DNA replication is the process of copying a double-stranded DNA molecule. Both strands serve as templates for the reproduction of the opposite strand. This process occurs in all life forms with DNA. There are some differences in the control of DNA replication in prokaryotic and eukaryotic organisms.
In a cell, DNA replication begins at specific places in the genome, called origins. As the DNA unwinds at the origin, the synthesis of new strands forms at a replication fork. In addition to DNA polymerase, other enzymes at the fork help to start and continue the DNA synthesis.
[change] DNA polymerase
DNA polymerases are a family of enzymes that carry out all forms of DNA replication. However, a DNA polymerase can only extend an existing DNA strand paired with a template strand; it cannot begin the synthesis of a new strand. To begin synthesis, a short fragment of DNA or RNA, called a 'primer', is created and paired with the template DNA strand.
In general, DNA polymerases are extremely accurate, making less than one mistake for every 107 (10 million) nucleotides added. Even so, some DNA polymerases also have 'proofreading' ability: they can remove nucleotides from the end of a strand in order to correct mismatched bases.
- Most viruses use RNA instead.
- Berg JM, Tymoczko JL, Stryer L, Clarke ND (2002). Biochemistry. W.H. Freeman. ISBN 0-7167-3051-0.Chapter 27, Section 4: DNA Replication of both strands proceeds rapidly from specific start sites
- The enzyme which synthesizes new DNA by adding nucleotides matched to the template strand.
- Berg JM, Tymoczko JL, Stryer L, Clarke ND (2002). Biochemistry. W.H. Freeman. ISBN 0-7167-3051-0. Chapter 27, Section 2: DNA Polymerases require a template and a primer
- McCulloch SD, Kunkel TA (January 2008). "The fidelity of DNA synthesis by eukaryotic replicative and translesion synthesis polymerases". Cell Research 18 (1): 148–61. doi:10.1038/cr.2008.4. PMID 18166979.
[change] Other websites
- DNA Workshop
- WEHI-TV - DNA Replication video- Detailed DNA replication animation from different angles with description below.
- Basic Polymerase Chain Reaction Protocol
- Animated Biology
- DNA makes DNA (Flash Animation)
- DNA replication info page by George Kakaris MSc.
- Reference website on eukaryotic DNA replication