Biology as Poetry: Genetics

Bacteriophage Ecology Group

DNA Replication

Means by which the hereditary material associated with most organisms, including all cellular organisms, is duplicated in the course of growth, reproduction, etc.

DNA replication occurs via a process termed semiconservative replication. It occurs in association with what are known as replication forks and involves numerous proteins including DNA polymerase, primase, helicase, single-strand binding protein, DNA ligase, and also DNA gyrase.

The results of DNA replication are proofread in the course of polymerization and otherwise a number of strategies are employed to assure that the process of replication occurs with high accuracy, particularly such that base sequence is only relatively rarely modified, that is, mutated.

Because of the 5' to 3' polarity of DNA, the antiparallel arrangement of the strands making up the DNA double helix, and because DNA replication occurs solely in the 5' to 3' direction, there exist per replication fork what are known as a leading strand and a lagging strand. While the leading strand displays continuous synthesis of DNA, with the lagging strand there is discontinuous synthesis, resulting in the formation of Okazaki fragments that then must be ligated together for form unbroken strands of daughter DNA.

There exist a few variations on DNA replication such as what is known as rolling circle replication, as seen in ssDNA viruses, and replication that is initiation by recombination, as seen in other virus types.

In eukaryotes, there also is the synthesis of telomere, which is effected by an enzyme known as telomerase. Unlike DNA replication which id catalyzed by DNA polymerase, telomere synthesis does not involve a DNA template.

For more on this topic, see Wikipedia  and Google.  Contact web master.  Return to home.