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Primer

RNA fragment that marks where a new DNA strand begins to be synthesized.

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Primer

RNA fragment that marks where a new DNA strand begins to be synthesized.

It is a short nucleic-acid fragment that provides a free 3′-OH end to initiate synthesis of a new DNA strand. During cellular replication, it is usually made of RNA and base-pairs with the template strand.

The primer resolves the inability of DNA polymerases to begin synthesis de novo. It is required once on the leading strand and repeatedly to form Okazaki fragments on the lagging strand.

The video states that primase synthesizes it at the replication fork and that it allows DNA polymerase III to add nucleotides. Because it contains uracil rather than thymine, DNA polymerase I later removes it and replaces it with DNA.

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Sources · original ES transcript

  • Does DNA Replicate Itself?!0:54
    En la horquilla de replicación, la primasa sintetiza un pequeño fragmento de ARN llamado cebador o primer, que sirve como punto de inicio para la síntesis de la nueva cadena.
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