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NUCLEIC ACIDS RNA and DNA Nucleic Acids A nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids are universal in living things, as they are found in all cells and viruses. Nucleic acids were first discovered by Friedrich Miescher. Nucleotide Nucleic acids consist of nucleotides that have a sugar, nitrogen base, and phosphate Nitrogen-Containing Bases Pentose (5 –Carbon) Sugars Deoxyribonucleotide Ribonucleotide ATP (Adensosine triphosphate) NAD+ + ATP -> NADP+ + ADP catalyzed by NAD+ kinase Polynucleotides DNA and RNA Structures Difference between DNA and RNA structures Characters DNA RNA 1. Molecule Double stranded, helical Single stranded, straight or variously folded and twisted. 2. Pentose sugar Deoxyribose Ribose 3. Pyrimidine base Thymine Uracil 4. Complementary base pairing Always present and Normally absent, but may exists between A = T and be present in twisted G=C segments of a molecule. If present, pairing is between A = U and G = C 5. Ratio of Purines: Always 1:1 Pyrimidines Not necessarily 1:1 Double-helical structure of DNA Double-helical structure of DNA DNA Replication Semiconservative Replication DNA Polymerization Plasmids A plasmid is an extrachromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA. In many cases, it is circular and doublestranded. Plasmids usually occur naturally in bacteria, but are sometimes found in eukaryotic organisms. Classification of RNA m- RNA Messenger or mRNA is a copy of the information carried by a gene on the DNA. The role of mRNA is to move the information contained in DNA to the translation machinery. t –RNA tRNA is the information adapter molecule. It is the direct interface between amino-acid sequence of a protein and the information in DNA. Therefore it decodes the information in DNA. There are > 20 different tRNA molecules. r-RNA Ribosomal RNA (rRNA) is the central component of the ribosome, the protein manufacturing machinery of all living cells. The function of the rRNA is to provide a mechanism for decoding mRNA into amino acids and to interact with the tRNAs during translation by providing peptidyl transferase activity. REFERENCES Michael L. Shuler and Fikret Kargı, Bioprocess Engineering: Basic Concepts (2 nd Edition),Prentice Hall, New York, 2002. 1. James E. Bailey and David F. Ollis, Biochemical Engineering Fundementals (2 nd Edition), McGraw-Hill, New York, 1986. www-ics.u-strasbg.fr www.msu.edu fig.cox.miami.edu student.ccbcmd.edu www.dvbiology.org nanobiologynotes.blogspot.com www.acmecompany.com http://www.diffen.com/difference/Dna_vs_Rna academic.brooklyn.cuny.edu faculty.uca.edu eapbiofield.wikispaces.com virtuallaboratory.net www.answers.com members.cox.net www.harunyahya.org www.wiley.com http://www.johnkyrk.com/DNAanatomy.html http://www.johnkyrk.com/DNAreplication.html http://207.207.4.198/pub/flash/26/transmenu_s.s wf
