Search results
Results from the WOW.Com Content Network
In bacteria, the coding regions typically take up 88% of the genome. [1] The remaining 12% does not encode proteins, but much of it still has biological function through genes where the RNA transcript is functional (non-coding genes) and regulatory sequences, which means that almost all of the bacterial genome has a function. [1]
Pseudogenes are a type of junk DNA. Most non-bacterial genomes contain many pseudogenes, often as many as functional genes. This is not surprising, since various biological processes are expected to accidentally create pseudogenes, and there are no specialized mechanisms to remove them from genomes.
Non-B DNA can have significant implications for DNA biology and human health. For example, Z-DNA has been implicated in immunity and autoimmune diseases, such as lupus and arthritis. [6] H-DNA has been implicated in genomic instability and cancer, and G-quadruplexes have been linked to telomere maintenance, [7] oncogene activation, and cancer. [8]
Non-functional DNA is rare in bacterial genomes which typically have an extremely high gene density, with only a few percent being not protein-coding. [60] However, in most animal or plant genomes, a large fraction of DNA is non-functional, given that there is no obvious selective pressure on these sequences.
For instance, the EcoRV enzyme shown to the left recognizes the 6-base sequence 5′-GATATC-3′ and makes a cut at the horizontal line. In nature, these enzymes protect bacteria against phage infection by digesting the phage DNA when it enters the bacterial cell, acting as part of the restriction modification system. [129]
The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. [ 3 ] Introns are found in the genes of most eukaryotes and many eukaryotic viruses and they can be located in both protein-coding genes and genes that function as RNA ( noncoding genes ).
Transgene describes a segment of DNA containing a gene sequence that has been isolated from one organism and is introduced into a different organism. This non-native segment of DNA may either retain the ability to produce RNA or protein in the transgenic organism or alter the normal function of the transgenic organism's genetic code.
The term plasmid was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." [11] [12] The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time ...