<Li> RNA - Seq: applies next - generation sequencing techniques to sequence whole transcriptomes, which allows the measurement of relative abundance of RNA, as well as the detection of additional variations such as fusion genes, post-transcriptional edits and novel splice sites </Li> <P> Some viruses (such as HIV, the cause of AIDS), have the ability to transcribe RNA into DNA . HIV has an RNA genome that is reverse transcribed into DNA . The resulting DNA can be merged with the DNA genome of the host cell . The main enzyme responsible for synthesis of DNA from an RNA template is called reverse transcriptase . </P> <P> In the case of HIV, reverse transcriptase is responsible for synthesizing a complementary DNA strand (cDNA) to the viral RNA genome . The enzyme ribonuclease H then digests the RNA strand, and reverse transcriptase synthesises a complementary strand of DNA to form a double helix DNA structure ("cDNA"). The cDNA is integrated into the host cell's genome by the enzyme integrase, which causes the host cell to generate viral proteins that reassemble into new viral particles . In HIV, subsequent to this, the host cell undergoes programmed cell death, or apoptosis of T cells . However, in other retroviruses, the host cell remains intact as the virus buds out of the cell . </P> <P> Some eukaryotic cells contain an enzyme with reverse transcription activity called telomerase . Telomerase is a reverse transcriptase that lengthens the ends of linear chromosomes . Telomerase carries an RNA template from which it synthesizes a repeating sequence of DNA, or "junk" DNA . This repeated sequence of DNA is called a telomere and can be thought of as a "cap" for a chromosome . It is important because every time a linear chromosome is duplicated, it is shortened . With this "junk" DNA or "cap" at the ends of chromosomes, the shortening eliminates some of the non-essential, repeated sequence rather than the protein - encoding DNA sequence, that is farther away from the chromosome end . </P>

The structure of dna must be in which complex for transcription to occur