5 nucleotides and nucleic acids lecture

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5 nucleotides and nucleic acids lecture

  1. 1. Principle of Biochemistry5-Nucleotides and Nucleic Acids Course code: HFB324 Credit hours: 3 hours Dr Siham Gritly Dr Siham Gritly 1
  2. 2. Nucleoside, Nucleotide & Nucleic acid p h o s p h a te su g a r base p h o s p h a te p h o s p h a tesu g a r base su g a r base su g a r base p h o sp h a te nucleoside nucleotides sugar b a se nucleic acids Dr Siham Gritly 2
  3. 3. DNA, RNA and the nucleobases Dr Siham Gritly 3
  4. 4. • Deoxyribonucleotide; monomeric building block of DNA; a phosphate group and a nitrogenous base both bonded to deoxyribose• Ribonucleotide; monomeric building block of RNA; a phosphate group and a nitrogenous base both bonded to ribose sugar• Duplex; two complementary strands of DNA• Mutant; genetically altered species or cell Dr Siham Gritly 4
  5. 5. • Nucleoside; nitrogenous base bonded to ribose or deoxyribose• Nucleotide; monomeric building block of RNA and DNA; a phosphate group and a nitrogenous base both bonded to ribose or deoxyribose• Nucleic Acids are Polynucleotides• Phosphodiester; two different alcohols forming ester linkages with one phosphate ion Dr Siham Gritly 5
  6. 6. • Replication; DNA synthesis• Template; a section of DNA which is being replicated or transcribed; mRNA which is being translated• Transcription; synthesis of RNA from DNA• Translation; synthesis of proteins from an RNA template Dr Siham Gritly 6
  7. 7. Nucleotides and Nucleic Acids• Introduction;• Nucleic acids are macromolecules present in all living cells in combination with protein with high concentration of basic amino acids to form nucleoproteins. (protamines and histones)• Nucleic acids compounds carrying information -- the genetic molecules (DNA and RNA) . Dr Siham Gritly 7
  8. 8. • The nucleic acids are of two types• -1-deoxyribonucleic acid DNA• -2-ribonucleic acid RNA• DNA is present in the nuclei small amounts present in the mitochondria• RNA is present in the cell cytoplasm (90%) about 10% present in the nucleolus Dr Siham Gritly 8
  9. 9. Nucleotides Nucleoside phosphates• Nucleotides are monomers of nucleic acids• The nucleotides found in cells are derivatives of the heterocyclic highly basic, compounds, purine and pyrimidine present in DNA and RNA (nitrogenous bases) Heterocyclic are ring compounds that contain both carbon atom and non-carbon atoms -- mainly nitrogen atom. Dr Siham Gritly 9
  10. 10. Nucleotide Structures of purine and pyrimidine Heterocyclic ring compounds Nitrogenous BasesSingle six-sided ring Double ring purinespyrimidinesC4H4N2 (six- and five-sided) C5H4N4 Dr Siham Gritly 10
  11. 11. Types of nucleotide bases• There are five major bases found in cells.• The derivatives of purine are called adenine and guanine (found in both DNA & RNA) ,• the derivatives of pyrimidine are called thymine, cytosine and uracil.• Dr Siham Gritly 11
  12. 12. The derivatives of purine ; adenine and guanine (found in bothDNA & RNA) 1-Adenine 6-aminopurine, 2-Guanine 2-amino-6-oxypurine Dr Siham Gritly 12
  13. 13. the derivatives of pyrimidine are thymine, cytosine and uracil.Cytosine- 2-oxy-4-aminopyrimidine, Uracil-n2,4-dioxypyrimidineThymine-2,4-dioxy-, 5-methyl Dr Siham Gritly 13
  14. 14. • The common abbreviations used for these five bases are, A, G, T, C and U.• Cytosine & Uracil in RNA• Cytosine and thymine in DNA• The nucleotide uridine is never found in DNA• thymine is almost exclusively found in DNA.• Thymine is found in tRNAs but not rRNAs nor mRNAs Dr Siham Gritly 14
  15. 15. Nucleotides mainly; Pentose sugar+ β-N-glycosidic bond+ phosphoryl group• Derivative of purines and pyrimidines are nucleotides----contain mainly cyclyized sugar Pentose linked to nitrogen hetroatom by β-N- glycosidic bond additional to phosphoryl group esterified to hydroxy group of the sugar (β-D-ribose or β-D-2-deoxyribose) Dr Siham Gritly 15
  16. 16. Nucleotides mainly; 1-pentose sugar. 2-phosphate groups. 3-a nitrogeous base• 1-5–carbon sugar component• Ribose• Deoxyribose Dr Siham Gritly 16
  17. 17. 5–carbon sugar component; Ribose and Deoxyribose Furanose structures Dr Siham Gritly 17
  18. 18. • 2-Phosphate group Attached to the sugars 5 carbon with a phosphodiester bond• 3-Nitrogen Base component attached to the sugars 1carbon. Dr Siham Gritly 18
  19. 19. Functions of Nucleotides• Components of nucleic acids (which are long chains of nucleotides)• ATP (Adonosine TriPhosphate) is central to energy metabolism• GTP (Guanosine TriPhosphate) drives protein synthesis• CTP (Cytidine Triphosphate) drives lipid synthesis• UTP (Uridine Triphosphate) drives carbohydrate metabolism Dr Siham Gritly 19
  20. 20. • Energy transport coenzymes (NAD+, NADP+, FAD+)• Chemical intracellular messengers (e.g., Cyclic AMP, a cyclic nucleotide that carries messages from the cell membrane to molecules within the cell, to stimulate essential reactions. regulators of cellular metabolism and reproduction ) Dr Siham Gritly 20
  21. 21. Nucleosides• Nucleoside consist of purine and pyrimidine bases and a sugar β-D-ribose or β-D-2- deoxyribose linked through a covalent β-N- glycosidic bond• Therefore Nucleosides are Formed by Joining a Nitrogenous Base to a Sugar• Base is linked via a β-N-glycosidic bond Dr Siham Gritly 21
  22. 22. β-N-glycosidic bond linked nitrogen-9 of the purine base or nitrogen-1 of the pyrinidine base with carbon1 of pentose sugar Dr Siham Gritly 22
  23. 23. • The nucleosides of A, G, C,T, U are named• Adenine ---Adenosine• Guanine ----Guanisine• Cytosine ----Cytidine• Thymine ----Thymidine• Uracil -----Uridine• Purine nucleosides end “osine”• Pyrinidine ends in “idine”• Ribose sugar produced; ribonucleoside• 2-deoxyribose sugar produced; deoxyribonucleosides Dr Siham Gritly 23
  24. 24. • The nucleosides in DNA are called; deoxyadenosine,• deoxyguanosine,• deoxycytidine, and thymidine,• the nucleosides in RNA are called;• adenosine, guanosine, cytidine, and uridine.• If the base is a purine, then the N-9 (nitrogen) is bonded to the C-1 (carbon) of the sugar.• If the base is a pyrimidine, then the N-1 is bonded to the C-1 of the sugar. Dr Siham Gritly 24
  25. 25. Common nucleosides Dr Siham Gritly 25
  26. 26. Glycosidic Bond Configurations Dr Siham Gritly 26
  27. 27. The base can exist in 2 distinct orientations about theN-glycosidic bond. These conformations are identified as, syn and anti. It is the anti conformation that predominates in naturally occurring nucleotides Syn- adenosine anti-adenosine Dr Siham Gritly 27
  28. 28. Nucleotides and nucleosides that are not part of DNA or RNA the importance of free nucleotide• Some nucleotides are not part of DNA or RNA but still play important roles in a cell.• cyclic adenosine monophosphate (cAMP) is an intracellular signal: it communicates information from one part of the cell to another.• Other nucleotides are coenzymes, which are molecules that help enzymes work properly (FAD, NAD). Dr Siham Gritly 28
  29. 29. Adenosine triphosphate (ATP)Adenosine triphosphate (ATP) is a commonand critical energy transfer molecule. Thebonds that hold three phosphate groups toadenosine store energy. They form whenenergy is released and transfer that energy toother places in a cell. Dr Siham Gritly 29
  30. 30. Adenosine Monophosphates (AMP) Dr Siham Gritly 30
  31. 31. Nucleic acid polynucletide• the nucleic acids are polymers of subunits of monomers nucleotides.• Nucleic acid; important substance that all cellular organisms use to store their genetic information.• The most common nucleic acids are deoxyribonucleic acid and ribonucleic acids Dr Siham Gritly 31
  32. 32. The chemical linkage between nucleotide units in nucleic acids is aphosphodiester, which connects the 5’-hydroxyl group of one nucleotide to the 3’-hydroxyl group of the next nucleotide.• Phosphodiester bonds are essential to all life, as they make up the backbone of each helical strand of DNA.• In DNA and RNA, the phosphodiester bond is the linkage between the 3’ carbon atom of one sugar molecule and the 5’ catbon atom of another;• the sugar molecules deoxyribose in DNA• and ribose in RNA.• Hydrolysis of phosphodiester bonds can be catalyzed by the action of phosphodiesterases Dr Siham Gritly 32
  33. 33. Sequences of RNA and DNA structuresThe chemical linkage between monomer units in nucleic acids is a phosphodiester Dr Siham Gritly 33
  34. 34. phosphodiester, connects the 5’-hydroxyl group of onenucleotide to the 3’-hydroxyl group of the nextnucleotide. Dr Siham Gritly 34
  35. 35. Formation of phosphodiester bondsFormed by Polymerase and Ligase activities Dr Siham Gritly 35
  36. 36. classes of nucleic acids1-Deoxyribonucleic acid DNA• Deoxyribonucleic acid (DNA) is anucleic acid containing the genetic instructions used in the development and functioning of all known living organisms (with the exception of RNA viruses).• The DNA segments carrying this genetic information are called genes .• Genes (specific regions of DNA molecules) contain the hereditary information of an organism. Dr Siham Gritly 36
  37. 37. • When organisms reproduce The code is read by copying stretches of DNA into the related nucleic acid RNA in a process called transcription.• Within cells DNA is organized into long structures called chromosomes, (packaged form of the DNA).• During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes (46).• Within the chromosomes, chromatin proteins such as histones compact and organize DNA. Dr Siham Gritly 37
  38. 38. DNA structure and function• DNA structure is the well-known double helix formed by Watson-Crick base-pairing of C with G and A with T.• This is known as B-form DNA, and is the most favorable and common state of DNA;• its highly specific and stable base-pairing is the basis of reliable genetic information storage. Dr Siham Gritly 38
  39. 39. Structure of DNAnaturally occurring DNA molecules are double- stranded Watson-Crick model for the structure of DNA Dr Siham Gritly 39
  40. 40. Tertiary Structure of DNA: Supercoils. Each cellcontains about two meters of DNA. DNA is “packaged”by coiling around a core of proteins known as histones.The DNA-histone assembly is called a nucleosome.Histones are rich is lysine and arginine residues Dr Siham Gritly 40
  41. 41. the Watson-Crick model• James Watson and Francis Crick proposed a model for the structure of DNA.• This model predicted that DNA would exist as a helix of two complementary antiparallel strands, wound around each other in a rightward direction and stabilized by H- bonding between bases in adjacent strands. Dr Siham Gritly 41
  42. 42. • They proposed that in any given molecule of DNA,;-• the concentration of adenine (A) is equal to thymine (T)• and the concentration of cytidine (C) is equal to guanine (G).• This means that A will only base-pair with T, and C with G. According to this pattern, known as Watson-Crick base-pairing, the base-pairs composed of G and C contain three H-bonds, whereas those of A and T contain two H-bonds. This makes G-C base-pairs more stable than A-T base-pairs. Dr Siham Gritly 42
  43. 43. Base pairing model Dr Siham Gritly 43
  44. 44. Base pairs are stabilized by H-bonding Dr Siham Gritly 44
  45. 45. the base-pairs composed of G and C contain three H-bonds, whereas those of A and T contain two H-bonds. Dr Siham Gritly 45
  46. 46. Watson-Crick base-pairing of C with G and A with T Dr Siham Gritly 46
  47. 47. Complementarity of strands in the DNA double helix -Adenine (A) and thymine (T) always pair together (A–T), -cytosine (C) and guanine (G) always pair together (C–G). In other words, A and T are complementary bases, as are C and G. Dr Siham Gritly 47
  48. 48. Replication of DNA as suggested by Watson and CrickReplication: processby which DNA iscopied itself Dr Siham Gritly 48
  49. 49. Two polynucleotide strands, running in opposite directions(anti-parallel) and coiled around each other in a double helix.The strands are held together by complementary hydrogen-bonding between specific pairs of bases Dr Siham Gritly 49
  50. 50. REPLICTION, TRANSCRIPTION AND TRANSLATION Dr Siham Gritly 50
  51. 51. Function of DNA• 1-store of genetic information;• genetic information is the source of information for the synthesis of all protein molecules. The information is copied or transcribed into RNA molecules• Proteins are then synthesized in the process involving the translation of the RNA Dr Siham Gritly 51
  52. 52. • 2-DNA provides the inherited information by the daughter cell. DNA provide template for the replication of information into daughter DNA molecule Dr Siham Gritly 52
  53. 53. 2-Ribonucleic acid RNA• Ribonucleic acid RNA is a long unbranched macromolecules consisting of nucleotides joined by 3’ to 5’ phosphodiester bonds. It is the same as DNA but it possesses different characteristic• RNA differ from DNA in that it is a single strand do not contain regions of double helical structure Dr Siham Gritly 53
  54. 54. • RNA contain ribose sugar instead of 2- deoxyribose that present in DNA• contain four major bases• 1-purine bases;-Adenine and Guanine• 2-pyrimidin bases;- Cytosine and Uracil• RNA contain Uracil instead of thymine• RNA pairs Adenine with Uracil and Cytosine with Guanine Dr Siham Gritly 54
  55. 55. Structure of RNARNA molecules are single-stranded RNA contain Uracil instead of thymine RNA pairs Adenine with Uracil and Cytosine with Guanine Dr Siham Gritly 55
  56. 56. Ribonucleic acid (RNA) functions• Ribonucleic acid (RNA) functions in converting genetic information from genes into the amino acid sequences of proteins. RNA translates the DNA message to a format that can be read by ribosomes, or the cellular organelles that assemble proteins (process known as translation). RNA also plays a role in engage the correct amino acids to the protein meeting sites. Dr Siham Gritly 56
  57. 57. types of RNA• The three universal types of RNA include• 1-transfer RNA (tRNA), transfer RNA serves as the carrier molecule for amino acids to be used in protein synthesis, and is responsible for decoding the mRNA.• 2-messenger RNA (mRNA), messenger RNA acts to carry genetic sequence information between DNA and ribosomes, directing protein synthesis• 3-ribosomal RNA (rRNA). ribosomal RNA is a major component of the ribosome, and catalyzes peptide bond formation. Dr Siham Gritly 57
  58. 58. RNA & DNA structures Dr Siham Gritly 58
  59. 59. PHOSPHODIESTER BOND LINK NUCLETIDES Dr Siham Gritly 59
  60. 60. referencesMurry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell W. Victor (1999). Harpers Biochemistry. Appleton and Lange , twent fifth edition• A. Burtis, Edward R. Ashwood, Norbert W. Tietz (2000), Tietz fundamentals of clinical chemistry• Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59 Dr Siham Gritly 60
  61. 61. references• Nelson DL, Cox MM (2005). Lehningers Principles of Biochemistry (4th ed.). New York, New York: W. H. Freeman and Company.• Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings.• Naik Pankaja (2010). Biochemistry. 3ed edition, JAYPEE• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 139. ISBN 0-393- 97378-6. Dr Siham Gritly 61
  62. 62. Pentose sugar Dr Siham Gritly 62
  63. 63. Dr Siham Gritly 63
  64. 64. Dr Siham Gritly 64
  65. 65. Dr Siham Gritly 65

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