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The nonfunctional DNA in bacterial genomes is mostly located in the intergenic fraction of non-coding DNA but in eukaryotic genomes it may also be found within introns. There are many examples of functional DNA elements in non-coding DNA, and it is erroneous to equate non-coding DNA with junk DNA.
Pseudogenes are nonfunctional segments of DNA that resemble functional genes.Pseudogenes can be formed from both protein-coding genes and non-coding genes. In the case of protein-coding genes, most pseudogenes arise as superfluous copies of functional genes, either directly by gene duplication or indirectly by reverse transcription of an mRNA transcript.
Non-functional DNA elements such as pseudogenes and repetitive DNA, both of which are types of junk DNA, can also be found in intergenic regions—although they may also be located within genes in introns. [2] It is possible that these regions contain as of yet unidentified functional elements, such as non-coding genes or regulatory sequences. [3]
Generalized flowchart of a structural genome annotation pipeline. First, the repetitive regions of an assembled genome are masked by using a repeat library. Then, optionally, the masked sequence is aligned with all the available evidence (ESTs, RNAs, and proteins) of the organism being annotated.
Exonucleases remove these unpaired nucleotides and the gaps are filled by DNA synthesis and repair machinery. [1] [3] Exonucleases may also cause shortening of this junction, however this process is still poorly understood. [4] Junctional diversity is liable to cause frame-shift mutations and thus production of non-functional proteins ...
Deoxyribonucleic acid (DNA) is a nucleic acid containing the genetic instructions used in the development and functioning of all known living organisms. The chemical DNA was discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. The DNA segments that carry this genetic information are called genes.
Gene structure is the organisation of specialised sequence elements within a gene.Genes contain most of the information necessary for living cells to survive and reproduce. [1] [2] In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene.
The mtDNA control region is an area of the mitochondrial genome which is non-coding DNA. This region controls RNA and DNA synthesis. [ 1 ] It is the most polymorphic region of the human mtDNA genome, [ 2 ] with polymorphism concentrated in hypervariable regions .