DNA  Structure & Function
Key terms <ul><li>Genome  = complete set of  sequences  in the genetic material of an org.  </li></ul><ul><li>Nucleic acid...
<ul><li>Genotypic =  Replication . Store &transmit info. </li></ul><ul><li>Phenotypic =  Gene expression.  Control devlp o...
<ul><li>Chromosomes composed of 2 macmol. </li></ul><ul><li>i. Protein. </li></ul><ul><li>ii. Nucleic acids  DNA(d)  and R...
Structure of nucleotides.. <ul><li>A )  5 carbon pentose sugar ;  </li></ul><ul><li>  RNA = Ribose, DNA = Deoxyribose.   <...
Pentose sugars
Structure of nucleotides
 
 
Watson and Crick’s model <ul><li>double helix </li></ul><ul><li>sugar-phosphate backbone = sugar is deoxyribose  </li></ul...
 
Phosphodiester bonds.. <ul><li>A dinucleotide is formed when a condensation reaction occurs between the phosphate group of...
More nucleotides can  be added, building up  a long  polynucleotide chain.
<ul><li>The stability of the double helix is due to the large number of covalent,  H+  and hydrophobic bonds. </li></ul>
 
 
Double Helix.. Uprights = Sugar phosphate bond, Rungs = Bases (A+T/G+C) 2 strands running in opposite direction (5’ – 3’) ...
 
 
Genetic code <ul><li>These bases always pair up in the same way. </li></ul><ul><li>A single strand of DNA is made of lette...
Genetic code <ul><li>The instructions in a gene that tell the cell how to make a specific protein. A, T, G, and C. </li></...
Genetic code contd.. <ul><li>Inside the nucleus, the DNA message is copied onto RNA. to transmit the message or genetic co...
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Dna

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Dna

  1. 1. DNA Structure & Function
  2. 2. Key terms <ul><li>Genome = complete set of sequences in the genetic material of an org. </li></ul><ul><li>Nucleic acids = Macromolecules (large RMM). </li></ul><ul><li>Chromosomes = Discrete unit of the genome carrying many genes . NA and protein. </li></ul><ul><li>Gene = Segment of DNA specifying production of a polypeptide chain . It codes for a RNA protein. </li></ul>
  3. 3. <ul><li>Genotypic = Replication . Store &transmit info. </li></ul><ul><li>Phenotypic = Gene expression. Control devlp of phenotype. </li></ul><ul><li>Evolutionary = Mutation. Changes produce variations. </li></ul><ul><li>Fx…..preserving, copying and transmitting information. </li></ul>
  4. 4. <ul><li>Chromosomes composed of 2 macmol. </li></ul><ul><li>i. Protein. </li></ul><ul><li>ii. Nucleic acids DNA(d) and RNA(s) </li></ul>
  5. 5. Structure of nucleotides.. <ul><li>A ) 5 carbon pentose sugar ; </li></ul><ul><li> RNA = Ribose, DNA = Deoxyribose. </li></ul><ul><li>b) A nitrogen containing base; </li></ul><ul><li>2 Purines (A,G) 2 Pyrimidines (C,T/U) </li></ul><ul><li> RNA = CGA U , DNA = CGA T </li></ul><ul><li>c) A phosphate group </li></ul>
  6. 6. Pentose sugars
  7. 7. Structure of nucleotides
  8. 10. Watson and Crick’s model <ul><li>double helix </li></ul><ul><li>sugar-phosphate backbone = sugar is deoxyribose </li></ul><ul><li>4 types of nucleotide base : A, C, G, T </li></ul><ul><li>: 2 complementary strands where A = T, C = G in anti parallel fashion </li></ul><ul><ul><li>&quot;complementary“ = fitting together of 2 molecules with hydrogen bonds </li></ul></ul>
  9. 12. Phosphodiester bonds.. <ul><li>A dinucleotide is formed when a condensation reaction occurs between the phosphate group of one nucleotide and pentose of another forming a phosphodiester bridge linking the 2 nucleotides together. </li></ul>
  10. 13. More nucleotides can be added, building up a long polynucleotide chain.
  11. 14. <ul><li>The stability of the double helix is due to the large number of covalent, H+ and hydrophobic bonds. </li></ul>
  12. 17. Double Helix.. Uprights = Sugar phosphate bond, Rungs = Bases (A+T/G+C) 2 strands running in opposite direction (5’ – 3’) <>
  13. 20. Genetic code <ul><li>These bases always pair up in the same way. </li></ul><ul><li>A single strand of DNA is made of letters: ATGCTCGAATAAATG </li></ul><ul><li>The letters make words: ATG CTC GAA TAA ATG TGA ATT TGA </li></ul><ul><li>The words make sentences: <ATG CTC GAA TAA> <ATG TGA ATT TGA> </li></ul><ul><li>These &quot;sentences&quot; are called genes </li></ul>
  14. 21. Genetic code <ul><li>The instructions in a gene that tell the cell how to make a specific protein. A, T, G, and C. </li></ul><ul><li>3 letter word = codon = Triplet code. </li></ul><ul><li>Fx of codon = tell the cell how to make proteins </li></ul><ul><li>Start and stop codon. </li></ul>
  15. 22. Genetic code contd.. <ul><li>Inside the nucleus, the DNA message is copied onto RNA. to transmit the message or genetic code. </li></ul><ul><li>It has 4 subunits A, T, G, C and are arranged in triplet codes. Eg ATTGCCTAG read from left to right ATT/GCC/TAG. Each triplet code specifies different amino acids. </li></ul><ul><li>Eg. ATT = amino acid “X” </li></ul><ul><li>GCC = amino acid “Y” </li></ul><ul><li>TAG = amino acid “Z” </li></ul><ul><li>This piece of genetic code will instruct the cell to make a protein in which X,Y and Z are joined together in that order. </li></ul>

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