequently removed and replaced with DNA.

 

[GuzzyRon]

Does anybody know whether primase creates an RNA primer for the ENTIRE length of the DNA strand, or just the first few nucleotides? Examkrackers says primase creates an RNA primer approx. 10 ribonucleotides long to initiate the strand. Does that mean that DNA polymerase will add to those first 10, and then do the rest on its own? Or does primase create a primer for the entire strand, so that polymerase can add to the primer. That would make more sense, but I'm not sure if thats how its done. I'm so confused!

Yes and no. Yes primase creates just one primer (a few nucleotides long) for the LEADING strand. Then DNA polymerase continues from there. No more than one primer is necessary for the leading strand because it is synthesized CONTINUOUSLY.

One the other hand, primase creates a LOT of primers for the LAGGING strand. In fact, it creates one primer for each Okazaki fragment. This is because the lagging strand is synthesized DISCONTINUOUSLY (in bits and pieces, so to say). DNA polymerase then comes around and add DNA to the primers which are then joined together by ligase.

I'm not too bright but this much I know.