Unit 5 dna etc for moodle 2013

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Unit 5 dna etc for moodle 2013

  1. 1. DNA, RNA, and Gene Expression Biology 163 Unit 5 DNA and Genetic Engineering Chapters 12, 13, & 15
  2. 2. DNA Structure and Components   Double Helix – 2 strands form a twisted ladder Subunits of nucleotides contain:     Sugar – deoxyribose Phosphate Group (PO4-) Nitrogen Base Backbone (“uprights”) made of deoxyribose and phosphate
  3. 3. Nitrogen Bases  Purines – 2 rings    Pyrimidines – 1 ring    Adenine Guanine Thymine Cytosine Order of bases contains the “code” to make proteins
  4. 4. DNA Structure and Components - Phosphate Group (PO4-) Purines (2 rings) DNA Nucleotides Adenine Guanine - Nitrogen Base Thymine Pyrimidines (1 ring) Sugar: Deoxyribose - 5 carbons - Cytosine
  5. 5. DNA Base Pairing    Adenine pairs with Thymine Guanine pairs with Cytosine Bases (“rungs”) are connected by hydrogen bonds
  6. 6. Discovering DNA  Many scientists worked to understand the DNA structure Source of DNA T G C Streptococcus 29.8 31.6 20.5 18.0 Yeast 31.3 32.9 18.7 17.1 Herring 27.8 27.5 22.2 22.6 Human  A 30.9 29.4 19.9 19.8 Chargraff’s rule: [G] = [C] and [A] = [T] ;
  7. 7. Discovering DNA   1952 - Rosalind Franklin studied DNA using x-ray 1953 – James Watson and Francis Crick determined the double helix structure
  8. 8. DNA and Chromosomes Chromosome Nucleosome DNA double Coils Supercoils Histones – proteins which DNA is wrapped around helix
  9. 9. Replication Fork DNA Replication  DNA replicates during S phase of interphase    DNA Polymerase 2 copies needed for mitosis New Strand New Each strand serves as Strand a template for the new Origina l strand Strand Replication Fork Results in 2 identical DNA molecules Nitrogen Bases Original Strand DNA Polymerase
  10. 10. DNA Replication 1) Parent DNA has complementary strands 2) H bonds break, “unzipping” the DNA 3) Using the parent strand as a template, new DNA strands form -DNA polymerase 4) New backbones form – two new DNA molecules
  11. 11. DNA Replication  Semi-conservative replication – each new molecule contains one old strand and one new strand http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter14/ animations.html#
  12. 12. RNA Structure and Composition   RNA – ribonucleic acid Nucleotides made of:     Ribose Phosphate group Nitrogen Bases Same bases as DNA except uracil instead of thymine
  13. 13. DNA vs. RNA DNA RNA Type of Sugar Deoxyribose Ribose # of Strands 2 1 Nitrogen Bases A, C, T , G A, C, U , G Nucleus only Nucleus, cytoplasm, or ribosome Location in the Cell
  14. 14. Types of RNA mRNA “messenger” tRNA “transfer” rRNA “ribosomal” made using DNA transfers an amino acid to the growing protein makes up the bulk of ribosomes carries genetic info from the nucleus to the ribosome every 3 bases (codon) specifies an amino acid cloverleaf shape 3 complimentary bases (anticodon) binds to the mRNA codon
  15. 15. Protein Synthesis: two parts!  Transcription: DNA mRNA   occurs in the nucleus Translation: mRNA  protein  occurs on the ribosome (in the cytoplasm)
  16. 16. Transcription (RNA Synthesis)    One strand of DNA serves as a template for the synthesis of mRNA Occurs in the nucleus RNA polymerase joins RNA nucleotides
  17. 17. Translation (mRNA to Protein)      mRNA attaches to ribosome Each tRNA carries one amino acid Anticodon on tRNA matches with a codon on mRNA Amino acids join forming a polypeptide chain Long polypeptide chains form protein!!!
  18. 18. Protein Synthesis Summary
  19. 19. How does DNA “code” for protein?   Each codon codes for 1 of 20 amino acids What amino acid chain would form from the mRNA: AUGGUCCAA Met–Val–Glu
  20. 20. The Genetic Code   64 different combinations of RNA bases 1 “start” codon   Methionine 3 “stop” codons
  21. 21. Mutations… oops!    Mutations can be harmful or helpful May lead to cancer or genetic disorders May result in a new positive trait Deletion Duplication Inversion Translocation

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