Nucleic Acids Are The Organic Compounds

Nucleic Acids Are The Organic CompoundsNucleic stiflings were discovered by Friedrich Miescher, a Swiss biochemist, in 1869. He c whollyed them nucleic because he believed that they occurred only in the nucleus of the electric cell 1.Nucleic Acids are the organic compounds found in the chromo well-nighs of living cells and in viruses. The structure of the nucleic acids in a cell determines the structure of the proteins produced in that cell. Since proteins are the building blocks of life, nucleic acids can be considered the blueprints of life. But chemically we can define nucleic acids as pinchs that are comprised of monomers k in a flashn as nucleotides.2,3The two all important(p) compositors baptismal fonts of nucleic acids are-Deoxyribonucleic acid ( deoxyribonucleic acid) -It ordinarily occurs only in the cell nucleus.Ribonucleic acid ( ribonucleic acid)-It is found both in the nucleus and in the cytoplasm (the main part of the cell exclusive of the nucleus).Both DNA and ribonucleic acid combine with protein materials to carry out cell division and cell repair processes. 4Deoxyribonucleic acid ( DNA)A type of nucleic acid that constitutes the molecular basis of heredity. It is found principally in the nucleus of all cells where it radiation diagrams part of the chromosome, or in the cytoplasm of cells lacking a nucleus, such as bacteria. It acts as the carrier of genetic t separatelying containing the instructions (code) to dumbfound proteins. It consists of two single chains of nucleotides, which are twisted round each(prenominal) some other to form a parlay ringlet or spiral. The nucleotides contain sugar (deoxyribose), orthophosphate and the bases (adenine, light speed, guanine and thymine). The two strands of DNA are held together by hydrogenbonds located between specific pairs of bases (adenine to thymine and cytosine to guanine). The succession of bases and consequently gene sequence is sometimes altered, causing mutation. DNA includ es the sugar deoxyribose, which has one less(prenominal) oxygen atom than ribose the sugar found in ribonucleic acid, hence the name is deoxy-ribose nucleic acid.6,7Each DNA molecule is a long two-stranded chain. The strands are made up of subunits called nucleotides, each containing a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases, adenine, guanine, thymine, and cytosine, denoted A, G, T, and C, respectively. A given strand contains nucleotides bearing each of these four. The reading carried by a given gene is coded in the sequence in which the nucleotides bearing unlike bases a soccur along the strand.The chemical and physical properties of DNA suit it for both replication and point of information . anatomy 1.A 3D rendered computer model of the DNA double helix. 16body structure Of DNAIts structure, with two strands wound well-nigh each other in a double helix to resemble a twisted ladder, was first set forth (1953) by Francis Crick and James D. Watso n and they named it as Watson and Crick model of DNA which states thatFig 2. Double helix structure of DNAIt is a double helix with two powerful handed coiling polydeoxy ribonucleotide strands twisted around the same central axis.The two strands are anti parallel. The phosphodiester linkages of one of these strands run in 5 to 3 direction while the other strand runs in 3 to 5 direction. The bases are stacked within the helix in planes perpendicular to the helical axis.These two strands are held together by hydrogen bonds. In addition to hydrogen bonds, other forces e.g., hydrophobic interactions between stacked bases are similarly responsible for constancy and maintenance of double helix.Adenine forever pairs with thymine while guanine always pairs with cytosine.A-T pair has 2 hydrogen bonds while G-C pair has 3 hydrogen bonds. Hence, G C is more stronger than A=T.The issue of adenine is equal to the content of thymine and the content of guanine is equal to the content of cyto sine. This is Chargaffs rule, which is proved by the complementary base pairing in DNA structure.The genetic information is present only on one strand known as template strand.The double helix structure contains major and nestling grooves in which proteins interact with DNA.The diameter of double helix is 2nm. The double helical structure repeats at intervals of 3.4 nm (one completer turn) which corresponds to 10 base pairs.7,8,9Different forms of DNADouble helical structure exists in six different forms. They are A-DNA, B-DNA, C-DNA, D-DNA, E-DNA and Z-DNA. Among these only 3 forms of DNA are important. They are B-DNA, A-DNA and Z-DNA.5.1 B-DNA-This is nothing but the double helical structure described by Watson and Crick. It has 10 base pairs in each turn.5.2 A-DNA-This is also a right handed helix. It has 11 base pairs per turn.5.3 Z-DNA-This is a left handed helix. It has 12 base pairs per turn. The strands in this form move in a zig-zag manner and hence it is called as Z-DNA.1 2,13Properties of DNAThe properties shown by DNA that allows for contagious disease of genetic information to new cells are as follows-ReplicationTranscriptionTranslation6.1 ReplicationAn important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the emeritus cell.Fig3. Replication Process in DNA 306.2 TranscriptionTranscription is the process in which DNA nucleic acids transfer the cells genetic information into ribonucleic acid materials. In essence, each DNA strand manufactures a corresponding RNA strand. Three types of RNA are manufactured within this process. 13Messenger RNAs (mRNA) are designed to carry the genetic information received from the DNA strands. Ribosomal RNAs (rRNA) reside in the cells cytoplasm, and areresponsible for decoding, or transla ting the genetic instructions into cell processes. Transfer RNAs ( acceptor RNA) are responsible for gathering whatever amino acids are needed for protein synthesis.14Fig4. Transcription In DNA 206.3 TranslationTranslation is the process in which RNA molecules create the proteins needed to sustain incumbent cell functions. This is accomplished by converting the genetic code contained in the messenger RNAs into amino acid strings, which is what make protein molecules. This conversion process set outs step forward within the ribosomes, which are located in the cells cytoplasm. 14Functions of DNA (deoxyribonucleic acid)DNA is a permanent storage place for genetic information.DNA controls the synthesis of RNA (ribonucleic acid).The sequence of nitrogenous bases in DNA determines the protein development in new cells.The function of the double helix formation of DNA is to guarantee that no disorders occur. This is because the second identical strand of DNA that runs anti-parallel to t he first is a backup in case of lost or destroyed genetic information. Ex. Downs Syndrome or Sickle Cell Anemia.16,17RNA( ribonucleic acid)It is another type of nucleic acid which functions in cellular protein synthesis in all living cells. They play an essential employment in the synthesis of proteins. On hydrolysis they yield the pentose sugar ribose, the purine bases adenine and guanine, the pyrimidine bases cytosine and uracil, and phosphoric acid.RNA occurs mostly in the cytoplasm in the eukaryotic cells. A small amount occurs in the nucleus of the cell, as a fortune of nucleolus. RNA is a single polynucleotide chain composed of nucleotides of adenine, guanine, cytosine and uracil. Thymine nucleotides are absent.Structure of RNARiboNucleic Acids consist ofRibose (a pentose = sugar with 5 vitamin Cs)Phosphoric AcidOrganic (nitrogenous) bases Purines (Adenine and Guanine) and Pyrimidines (Cytosine and Uracil)An RNA molecule is a one-dimensional polymer in which the monomers ( nucleotides) are linked together by means of phosphodiester bridges, or bonds. These bonds link the 3 carbon in the ribose of one nucleotide to the 5 carbon in the ribose of the adjacent nucleotide.Fig 5. Chemical Structure of RNA 19Purines Adenine A Guanine G Pyrimidines Uracil U Cytosine C Fig 6. Organic Bases Structure of RNA 21 morphological Difference between RNA and DNARNA differs, however, from DNA because it does not form an analogous double helical structure. The pyrimidine base thymine is modified in that it lacks a methyl group and the resulting uracil takes its place in base pairing. Together, the presence of uracil in place of thymine, and the 2-OH in the ribose constitute the two chemical differences between RNA and DNA which is shown in Fig 7.Fig7. Structural difference between RNA and DNA 19Types Of RNA11.1 Messenger RNA (mRNA)It represents active 5 to 10% of the total RNA. It is synthesised from DNA as and when necessary. It carries the genetic information in the f orm of a specific sequence of nitrogen bases arranged in triplet codons, which are copies from the code in DNA.11.2 Transfer RNA (tRNA)It represents about 10 to 15% of the total RNA in the cell. It has the shortest molecule having only about 80 to cytosine nucleotides. The polynucleotide chain is folded on itself to have the shape of a cloverleaf. The molecule has three lateral loops, a DHU loop, a t loop and an anticodon loop. The anticodon loop bears a triplet combination of nitrogen bases, called anticodon. It is complementary to a codon of mRNA.The tRNA molecule is meant for recognising and carrying particular types of amino acids to the sites of protein synthesis.11.3 Ribosomal RNA (rRNA)It represents nearly 80% of the total RNA in the cell. It always occurs bound to basic proteins in ribosomes. It takes part in assembling the amino acids brought by tRNA, into a polypeptide chain, establish on the sequence of codons in mRNA. 19,20Functions of RNARNA serves the following functi onsmRNA has a significant role in genetic code.tRNA is responsible for transferring amino acids to the site of protein synthesis (ribosomes).rRNA assembles the amino acids into a polypeptide chain. It also serves as a primer for replication of DNA.RNA serves as the genetic material in some plant viruses. 21Applications of Nucleic AcidNucleic acids find a number of exciting applications in various fields. .13.1 Microarrays and biosensorsPNA(peptide nucleic acid) can be used on microarrays and other biosensors. PNA microarray combined with PCR could detect genetically modified organisms (GMOs) in food13.2 visualize probes and FISHPNA is especially good for FISH because it can bind to DNA or RNA quickly even under low salt or other unfavorable conditions for DNA.PNA s specificity was utilized to fork 16S rRNA of bacteria species in drinking water. PNA probes also have been used for in vivo imaging of mRNA for crabby person research. 2313.3 Catalysts and receptorsNucleic acids can al so be employed as enzymes (for catalysis) and receptors (for ligand binding). Increasingly, researchers are making interesting use of these molecules, now collectively called functional nucleic acids.13.4 Body functionsEssential bodily functions such as growth, repair and reproduction all avow on nucleic acid for direction and support. Nucleic acid is in nearly every cell of the body. 2413.5 medicative UsesGen-Probe Inc. (San Diego, California) introduced nucleic acid probe-based diagnostic products for gonorrhea and chlamydia. It is a direct test based on DNA ribosomal RNA hybridization, with demonstrated sensitivity of 89.9% to 97.1%, and specificity of 93% to 98%. 23, 26FUTURE PROSPECTS OF NUCLEIC ACIDNucleic-acid-amplification test (NAAT) is used for the diagnosis of TB(tuberculosis) by the new method instead of conventional smear/culture method. So NAAT will simply take us to a new era of advanced, effective, and fast TB diagnosis.Attempts are done to employ nucleic acids in effective gene therapy which is believe to become commonplace in recent years.At the same time, however, the hit the books of nucleic acids has revealed remarkable properties of DNA and RNA molecules that could make them attractive therapeutic agents, independent of their well-known ability to convert biologically active proteins. Infuture we will find alternative uses of nucleic acids that do not rely on virus-based vectors or even on gene transfer.Tuberculosis (TB) is an important target for clinical testing due to the increase in incidence of the disease in this decade. Both Roche and Gen-Probe,great are developing kits for rapid TB testing. The Roche kit is based on PCR technology, while Gen-Probes kit uses transcription mediated amplification. 27, 28, 29