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Structure and properties of nucleic acid

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Structure and properties of nucleic acid

  1. 1. Submitted by: Deba prasad panda 10 PBG/14
  2. 2. Nucleic acid are long chain polymers of nucleotides present in nuclei of cell, so they are also called polynucleotide. They play an important role in transmission of hereditary characteristics and biosynthesis of proteins.  These are the largest and the most complex organic molecules.
  3. 3. Frederic Miesher a swiss scientist in 1869, isolated an acidic compound from the nuclear material of SALMON sperms, and named it as NUCLIEN which is now called NUCLEIC ACID.
  4. 4. NUCLEIC ACIDS  Nucleic acids are polymers  Monomer---nucleotides • Nitrogenous bases  Purines  Pyrimidines • Sugar  Ribose  Deoxyribose • Phosphates  +nucleoside=nucleotide }Nucleosides
  5. 5. Nucleic acid Nucleotides Phosphoric acid Nucleosides Sugar Ribose or deoxyribose Purine Guanine and Adenine Pyrimidine base Cytosine, uracil or thymine
  6. 6. The sugar in nucleotide, and so in nucleic acids , is a PENTOSE. In RNA and its nucleotide the sugar is RIBOSE, whereas in DNA and its nucleotide it is DEOXYRIBOSE. The prefix deoxy - means “without oxygen” . Nucleotides can be hydrolyzed to yield nucleosides and phosphoric acid.
  7. 7. The Sugars
  8. 8. 9 Two Kinds of Bases Pyrimidines are single ring bases. Purines are double ring bases. C C C C N N O N C C C C N N N N N C
  9. 9. BASES Purines: adenine, guanine (double ring) Pyrimidine: thymine, cytosine,uracil  (single rings)
  10. 10. 11 C C C C N N O N C C C C N N O N N N C Hydrogen Bonds  The bases attract each other because of hydrogen bonds.  Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA.  The bonds between cytosine and guanine are shown here with dotted lines
  11. 11. 12 Hydrogen Bonds, cont. When making hydrogen bonds, cytosine always pairs up with guanine Adenine always pairs up with thymine Adenine is bonded to thymine here C C C C N N O O C
  12. 12. Nucleosides
  13. 13. Nucleosides Pyrimidine Purine  Nucleoside: a compound that consists of D-ribose or 2-deoxy-D- ribose (monosaccharide) covalently bonded to a nucleobase by a -N-glycosidic bond  Covalent linkage forms between N9 of purines or N1 of pyrimidines to C1 (anomeric carbon of ribose or 2-deoxyribose)
  14. 14. Phosphate group Negatively charged at neutral pH Typically attached to 5’ position •Nucleic acids contain one phosphate per nucleotide
  15. 15. Monomers  nucleotides, are made up of three parts: (a) Phosphate (phosphoric acid) (b) N-base (Nitrogenous base) (c) Sugar ~ ribose or deoxyribose
  16. 16. Nucleotides Phosphat e Pentose Sugar Nitrogeno us Base
  17. 17. Polynucleotides
  18. 18. Nucleotide monomers are joined by 3’-5’ phosphodiester linkages to form nucleic acid (polynucleotide) polymers
  19. 19. Two types of nucleic acid are found Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) BY:- YOGESH MALANI
  20. 20. BY:- YOGESH MALANI
  21. 21. BY:- YOGESH MALANI
  22. 22.  DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix.  A molecule of DNA is made up of millions of tiny subunits called Nucleotides.
  23. 23. G G A T T A A C T G C A T C
  24. 24. • 1° structure: the order of bases on the polynucleotide sequence; the order of bases specifies the genetic code • 2° structure: the three-dimensional conformation of the polynucleotide backbone = double helix structure • 3° structure: supercoiling • 4° structure: interaction between DNA and proteins
  25. 25. DNA - 3° Structure
  26. 26. Four stranded form of DNA (quadruplex DNA) Role in regulating and stabilizing telomeres and in regulation of gene expression Small molecules such as porphyrins and anthraquinones present, to stabilize the structure
  27. 27. Structural features of A-, B-, and Z- DNA Type A-DNA B-DNA Z-DNA Helical sensesright handed right handed left handed Diameter (Å) ~26 ~20 ~18 Base pairs/turn 11 10 12 Major groove narrow/deep wide/deep Flat Minor groove wide/shallow narrow/deep narrow/deep
  28. 28. Properties of Nucleic Acids: • Nucleic acids are insoluble in alcohol, slightly soluble in cold water, but readily dissolved in hot water and dilute alkalies, forming alkali salts. They are precipitated by HCL and by excess of acetic acid. • Feulgen Test differentiates the DNA from RNA, if the deoxyribose sugar is present, a red color is produced with the dye. Ribose sugar do not exhibit this reaction. Hydrolysis of nucleic acids gives nucleotide, which can be considered the units that make up the polymer.
  29. 29. Biological Functions of Nucleic Acid  DNA is the chemical basis of heredity and may be regarded as the reserve of genetic information.  The proteins are synthesized by various RNA molecules in the cell but the message for the synthesis of a particular protein is present in DNA.  DNA is exclusively responsible for maintaining the identity of different species of organisms over millions of years.

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