Template (genetics)

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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.

Scheme of a DNA replication fork . The two DNA strands, whose backbone ( deoxyribose - phosphate ) is shown in turquoise blue, serve as a template . A new DNA strand is built up on each of them via complementary base pairing , the backbone of which is shown in light green. The associated nucleobases are symbolized by their initial letters, the direction of the arrow indicates the direction of synthesis (5 '→ 3'). The result of the replication is two DNA double strands with the same base sequence .

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 .

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