Mathematics and computer science use artificial entities called formal languages (including programming languages and markup languages, and some that are more theoretical in nature). These often take the form of character strings, produced by a combination of formal grammar and semantics of arbitrary complexity.
Thursday, December 25, 2008
Monday, December 15, 2008
Polyadenylation
Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA molecule. In eukaryotic organisms, most messenger RNA (mRNA) molecules are polyadenylated at the 3' end. The poly(A) tail and the protein bound to it aid in protecting mRNA from degradation by exonucleases. Polyadenylation is also important for transcription termination, export of the mRNA from the nucleus, and translation. mRNA can also be polyadenylated in prokaryotic organisms, where poly(A) tails act to facilitate, rather than impede, exonucleolytic degradation.
Polyadenylation occurs during and immediately after transcription of DNA into RNA. After transcription has been terminated, the mRNA chain is cleaved through the action of an endonuclease complex associated with RNA polymerase. After the mRNA has been cleaved, around 250 adenosine residues are added to the free 3' end at the cleavage site. This reaction is catalyzed by polyadenylate polymerase. Just as in alternative splicing, there can be more than one polyadenylation variant of a mRNA.
Polyadenylation occurs during and immediately after transcription of DNA into RNA. After transcription has been terminated, the mRNA chain is cleaved through the action of an endonuclease complex associated with RNA polymerase. After the mRNA has been cleaved, around 250 adenosine residues are added to the free 3' end at the cleavage site. This reaction is catalyzed by polyadenylate polymerase. Just as in alternative splicing, there can be more than one polyadenylation variant of a mRNA.
Wednesday, December 03, 2008
Soy milk Health benefits
Soy milk is nutritionally close to cow's milk. It naturally has about the same amount of protein (though not the same amino acid profile) as cow's milk. Natural soy milk contains little digestible calcium as it is bound to the bean's pulp, which is insoluble in a human. To counter this, many manufacturers enrich their products with calcium carbonate available to human digestion. Unlike cow's milk it has little saturated fat and no cholesterol, which is a benefit. Soy products contain sucrose as the basic disaccharide, which breaks down into glucose and fructose. Since soy doesn't contain galactose, a product of lactose breakdown, it can safely replace breast milk in children with Galactosemia.
Soy milk is promoted as a healthy alternative to cow's milk for reasons including:
Soy milk is promoted as a healthy alternative to cow's milk for reasons including:
- Source of lecithin and vitamin E
- Lacks casein
- It is safe for people with lactose intolerance or milk allergy
- Polyunsaturated and monounsaturated fats are good for the heart. (It should be noted that whole milk has just as much monounsaturated fat as soy milk; and while it has less polyunsaturated, it contains the omega-3 fatty acids EPA and DHA that soy milk lack.)
- Contains isoflavones, organic chemicals that may possibly be beneficial to health.
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