Replication fork


Replication fork

The replication fork is a structure that forms during DNA replication. It is created by helicases, which break the hydrogen bonds holding the two DNA strands together. The resulting structure has two branching "prongs", each one made up of a single strand of DNA, that are called the leading and lagging strands. DNA polymerase creates new partners for the two strands by adding nucleotides.

Leading strand

to it continuously.

Lagging strand

The lagging strand is the DNA strand opposite the replication fork from the leading strand. It goes from a 3' to 5'.

When replicating, the original DNA splits in two, forming two "prongs" which resemble a fork (i.e. the "replication fork"). DNA has a ladder-like structure; imagine a ladder broken in half vertically, along the steps. Each half of the ladder now requires a new half to match it.

Pol III, the main DNA replication enzyme, cannot work in the 3' to 5' direction of the template strand, and so replication of the lagging strand is more complicated than of the leading strand.

On the lagging strand, primase "reads" the DNA and adds RNA to it in short, separated segments. DNA polymerase III lengthens the primed segments, forming Okazaki fragments. DNA polymerase I then "reads" the fragments, removes the RNA using its flap endonuclease domain, and replaces the RNA nucleotides with DNA nucleotides (this is necessary because RNA and DNA use slightly different kinds of nucleotides). DNA ligase joins the fragments together.

ee also

* [http://www.wehi.edu.au/education/wehi-tv/dna/replication.html More detailed replication fork animation] WEHI-TV


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • replication fork — noun (biology) The site of simultaneous unwinding of duplex DNA and synthesis of new DNA • • • Main Entry: ↑replicate …   Useful english dictionary

  • replication fork — a site on a DNA molecule at which unwinding of the helices and synthesis of daughter molecules are both occurring. Replication fork, showing simultaneous synthesis of both strands; since synthesis occurs in the 5′ to 3′ direction, one …   Medical dictionary

  • replication fork — Point at which DNA strands are separated in preparation for replication. Replication forks thus move along the DNA as replication proceeds …   Dictionary of molecular biology

  • replication fork — Y shaped structure associated with DNA replication. It represents the point at which the strands of double stranded DNA are separated so that replication can proceed …   Glossary of Biotechnology

  • replication fork — The Y shaped structure where DNA is replicated. The arms of the Y contain template strand and a newly synthesized DNA copy …   Dictionary of microbiology

  • Replication de l'ADN — Réplication de l ADN La réplication est le processus au cours duquel l ADN est synthétisé grâce à l ADN polymérase. Ce mécanisme permet à l’ADN d être dupliqué (donc doublé ). Puisque les deux chaînes de l ADN parental se séparent et que deux… …   Wikipédia en Français

  • Réplication de l'adn — La réplication est le processus au cours duquel l ADN est synthétisé grâce à l ADN polymérase. Ce mécanisme permet à l’ADN d être dupliqué (donc doublé ). Puisque les deux chaînes de l ADN parental se séparent et que deux nouvelles molécules sont …   Wikipédia en Français

  • Réplication de l'ADN — La réplication est le processus au cours duquel l ADN est synthétisé grâce à l ADN polymérase. Ce mécanisme permet à l’ADN d être dupliqué (donc doublé). Puisque les deux chaînes de l ADN parental se séparent et que deux nouvelles molécules sont… …   Wikipédia en Français

  • Replication — A turning back, repetition, duplication, reproduction. * * * 1. The execution of an experiment or study more than once so as to confirm the original findings, increase precision, and obtain a closer estimate of sampling error. 2. Autoreproduction …   Medical dictionary

  • DNA replication — DNA replication. The double helix is unwound and each strand acts as a template for the next strand. Bases are matched to synthesize the new partner strands. DNA replication is a biological process that occurs in all living organisms and copies… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.