Käänteistranskriptaatio

Käänteistranskriptaatio, often translated as reverse transcription, is a process where RNA is used as a template to synthesize a complementary DNA (cDNA) molecule. This biological mechanism is primarily carried out by enzymes called reverse transcriptases. These enzymes are found in retroviruses, such as HIV, where they play a crucial role in their replication cycle. Upon entering a host cell, the retrovirus releases its RNA genome and reverse transcriptase. The reverse transcriptase then uses the viral RNA to create a DNA copy. This viral DNA is subsequently integrated into the host cell's genome, allowing the virus to hijack the cell's machinery to produce more viral particles.

Beyond retroviruses, reverse transcriptase activity is also observed in eukaryotes. Eukaryotic reverse transcriptases are involved in maintaining the length of telomeres, the protective caps at the ends of chromosomes, and in the transposition of mobile genetic elements called retrotransposons. These elements can copy themselves and insert their DNA into different locations within the genome, contributing to genomic diversity and evolution.

In molecular biology, reverse transcription is a fundamental technique used in laboratories. Scientists utilize isolated reverse transcriptases to convert RNA molecules, such as messenger RNA (mRNA), into cDNA. This cDNA can then be amplified, sequenced, or cloned, providing a stable DNA representation of the original RNA. This technique is essential for studying gene expression, analyzing RNA viruses, and in various diagnostic applications.