Ribonucleic acid , functions

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell s genetic information. Coded in a cell s DNA is the information that determines the nature of the cell, controls the cell s growth and division, and directs biosynthesis of the enzymes and other proteins required for cellular functions. 

The storage of genetic information and the transcription and translation of this information are functions of the nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). They are polymers whose building blocks are nucleotides, which are themselves combinations of three parts, i.e. a heterocyclic base, a sugar, and phosphate (see Section 14.1). 

The nucleic acids play a central role in the storage and expression of genetic information (see p. 236). They are divided into two major classes deoxyribonucleic acid (DNA) functions solely in information storage, while ribonucleic acids (RNAs) are involved in most steps of gene expression and protein biosynthesis. All nucleic acids are made up from nucleotide components, which in turn consist of a base, a sugar, and a phosphate residue. DNA and RNA differ from one another in the type of the sugar and in one of the bases that they contain. 

The fluoropyrimidines as a group can affect the synthesis and function of both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), and both of these two mechanisms... 

Ostrowski NL, Lolait SJ, Bradley DJ, O Carroll AM, Brownstein MJ, Young WS (1992) Distribution of Via and V2 vasopressin receptor messenger ribonucleic acids in liver, kidney, pituitary and brain. Endocrinology 131 533-535 Otsuka M, Yoshioka K (1993) Neurotransmitter functions of mammalian tachykinins. Physiol Rev 73 229-308... 

All corticosteroids have the same general mechanism of action they traverse cell membranes and bind to a specific cytoplasmic receptor. The steroid-receptor complex translocates to the cell nucleus, where it attaches to nuclear binding sites and initiates synthesis of messenger ribonucleic acid (mRNA). The novel proteins that are formed may exert a variety of effects on cellular functions. The precise mechanisms whereby the corticosteroids exert their therapeutic benefit in asthma remain unclear, although the benefit is likely to be due to several actions rather than one specific action and is related to their ability to inhibit inflammatory processes. At the molecular level, corticosteroids regulate the transcription of a number of genes, including those for several cytokines. 

Transcription starts with the process hy which the genetic information is transcribed onto a form of RNA, called mRNA. Ribonucleic acid, RNA, is structurally similar to DNA with the exceptions that its nucleotides contain ribose, instead of a 2 -deoxyribose, and the base thymine is replaced by uracil. There are three major types of RNA depending on their specific functions. However, all three types of RNA are much smaller than DNA and they are single stranded, rather than double stranded. 

Biochemical analysis indicated that gene therapy completely restored ADA enzymatic function in PBLs and BM CD19+ -cells. Ptl also demonstrated vector ADA expression at the mitochondrial ribonucleic acid (mRNA) level in differentiated cells. Both patients demonstrated increased ADA activity in the plasma, and in Pt2, BM ADA activity was found to increase 8-fold after therapy. This increase in activity was correlated with a decline in... 

Ribonuclease is an enzyme with 124 amino acids. Its function is to cleave ribonucleic acid (RNA) into small fragments. A solution containing pure protein, with no other ions present except H+ and OH- derived from the protein and water, is said to be isoionic. From this point near pH 9.6 in the graph, the protein can be titrated with acid or base. Of the 124 amino acids, 16 can be protonated by acid and 20 can lose protons to added base. From the shape of the titration curve, it is possible to deduce the approximate pATa for each titratable group.1-2 This information provides insight into the environment of that amino acid in the protein. In ribonuclease, three tyrosine residues have "normal values of pATa(=10) (Table 10-1) and three others have pA a >12. The interpretation is that three tyrosine groups are accessible to OH, and three are buried inside the protein where they cannot be easily titrated. The solid line in the illustration is calculated from pA"a values for all titratable groups. 

A typical molecular analysis of various micro-organisms is shown in Table 5.9U ) Most of the elemental composition of cells is found in three basic types of materials—proteins, nucleic acids and lipids. In Table 5.10, the molecular composi-tion of a bacterium is shown in more detail. Water is the major component of the cell and accounts for 80-90 per cent of the total weight, whilst proteins form the next most abundant group of materials and these have both structural and functional properties. Most of the protein present will be in the form of enzymes. Nucleic acids are found in various forms—ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Their primary function is the storage, transmission and... 

The expression of the immediate early gene (IEG) c-fos has been extensively used as a functional marker of brain activity in neuroscience including sleep research (53-55). In most cell types, the basal level of c-fos expression is relatively low however, c-fos messenger ribonucleic acid (mRNA) and Fos protein can be rapidly and transiently induced by a diverse range of extracellular stimuli. Several laboratories have found that both c-Fos protein and mRNA levels decrease in the cerebral cortex during sleep relative to wakefulness (56-59). This decline has been linked to a reduction in the firing rate of the locus ceruleus during sleep and the consequent reduction of norepinephrine release in the cortex (60). 

Relatively recently Fe/S proteins have been found to function in the regulation of biosynthesis. This can be by promoting deoxyribonucleic acid (DNA) transcription, e.g. the [2Fe-2S] containing Escherichia coli superoxide-activated (SoxR) transcription activator [10-12], or the presumably [4Fe-4S]-containing E. coli transcription factor fumarate nitrate reduction (FNR) [13,14], Alternatively, the Fe/S protein can act by interference with messenger ribonucleic acid (mRNA) translation, i.e., the iron regulatory proteins (IRPs) [15,16], These interactions are stoichiometric, therefore not catalytic. Presumably, they are also a form of sensoring, namely, of oxidants and/or iron [17],... 

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