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Nullomers
Nullomers are short sequences of DNA that do not occur in the genome of a species (for example, humans), even though they are theoretically possible. * Nullomers must be under selective pressure - for example, they may be toxic to the cell. Some nullomers have been shown to be useful to treat leukemia, breast, and prostate cancer. They are not useful in healthy cells because normal cells adapt and become immune to them. Nullomers are also being developed for use as DNA tags to prevent cross contamination when analyzing crime scene material. * Background Nullomers are naturally available but potentially unused sequences of DNA. Determining these "forbidden" sequences can improve the understanding of the basic rules that govern sequence evolution. Sequencing the entire genome has shown that there is a high level of non-uniformity in genomic sequences. When a codon is artificially substituted for a synonymous codon, it often results in a lethal change and cell death. This is bel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restriction Site
Restriction sites, or restriction recognition sites, are located on a DNA molecule containing specific (4-8 base pairs in length) sequences of nucleotides, which are recognized by restriction enzymes. These are generally palindromic sequences (because restriction enzymes usually bind as homodimers), and a particular restriction enzyme may cut the sequence between two nucleotides within its recognition site, or somewhere nearby. Function For example, the common restriction enzyme EcoRI recognizes the palindromic sequence GAATTC and cuts between the G and the A on both the top and bottom strands. This leaves an overhang (an end-portion of a DNA strand with no attached complement) known as a sticky end on each end of AATT. The overhang can then be used to ligate in (see DNA ligase) a piece of DNA with a complementary overhang (another EcoRI-cut piece, for example). Some restriction enzymes cut DNA at a restriction site in a manner which leaves no overhang, called a blunt end. Blunt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Chimpanzee
The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of Hominidae, great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative the bonobo was more commonly known as the pygmy chimpanzee, this species was often called the common chimpanzee or the robust chimpanzee. The chimpanzee and the bonobo are the only species in the genus Pan (genus), ''Pan''. Evidence from fossils and DNA sequencing shows that ''Pan'' is a sister taxon to the Human evolution, human lineage and is humans' closest living relative. The chimpanzee is covered in coarse black hair, but has a bare face, fingers, toes, palms of the hands, and soles of the feet. It is larger and more Robustness (morphology), robust than the bonobo, weighing for males and for females and standing . The chimpanzee lives in groups that range in size from 15 to 150 members, although individuals travel and forag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrella term for its three quasi-independent honorific member organizations the National Academy of Sciences (NAS), the National Academy of Engineering (NAE), and the National Academy of Medicine (NAM); and (2) as the brand for studies and reports issued by the operating arm of the three academies, the National Research Council (NRC). The NRC was first formed in 1916 as an activity of the NAS. Now jointly governed by all three academies, the NRC produces some 200 publications annually which are published by the National Academies Press. The reports produced by the National Academies have been characterized as reflective of scientific consensus. History The US National Academy of Sciences was created by an Act of Incorporation dated March 3, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Death
Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as diseases, localized injury, or the death of the organism of which the cells are part. Apoptosis or Type I cell-death, and autophagy or Type II cell-death are both forms of programmed cell death, while necrosis is a non-physiological process that occurs as a result of infection or injury. Programmed cell death Programmed cell death (PCD) is cell death mediated by an intracellular program. PCD is carried out in a regulated process, which usually confers advantage during an organism's life-cycle. For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result is that the digits separate. PCD serves fundamental functions during both plant and metazoa (multicellula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
