DNA (Deoxyribonucleic acid)

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DNA, with it's ability to replicate and control life, is perhaps the most powerful substance on Earth

Structure of DNA



Define replication: Replication is the process where DNA makes a copy of itself. DNA needs to copy itself since for an organism to grow or reproduce there must be cell division. And every new cell needs a copy of the DNA, the genetic instructions, to know how to be a cell and what its function is (literally) in life.

DNA replicates right before a cell divides. DNA replication is semi-conservative. That means that when it makes a copy, each new molecule would consist of one old strand and one new strand. This helps reduce the number of copy errors. Genetic (biological) information is copied and eventually transferred from parent to off-spring. This is the phenomena of heridity. This can only happen if DNA replicates accurately.

How does it happen: Replication is performed by splitting (unzipping) the double strand of the DNA molecule down the middle via relatively trivial chemical reactions. It then recreates the "other half" of each new single strand by drowning each half in a "soup" containing the four bases. Since each of the "bases" can only combine with one other base (the rules of complementary base pairing must be complied with), the base on the old strand, acting as a template, dictates which base will be on the new strand, since A always combines with T and C with G. This way, each split half of the strand plus the bases it collects or scavanges from the 'soup' which then fasten to the growing strand, will ideally end up as a complete replica of the original (unless a mutation occurs). So the genetic instructions can be passed from cell to cell and ultimately from generation to generation.

Enzymes are the machinery required to accomplish this DNA replication. In what has often been referred to as 'life's molecular dance' we have to admire and awe at the incredible choreography involved. There are various types of enzymes involved, each with their own seperate functions and responsiblies such as;

  • initiating the unwinding
  • the unwinding itself
  • capturing the appropriate complementary bases floating through its environment to maintain the correct sequence
  • the binding of these bases to the growing second strand
  • proof-reading activities to ensure the right bases are inserted
  • cutting away mistakes it might have made