DNA replication: steps
Solution
DNA replication is a complex process involving several steps:
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Initiation: The DNA double helix unwinds at the origin of replication, creating a replication fork. This is facilitated by the enzyme helicase, which breaks the hydrogen bonds between the base pairs.
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Primer Binding: The enzyme RNA primase synthesizes a short RNA primer on each template strand as a starting point for replication.
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Elongation: DNA polymerase III starts adding new DNA nucleotides at the RNA primer. It moves along the template strand in a 3' to 5' direction, synthesizing the new DNA strand in a 5' to 3' direction.
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Removal of RNA Primers: The RNA primers are removed by DNA polymerase I and replaced with DNA.
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Ligation: The enzyme DNA ligase seals the gaps between the Okazaki fragments (short DNA sequences synthesized on the lagging strand) to create a continuous DNA strand.
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Termination: Once the entire DNA molecule has been replicated, termination occurs. In circular DNA (like in bacteria), replication stops when the two replication forks meet. In linear DNA (like in humans), replication ends at specific sequences called telomeres.
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Proofreading: DNA polymerase also has proofreading ability. It checks the newly synthesized DNA for errors and corrects them. This ensures the accuracy of DNA replication.
This is a simplified overview of the process. The actual process is much more complex and involves many more proteins and enzymes.
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