DNA replication
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.[1] 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.[2] As the DNA unwinds at the origin, the synthesis of new strands forms at a replication fork. In addition to DNA polymerase,[3] 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.[4] 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.[5] 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.
[change] References
- ↑ 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
