Template (genetics)
As a template in which is genetics a source DNA , or - - RNA strand designates that serves as a template in the construction of a complementary DNA or RNA strand.
In the synthesis of a nucleic acid strand under the action of polymerases , the sequence of its building blocks, the nucleotides , is specified in each case via complementary base pairing by the sequence of nucleobases in the template strand . The information stored in the form of the fixed formation is thus passed on in the newly formed nucleotide sequence . However, the newly synthesized strand now has a sequence of bases that is complementary to the template and runs in its direction (5 '→ 3') towards the template.
Two strands of nucleic acids paired in this way - made of DNA / DNA, RNA / RNA or hybrid DNA / RNA or RNA / DNA - are always in opposite directions, they run anti-parallel . Nucleic acids are synthesized in the 5 '→ 3' direction; the present matrix is read 3 '→ 5' in the opposite direction.
The genetic term was introduced in the printing industry based on the term matrix . A similar derivation took place in the English technical language, here the matrix is referred to as template (English for "template" or "template").
Examples
During DNA replication , the double strand of DNA is first untied by a topoisomerase and opened by helicases . The two single strands then serve as templates on which the two new strands are synthesized by a DNA-dependent DNA polymerase .
In the transcription of genes which serves codogenic strand of the DNA as a template to create the mRNA by a DNA-dependent RNA polymerase .
Telomerase is an enzyme that uses an RNA template to synthesize the DNA sequence of telomeres at the ends of eukaryotic chromosomes . Such an RNA-dependent DNA polymerase is also the reverse transcriptase of retroviruses . The genome of RNA viruses such as poliovirus is amplified by an RNA-dependent RNA polymerase .
source
- Rolf Knippers: Molecular Genetics. Georg Thieme Verlag, 9th edition, 2006. ISBN 978-3-13-477009-4 ( limited preview in Google book search).