Structure & Replication
DNA Structure & Replication Organic compounds Can you name all 4 macromolecules and their monomer?
Carbohydrate Monosaccharide Lipid Fatty acid/glycerol Protein Amino Acid Nucleic Acid Nucleotide Contributing Scientists
Hershey & Chase Chargaff Franklin Watson and Crick Hershey & Chase What is genetic material made of? DNA vs. Protein
What is genetic material made of? DNA vs. Protein https://paulingblog.wordpress.com/2009/08/18/the-hershey-chase-blender-experiments/ Chargaff Take a look at Chargaffs data on pg. 107 of your textbook.
What patterns do you notice? Franklin Maurice Wilkins and Rosalind Franklin Rosalind Franklin
Were using a technique called X-ray diffraction to study molecular structure Rosalind Franklin Produced a picture of the DNA molecule using this technique The cross in the center indicates that the molecule is helical in shape. The angle of the cross showed the pitch of the helix. The distance between bars showed the turns of the helix to be 3.4nm apart. The distance between the middle of the pattern and the top showed the repeating structure every 0.34nm. (a) Rosalind Franklin Franklins X-ray diffraction Photograph of DNA (b) Figure 16.6 a, b Watson & Crick Repeatedly built models based on incoming evidence about the structure of DNA. The first failed model did not take into account Franklins nor Chargaffs findings. Once DNA structure was elucidated, it led to all sorts of discoveries about how DNA is copied, used, and inherited. https://iconicphotos.wordpress.com/2012/02/13/antony-barrington-brown / Watson & Crick Ted Talk Nucleotide Components
Phosphate Group Sugar Nitrogenous Base H Sugar Bases Adenine Thymine Guanine Cytosine Sugar Phosphate Backbone DNA Double Stranded, Antiparallel
Hydrogen Bonds Covalent Bond DNA forms a double helix
Supercoiling of DNA Nucleosomes help to supercoil the DNA.
Nucleosomes Textbook pg. 348: do the activity Visualizing Nucleosomes Use this link (on Haiku):and click on the two Discussed structures at the bottom of the page to manipulate the 3D structures Supercoiling Animation: http://www.youtube.com/watch?v=OjPcT1uUZiE
DNA Replication The structure of DNA suggests a method for copying DNA. When does DNA replication occur? During the S-phase of interphase! DNA replication is semi-conservative. Meselson and Stahl obtained evidence for this. 1. 3. 2. 4. Meselson & Stahl Read about their experiment on pg. 112 113, then do the DBQ starting on pg. 113 114. Helicase Unwinds & unzips DNA Gyrase AKA topoisomerase
Releases the strain that develops ahead of the helicase. DNA Gyrase Single Strand Binding Proteins
Keep the strands apart long enough to be copied. SSBP http://www. biologyexams4u
DNA Primase Creates an RNA primer (5 to 3) After Primase DNA Polymerase III Adds free-floating DNA nucleotides (5 to 3 covalent bonds) Complementary base pairing After DNA polymerase III Okazaki fragments DNA Polymerase I Removes RNA primer & replaces it with DNA Ligase Seals the gaps between fragments As ligase acts After ligase The end REsult