Why DNA is built in opposite directions and why that matters
In short: DNA replication is a masterpiece of biological engineering. This video breaks down the mechanical constraints of the double helix, explaining how cells manage to copy genetic information with perfect precision despite the physical limitations of their own molecular structure.
DNA replication follows a semi-conservative model, meaning each new molecule contains one original strand and one newly synthesised strand. DNA helicase unwinds the double helix and separates the strands to allow for copying.
DNA polymerase catalyses the formation of phosphodiester bonds to build the sugar-phosphate backbone. Synthesis occurs exclusively in a 5' to 3' direction. The leading strand is synthesised continuously, while the lagging strand is built in discontinuous sections called Okazaki fragments. DNA ligase is the enzyme responsible for joining these Okazaki fragments together.
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Sources
- Summary by Intellect · source: A-Level Biology - DNA Replication | 3 prime and 5 prime ends (2027/28 exams)
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