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Semiconservative replication describes the mechanism of DNA replication in all known cells. DNA replication occurs on multiple origins of replication along the DNA template strands. As the DNA double helix is unwound by helicase, replication occurs separately on each template strand in antiparallel directions. This process is known as semi ...
DNA was extracted periodically and was compared to pure 14 N DNA and 15 N DNA. After one replication, the DNA was found to have intermediate density. Since conservative replication would result in equal amounts of DNA of the higher and lower densities (but no DNA of an intermediate density), conservative replication was excluded.
The process of semiconservative replication for the site of DNA replication is a fork-like DNA structure, the replication fork, where the DNA helix is open, or unwound, exposing unpaired DNA nucleotides for recognition and base pairing for the incorporation of free nucleotides into double-stranded DNA.
As a result of semi-conservative replication, the new helix will be composed of an original DNA strand as well as a newly synthesized strand. [7] Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication.
[4] [5] This process is considered semi-conservative because, after replication, each copy of DNA contains a strand from the original DNA molecule and a strand from the newly-synthesized DNA molecule. [5] An RNA primer is a short chain of single-stranded RNA, consisting of roughly five to ten nucleotides complementary to the DNA template strand.
Complementary base pairing takes place, forming a new double-stranded DNA molecule. This is known as semi-conservative replication since one strand of the new DNA molecule is from the 'parent' strand. Continuously, eukaryotic enzymes encounter DNA damage which can perturb DNA replication.
DNA is a duplex formed by two anti-parallel strands. Following Meselson-Stahl, the process of DNA replication is semi-conservative, whereby during replication the original DNA duplex is separated into two daughter strands (referred to as the leading and lagging strand templates). Each daughter strand becomes part of a new DNA duplex.
Both of these follow a similar pattern, called semi-conservative replication, in which individual strands of DNA are produced in different directions, which makes a leading and lagging strand. These lagging strands are synthesized by the production of Okazaki fragments that are soon joined.