The Functions of DNA

DNA occurs almost exclusively in the eukaryotic (nonbacterial, notably mammalian) cell nucleus, whereas RNA is located in the surrounding region, what is called the cytosol or cytoplasm (Voet and Voet, 1995, pp. 8, 918). The cytosolic RNA-contain-ing particles are protein rich, and are known as ribosomes. 

The polymerization of nucleotides to form DNA and RNA is catalyzed by various enzymes called nucleases, which serve in a selective manner (Aktipis, in Devlin, 1986, p. 802). Generally known as DNases and RNases, listings of various kinds with inhibitors are presented in Appendix E and F of Hoffman (1999a). 

There is a constant turnover of protein nucleic acids, signifying both synthesis and degradation (Cory, in Devlin, 1986, pp. 659,660). Synthesis is in part dependent on the enzyme deoxyuridine triphosphatase (dUTPase), and the Cory reference notes that dUTPase may in fact be a factor in cancer proliferation. 

A DNA macromolecule is able to store or encode an enormous quantity of genetic information by virtue of its extensive polynucleotide structure (Aktipis, in Devlin, 1986, p. 798ff). The analogy is to proteins, which are made up of a chain of amino acids joined by what are called peptide bonds, to yield the polymer or macromolecule. Thus, there is a similarity between the structures of polynucleotides and proteins, which is a factor in transmitting genetic information between the DNA and protein macromolecules, with RNA serving as the medium or intermediate. 

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Avery s studies shed light on the function of DNA. Chargaff s touched on structure in that knowing the distribution of A, T, G, and C in DNA is analogous to knowing the fflnino acid composition of a protein, but not its sequence or three-dimensional shape. 

It would not be too far fetched to state that life on this planet is totally dependent on two compounds based on the purine nucleus. Two of the bases crucial to the function of DNA and flNA—guanine and adenine—are in fact substituted purines. It is thus paradoxical that the lead for the development of medicinal agents based on this nucleus actually came from observations of the biologic activity of plant alkaloids containing that heterocyclic system, rather than from basic biochemistry. 

What Crick called the "central dogma of molecular genetics" says that the function of DNA is to store information and pass it on to RNA. The function of... 

The functions of DNA—coding for its own synthesis and for the synthesis of mRNA, tRNA, and rRNA—can be disrupted by altering, one way or another, DNA structure. There are two general ways to do this first, by reacting chemically with DNA and, second, by intercalating between the stacked bases of DNA. Let s have a short look at both possibilities. 

To take a step closer to defining the function of DNA sequences, the sequences are fluorescence tagged to identify transcriptional activity of genes (but not translation of protein), which then can be related to the disease state or medication. This information allows researchers to hunt for genes that are affected in disease states (e.g., mutation in CFTR gene regulating a chloride channel in cystic fibrosis patients)... 

The same studies were performed with calf thymus DNA. In addition to the absorption and emission spectra, we have recorded the fluorescence excitation spectra of ethidium bromide at different DNA concentrations (Figure 12.12). One can see that the increase in fluorescence intensity stops when the stoichiometry of the complex is reached. Binding parameters (n = 2.6 and Krl = 3 x 105 M-1) determined from the fluorescence excitation intensities are found to be equal to those calculated with the fluorescence emission and the OD variations. Figure 12.13 shows the normalized intensity increase in both fluorescence emission and excitation intensity peaks of ethidium bromide with the function of DNA. The intensity increase in the excitation spectrum of ethidium bromide in the presence of DNA is the result of binding of the fluorophore to DNA and thus of the increase in the number of excited bound fluorophores. 

It is likely that cells utilize the physico-chemical properties inherent in genomic DNA molecules, which are highly charged, locally stiff, and very long in the course of their functioning. Unveiling the higher-order structure and its relation with the function of DNA and chromatin is awaited. 

The function of DNA Watson and Crick used their model to predict how DNA s chemical structure enables it to carry out its function. DNA stores the genetic information of a cell in the cell s nucleus. Before the cell divides, the DNA is copied so that the new generation of cells gets the same... 

Azathioprine/6-MP are a source of thioguanine nucleotides, which incorporate into DNA, yielding abnormal DNA that, in turn, interferes with the function of DNA polymerases, ligases, and endonucleases. 

In this chapter we discuss the structure and properties of DNA. Subsequent chapters examine the functions of DNA... 

Methyl groups can be added to bases in DNA. Except for some yeasts and insects, all DNA contains methylated bases. The attachment of methyl groups to bases at specific sequences in DNA acts to regulate the functions of DNA. One function of site-specific methylation in prokaryotes is to protect endogenous bacterial DNA from digestion by restriction endonucleases produced by the bacteria. 

Dery, U., and Masson, J. Y. (2007). Twists and turns in the function of DNA signalhng and repair proteins by post-translational modifications. 

There are many examples of 2H lineshape analyses in the review period, but one of particular interest is the work by Drobny et al.37 This study examines the conformational flexibility of the furanose ring, which is of particular importance in the functioning of DNA. They examined the nucleoside [2 -2H]-2 -deoxycytidine deuterated at the C3 position (Fig. 26(a)) and contained in the sequence [d(CGCGAATTCGCG)]2. The furanose ring... 

Metal cations are present in aqueous solution, and are often complexed to anionic biomolecules. For example, Mg is essential for the function of DNA and for the synthesis and utilization of ATP. Special ion pumps maintain much lower concentrations of Na and Ca within cells than in extracellular fluids, and local changes in the concentrations of these two cations are used for signaling. The passage of nerve signals is associated with an influx of Na. Ca forms complexes with carboxylate groups and acts to alter the conformation of many macromolecules in particular this ion plays a role in muscle contraction. 

From there, emphasis has become more and more focused on the function of DNA in heredity, the process in space and time by which DNA duplicates itself (3D—ft) and controls the protein syntheses and metabolic processes that determine the inheritance of characteristics from parents to offspring. 

What difference between RNA and DNA helps to explain the greater stability of DNA What Implications does this have for the function of DNA ... 

The mysterious behaviour of bio-macromolecules is one of the outstanding problems of molecular biology. The folding of proteins and the replication of DNA transcend all classical mechanisms. At this stage, non-local interaction within such holistic molecules appears as the only reasonable explanation of these phenomena. It is important to note that, whereas proteins are made up of many partially holistic amino-acid units, DNA consists of essentially two complementary strands. Nonlocal interaction in DNA is therefore seen as more prominent, than for proteins. Non-local effects in proteins are sufficient to ensure concerted response to the polarity and pH of suspension media, and hence to direct tertiary folding. The induced fit of substrates to catalytic enzymes could be promoted in the same way. Future analysis of enzyme catalysis, allosteric effects and protein folding should therefore be, more ambitiously, based on an understanding of molecular shape as a quantum potential response. The function of DNA depends even more critically on non-local effects. 

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