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Unit 6

6.2 Replication

1 min readmay 31, 2020


Lani Himegarner

AP Biology 🧬

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Replication is the process in which genetic information is passed on to the next generation. In eukaryotes, this process takes place in the nucleus of the cell. Because prokaryotes do not have a nucleus, this process occurs in the cytoplasm. This is a multi-step process that employs the help of multiple enzymes.

🧬 DNA and RNA

Helicase unwinds the DNA strands so that the topoisomerase can relax the coil in front of the replication fork. DNA polymerase reads the conserved DNA strand to synthesize new strands of DNA. RNA primers work with the DNA polymerase to build the complementary strand.

Image courtesy of WikiMedia Commons.

The Leading Strand

Replication is a “semiconservative” process, meaning it conserves one strand of DNA, unchanged, to serve as a template to create another. The DNA is processed in the 5’ → 3’ direction, or what is called the leading strand. DNA polymerase works continuously on the Leading Strand but has to work in sections on the lagging strand (because it is 3’ → 5’). These sections are known as Okazaki fragments. Ligase then connects these fragments on the lagging strand.
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