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 http://cienciasdejoseleg.blogspot.kr/2014/06/procedimiento-del-experimento_439.html 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 Chargaff’s data on pg. 107 of your textbook. What patterns do you notice? http://totallyhistory.com/erwin-chargaff/

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 Franklin’s 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 Chargaff’s 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-1927-2012/

Watson & Crick Ted Talk http://www.ted.com/talks/james_watson_on_how_he_discovered_dna

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 http://www.synapses.co.uk/genetics/tsg19.html

DNA forms a double helix http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-18/CB18.html

Supercoiling of DNA Nucleosomes help to supercoil the DNA. http://www.mhhe.com/cgi-bin/netquiz_get.pl?qfooter=/usr/web/home/mhhe/biosci/genbio/maderbiology7/student/olc/art_quizzes/0062fq.htm&afooter=/usr/web/home/mhhe/biosci/genbio/maderbiology7/student/olc/art_quizzes/0062fa.htm&test=/usr/web/home/mhhe/biosci/genbio/maderbiology7/student/olc/art_quizzes/0062q.txt&answers=/usr/web/home/mhhe/biosci/genbio/maderbiology7/student/olc/art_quizzes/0062a.txt

Nucleosomes Textbook pg. 348: do the activity “Visualizing Nucleosomes” Use this link (on Haiku): http://www.rcsb.org/pdb/101/motm.do?momID=7&evtc=Suggest&evta=Moleculeof%20the%20Month&evtl=OtherOptions 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 http://mmbr.asm.org/content/75/2/301.figures-only

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 http://www.biologyexams4u.com/2013/04/steps-involved-in-dna-replication-in.html#.VMYqk2SUdsA

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