![]() ![]() TWS was supported by the German Research Foundation (DFG) through IRTG 1360 (International Research Training Group). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: MB was supported by the Network of Excellence of the European Commission, Project ENFIN, contract number LSHG-CT-2005-518254. Received: JAccepted: MaPublished: April 27, 2010Ĭopyright: © 2010 Spiesser et al. Half of the parent DNA molecule is conserved in each of the two daughter DNA molecules.Citation: Spiesser TW, Diener C, Barberis M, Klipp E (2010) What Influences DNA Replication Rate in Budding Yeast? PLoS ONE 5(4):Įditor: Stefan Wölfl, Universität Heidelberg, Germany DNA replication is a semi-conservative process. You can see a detailed animation of the process at this link: (2:05).ĭNA Replication. The process of DNA replication is actually much more complex than this simple summary. ![]() DNA replication is a semi-conservative process because half of the parent DNA molecule is conserved in each of the two daughter DNA molecules. As a result, the two daughter molecules are both identical to the parent molecule. The two daughter molecules that result each contain one strand from the parent molecule and one new strand that is complementary to it. This exposes the bases inside the molecule so they can be “read” by another enzyme, DNA polymerase, and used to build two new DNA strands with complementary bases, also by DNA polymerase. DNA replication begins when an enzyme, DNA helicase, breaks the bonds between complementary bases in DNA (see Figure below). It occurs during the synthesis (S) phase of the eukaryotic cell cycle. DNA replication is the process in which DNA is copied. Knowledge of DNA’s structure helped scientists understand how DNA replicates. These base pairs (A-T or G-C) stick into the middle of the double helix, forming, in essence, the steps of the spiral staircase. This maintains the uniform shape of the DNA double helix. However, when a one-ring molecule binds with a two-ring molecule, the distance between the two chains is kept constant. If adenine were to bind with guanine and cytosine with thymine, the distance between the two DNA chains would be variable. ![]() Adenine and guanine have a two-ring structure. If you look at the nitrogen bases in Figure above, you will see why. Cytosine always bonds with its complementary base, guanine. Adenine always bonds with its complementary base, thymine. Scientists concluded that bonds (hydrogen bonds) between complementary bases hold together the two polynucleotide chains of DNA. Each nucleotide consists of a sugar (deoxyribose), a phosphate group, and a nitrogen-containing base (A, C, G, or T). DNA, as a nucleic acid, is made from nucleotide monomers, and the DNA double helix consists of two polynucleotide chains. The double helix shape of DNA, together with Chargaff’s rules, led to a better understanding of DNA. Do you see the resemblance? Which parts of the DNA molecule are like the steps of the spiral staircase? This is the same basic shape as a spiral staircase. The DNA molecule has a double helix shape. You can learn more about Franklin’s work by watching the video at this link: (7:47). ![]() Franklin and these other scientists have not always been given credit for their contributions. The discovery was based on the prior work of Rosalind Franklin and other scientists, who had used X rays to learn more about DNA’s structure. James Watson and Francis Crick are usually given credit for discovering that DNA has a double helix shape, like a spiral staircase (see Figure below). As you will soon see, the model predicts how the DNA sequence can code for proteins, and how the molecule can be replicated.Īfter DNA was found to be the genetic material, scientists wanted to learn more about it. In an extremely elegant model, that's how. ![]()
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