Long terminal repeats are identical sequences of DNA that repeat hundreds or thousands of times found at either end of retrotransposons or proviral DNA formed by reverse transcription of retroviral RNA. They are used by viruses to insert their genetic material into the host genomes.

Insertion in an intron altered splicing pattern/splicing failure. It usually results in protein truncation or the production of inactive mis-spliced products, although more complex effects are common.

Poly A plays a role both in dimerization and genome packaging since it is necessary for cleavage and polyadenilation. It has been reported that sequences upstream (U3 region) and downstream (U5 region) are needed in order to make the cleavage process efficient.

The first ORF encodes a RNA-binding protein of 500 amino acid lengths that weighs 40 kDA. This protein contains a leucine zipper motif and functions as a chaperone.

The mutation in the melanocortin-4 receptor protein (MC4R) which is a component of leptin-melanocortin pathway was detected to be related to obesity. The common monogenic obesity disorder was represented by MC4R deficiency. The obesity was accounted due to homozygous and heterozygous mutations in MC4R.

Group II introns is a large class of self-catalytic ribozymes as well as mobile genetic element found within the genes of all three domains of life. Ribozyme activity (e.g., Self-splicing) can occur under high-salt conditions in vitro.

Conversion of one allele to the other is often due to base mismatch repair during homologous recombination: if one of the four chromatids during meiosis pairs up with another chromatid, as can occur because of sequence homology, DNA strand transfer can occur followed by mismatch repair. This can alter the sequence of one of the chromosomes, so that it is identical to the other.

A helitron is a TE found in eukaryotes that are thought to replicate by a rolling-circle mechanism.

U1 spliceosomal RNA is the small nuclear RNA (snRNA) component of U1 snRNP (small nuclear ribonucleoprotein). Splicing or the removal of introns, is a major aspect of post-transcriptional modification. The U1 snRNP recognizes and binds to the sequence of the 5'-splice site of an intron in a strand of pre-mRNA.  

The RNA component of the small nuclear ribonucleic protein or snRNP is rich in uridine (the nucleoside analog of the uracil nucleotide).

A sequence may be spliced out as an intron or simply retained. This is distinguished from exon skipping because the retained sequence is not flanked by introns. If the retained intron is in the coding region, the intron must encode amino acids in frame with the neighboring exons, or a stop codon or a shift in the reading frame will cause the protein to be non-functional. This is the rarest mode in mammals.

The typical eukaryotic nuclear intron has consensus sequences defining important regions. cc Near the 3' end there is a branch site.

Here, U2 binds to the branch site and ATP is hydrolyzed.

Reverse transcriptase is added, along with deoxynucleotide triphosphates (A, T, G, C). This synthesizes one complementary strand of DNA hybridized to the original mRNA strand.

A locked nucleic acid (LNA), often referred to as inaccessible RNA, is a modified RNA nucleotide. The ribose moiety of an LNA nucleotide is modified with an extra bridge connecting the 2' oxygen and 4' carbon.