Reverse Transcription

Telomeres and their Structure

• Telomeres are found in birds, reptiles, amphibians, fishes, and mammals, with the common tandem repeat of TTAGGG.
• They are composed of short nucleotide sequences that are repeated multiple times and do not code for any protein.
• In humans, the repetitive sequence is 5'-TTAGGG-3', which is repeated multiple times, whereas in plants, it is TTTAGGG.

Role of Telomeres

• Telomeres are produced as a result of incomplete replication at the end of chromosomes, ensuring that genetic information is preserved and not lost.
• They act as protective end caps, preventing chromosomes from sticking together and protecting from deterioration.
• Telomeres play a vital role in ageing, with each replication cycle resulting in shorter telomeres, eventually leading to senescence and apoptosis when they become too short.

Telomerase Enzyme

• Telomerase is a special enzyme that can increase the length of telomeres.
• It is present in cells that divide unlimited times, such as unicellular eukaryotes, egg and sperm cells, blood cells, and cancer cells.

Reverse Transcription

• Reverse transcription is the conversion of RNA to DNA, where RNA acts as the template in the synthesis of complementary DNA (cDNA).
• The central dogma defines the mechanisms that involve DNA synthesis, RNA synthesis, protein synthesis, and cDNA synthesis.
• Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes.
• The conversion of RNA to DNA is commonly used as a diagnostic tool in laboratory settings for RNA viruses such as HIV, hepatitis, influenza, and coronaviruses.