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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 as a small RNA fragment marking the start of the new strand, and that DNA polymerase III needs it to begin adding nucleotides. It also notes that, because it contains uracil instead of thymine, DNA polymerase I later removes it and replaces it with DNA.

Relations

Sources · original ES transcript

  • The Rule Behind All Life | The Central Dogma5:49
    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.
  • The Rule Behind All Life | The Central Dogma6:30
    Estos fragmentos inician con el ARN de los cebadores que, al contener uracilo en lugar de timina, deben ser reemplazados por ADN para asegurar la fidelidad genética. Esta tarea es realizada por la DNA polimerasa I, que elimina los primers de ARN y los sustituye por nucleótidos de ADN.
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