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4-Nucleic Acids.ppt

  2. Nucleic Acids • These are biomolecules which consist of one or two ring of nitrogenous base, either purine or pyrimidine derivatives, a five carbon sugar (pentose sugar) and one or more phosphate groups
  4. Mitochondria DNA (mtDNA)
  5. Myths of DNA Fibonacci sequences – 0,1,1,2,3,5,8,13.21,34,55,89…. Golden Ratio Φ = 1.61803 Leonardo Bonacci aka Fibonacci
  6. • Nucleic acids are polymers of nucleotides that occurring in all living systems • Nucleic acids are the chemical carriers of an organism’s genetic information which play a great role functions in a living system • Store and transmit genetic information • Translation of genetic information • Nucleotide participates in almost all biochemical processes and is the one of the most important metabolites of the cell Nucleic Acids
  7. Understanding Nucleic Acids •Nucleic acids are the chemical carriers of an organism’s genetic information (DNA & RNA) •Nucleic acids are polymers of nucleotides •They store, transmit and translation of genetic information •Composed with Sugar, base and Phosphate group
  8. 14 Nucleotides and Nucleoside • Building blocks of nucleic acids - Sugar + Base = Nucleoside - Nucleoside + Phosphate = Nucleotide ▲ Nucleotides are monophosphate esters of nucleosides
  9. 15 Structure of nucleic acid Nucleic Acid has 3 components: (i) Pentose sugar (ii) Nitrogenous base & (iii) Phosphate group (i) Pentose sugar
  10. 16 (ii) Nitrogenous base Either from purine or pyrimidine derivatives - Purine: Adenine (A) and Guanine (G) - Pyrimidine : Thymine (T), Cytosine (C) & Urasil (U) Purine Pyrimidine
  11. 17 • Purine derivatives bases
  12. 18 • Pyrimidine derivative bases
  13. 19 (iii) Phosphate group • The most common site of phosphorylation of nucleotides found in cells is the hydroxyl group attached to the 5'- carbon of the ribose.
  14. 20 Polynucleotides • There two types of polynucleotides: DNA and RNA • Deoxyribose-containing nucleotide, deoxyribonucleotides, are the monomers of DNA and • Ribose-containing nucleotides, ribonucleotides, are the monomers of RNA
  15. 21 • Common representation of the primary structure of DNA or RNA molecules is to write the nucleotide sequences from left to right synonymous with the 5' -----> 3' direction • Known as Sugar-phosphate backbone Condensation commonly occurs between 5'-phosphate of one nucleotide and 3'-hydroxyl of a second (Phosphodiester bond)
  16. 22 (i) Deoxyribose Nucleic Acid (DNA) • DNA contains two polynucleotide strands wound around each other and form helical structure • The backbone of each consists of alternating deoxyribose and phosphate groups bonded to the 5' carbon atom of one deoxyribose is covalently bonded to the 3' carbon of the next • The backbone of sugar phoshate of each strand is on the outside of the double helix, whereas the purine and pyrimidine bases are inside
  17. 23
  18. 24 • The two strands are "antiparallel"; that is, one strand runs 5′ to 3′ while the other runs 3′ to 5′. • Purine or Pyrimidine attached to each deoxyribose projects in toward the axis of the helix
  19. 25 • The most important aspect of the DNA double helix is the specificity of the pairing of bases.
  20. 26 DNA replication or duplication • DNA replication is the process by which a replica or identical copy of DNA are made in the cells • Cells do not live forever, they must pass their genetic information on to new cells • It is also required that fragments of DNA (genes) have to be copied to code for particular bodily function • It is essential that the replication of it is EXACT
  21. 27 • In order for replication to occur, the following must be available: キ The actual DNA to act as an exact template キ A pool of relevant and freely available nucleotides キ Supply of the relevant enzymes to stimulate reaction キ ATP to provide energy for these reactions
  22. 28 • During replication of DNA, the two strands of a double helix unwind and separate. • Each parent strand act as a template for the formation of a new complementary strand.
  23. 30 (ii) Ribonucleic acid (RNA) • RNA is a long unbranched macromolecule consisting of nucleotides joined by 3' - 5' phosphoester bonds. • RNA are responsible for putting the genetic information to use in protein synthesis. • Unlike DNA, RNA molecules have single strands; it does not have complementary base ratios and the sugar unit in RNA is a ribose rather than dioxyribose. • One of the four bases in RNA is Uracil (U) instead of thymine (T). • Uracil like thymine form a base pair with Adenine (A).
  24. 31 There three types of RNA  (a) Messenger RNA – (mRNA) (b) Ribosomal RNA (rRNA) and (c)Transfer RNA (tRNA)
  25. 32 (a) Messenger RNA (mRNA) • Account for 5 – 10% of the cell RNA. This is a single- stranded molecule formed on a single strand of DNA by the process known as transcription. • In the formation of mRNA only one strand of the DNA molecule is copied i.e. the base sequence is complementary to that of its DNA template. • mRNA act as the template for protein synthesis and it carries genetic information from DNA for the AAs sequences of the protein to be synthesized.
  26. 33 (b) Ribosomal RNA (rRNA) • These are found in cell ribosomes and accounts for 75 – 80% of cell RNA. • It is synthesized by genes present on the DNA. • The base sequence of rRNA is similar in all organisms from bacteria to higher plants and animals. • Ribosomes are the sites of protein synthesis. Here the mRNA code is translated into a sequence of amino acids in a polypeptide chain.
  27. 34 (c)Transfer RNA (tRNA) • These account for 10 – 15% of the cell RNA. • tRNA transfer amino acids present in cytoplasm to the ribosome. • Acts as an intermediate molecule between the triplet code of mRNA and the amino acid sequence of the polypeptide chain. • They are carriers of activated amino acids during protein synthesis.