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DNA Replication
DNA replication is a fundamental biological process that allows cells to produce exact copies of their
genetic material before cell division
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The cell unwinds the double helix of DNA
and separates the two strands, creating a replication fork
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DNA polymerase is the enzyme responsible for DNA replication
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This ensures that the genetic information is preserved during cell division
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DNA replication is a highly accurate process, with an error rate of less than one mistake per billion
nucleotides added
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These proteins work together to unwind the DNA, create primers for DNA polymerase to start
replication, and join the newly synthesized DNA fragments together
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DNA replication can be disrupted by various factors, such as DNA damage or mutations in the DNA
polymerase gene
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PROCESS OF REPLICATION
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These sites are recognized by a complex of proteins that bind to the DNA and separate the
two strands to form a replication bubble
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Unwinding: Once the replication bubble is formed, helicase enzymes are recruited to separate the two
strands of DNA by breaking the hydrogen bonds between the complementary base pairs
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Priming: The next step in DNA replication is priming, in which primase enzymes synthesize a short
RNA primer on each strand of DNA
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The leading strand is
synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki
fragments
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Proofreading: As the nucleotides are added to the new strand of DNA, DNA polymerase proofreads
the sequence to ensure that the correct nucleotide has been added
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The two new strands of DNA are then
separated, forming two identical copies of the original DNA molecule
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Any errors or disruptions in this
process can lead to mutations, genetic disorders, and diseases
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Here are the roles of various enzymes involved in DNA replication:
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This creates a replication fork, where the two strands of DNA
are separated and serve as templates for DNA synthesis
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Topoisomerase: Topoisomerase is an enzyme that relieves the torsional stress that is generated as the
DNA strands unwind
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These primers provide a starting point for DNA polymerase to begin synthesizing new DNA
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DNA polymerase: DNA polymerase is the enzyme responsible for synthesizing the new strand of
DNA
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These enzymes add nucleotides to the new strand of DNA in a 5' to 3'
direction and proofread the sequence to ensure that the correct nucleotide is added
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DNA ligase: DNA ligase is an enzyme that joins the Okazaki fragments on the lagging strand of
DNA
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Overall, the roles of these enzymes are critical for the successful completion of DNA replication,
ensuring that the genetic information is accurately copied and transmitted to the next generation of cells