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FINDING DNA The Race is on… APRIL 25 The day commemorates the completion of the Human Genome Project (complete mapping of genes of humans) in April 2003, and the discovery of DNA's double helix. Finding the A T C G order of an average human and what it codes for Chromosome #9 Was the genetic material protein or DNA? • Chapt. 9 Mendel (peas) did not know about DNA. • • Worksheet links Bozeman Biology: DNA and RNA Part I Bozeman Biology: DNA and RNA Part II The Race to Find DNA Youtubes • Finding the Structure of DNA (9:15) • The Secret of Photo 51 (55 minutes) • Watch Friday, April 24 • The story of Rosalind Franklin (2:24) - Get out CHART: DNA Race Scientists • Frederick Griffith • A medical officer was trying to find a vaccine against pneumococcus Rough and Smooth Pneumococcus benign No capsule virulent Thick capsule Griffith 1920’s • Streptococcus pneumoniae used to show a “transforming factor” • bacteria transformation youtube (23 seconds) Griffith’s Conclusion • Some material* in the heat-killed S strain of pneumococcus that was responsible for “transforming” the R-strain into a lethal form • transformation = passing the inheritance factor* from one organism to another • *THIS TRANSFORMING FACTOR WAS LATER FOUND TO BE DNA Nerd Cartoons Oswald Avery 1944 He had reported that DNA, not protein (which was believed at the time), was the hereditary substance (transforming material). Studied medical research Oswald Avery 1940’s Avery’s Conclusion • EXPERIMENT: Separated the DNA, RNA, protein from S-strain pneumococcus • AVERY PROVED THAT DNA WAS THE TRANSFORMING MATERIAL Alfred Hershey and Margaret Chase 1953 • Showed that the hereditary material in bacteriophage viruses is DNA. DNA in water • Hershey-Chase Bacteriophages Youtube (1:49) • McGraw-Hill Hershey-Chase Experiment Radioactive P32 in DNA Radioactive S35 in protein Hershey-Chase • CONCLUSION – • DNA is genetic material 32 because ( P) nucleic acid not (35S) protein guides viral replication Bacteriophages (“bacteria-eaters”)get handout Virus Examples • Cold Virus HIV Virus Bird Flu Virus Ebola Virus Herpes Virus Bacteriophage Structure (Capsid) D A B E C Virus: Are they Alive? • Viruses can only replicate in a living host. • "Viruses straddle the definition of life. Viruses contain some of the structures and exhibit some of the activities that are common to organic life, but they are missing many of the others.” • Dr. Mark Young of MSU youtube (4:00) • Are virusees alive? (2:57) Bacteriophage Virus Lytic Infection 1.Attach to host (E. coli) 2. Insert DNA 3. Make DNA parts 4.assemble DNA parts 5. Lyse (burst)-kills EXAMPLES: Cold Flu Lysogenic Infection • 1. Virus lands on host. • 2. Virus injects DNA into host. • 3. Virus DNA attaches to host DNA = prophage. • 4. Virus Prophage will become lytic when conditions are favorable (you are sick, tired). • lysogenic infection youtube (1:25) • Mr. W's "I'm a virus“ (4:02) PROPHAGE: viral gene inserted and integrated into the circular bacterial DNA chromosome …forever Lysogenic: Will replicate with the host cell…forever. Lysogenic Cycle Animation • Animation Quiz 2 - Lamda Phage Replication Cycle • EXAMPLES: HERPES HIV • CHICKEN POX Identifying Bacteria: Shapes • Cocci- spherical • Bacilli – rod • Spirilla – spiral Identifying bacteria: Groupings • Diplo: Two Staphylo : cluster Sarcina: 8 Tetrad: 4 Strepto:chain Bacterial Shapes and Arrangements • Gram + and Gram – Tests +/endospore Sugar Test Aerobic/anaerobic test Keep a checklist of results Who am I? Who am I? streptobacillus What is the structure of DNA? • It is a nucleic acid (macromolecule) • Polynucleotide (polymer) = Made of long chains of Nucleotides (monomers) DNA Nucleotide “monomer of nucleic acid” Phosphate Group O O=P-O O 5 CH2 O N C1 C4 Sugar (deoxyribose) C3 C2 Nitrogenous base (A, G, C, or T) DNA Structure Macromolecule: Nucleic Acid • POLYMER: • MONOMER: NUCLEOTIDE POLYNUCLEOTIDE Ladder sides “rungs” A Nucleotide • MADE OF: –Sugar –Phosphate –Base • Deoxyribose sugar • PO4 • 4 kinds of bases: • (A) (G) (T) (C) (names on next slide) 4 Types of Base Pairs • A = adenine • T = thymine • C = cytosine • G = guanine • NOW SING THE DNA SONG (next slide) DNA Song (to the tune of “row, Row, Row Your Boat”) • • • • • We love DNA Made of Nucleotides Sugar, phosphate, and a base • Row Bonded down one side Your Adenine with thymine make a Boat lovely pair Karaoke • Cytosine without guanine would feel very bare Nitrogenous Bases • PURINES -2 rings 1. Adenine (A) AG = silver 2. Guanine (G) • PYRIMIDINES -1 ring 3. Thymine (T) 4. Cytosine (C) CUT A or G T or C DNA •Deoxyribonucleic Acid Purine = AG Pyrimidine = CUT • Covalent bonds between a phosphate and two sugar molecules (phosphodiester). • H-bonds between complimentary bases DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C) “Legs of ladder” Phosphate & Sugar Backbone DNA backbone • Sugar • Phosphate DNA Structure • Rungs of the Ladder: – Various orders of A, T, C, G • Backbone: – Sugar and phosphates – Alternate DNA Double Helix 5 O 3 3 O P 5 O C C G G 1 P 5 3 2 4 4 2 3 1 P T 5 A P 3 O O P 5 O 3 5 P What’s RNA? • Ribonucleic Acid –Three types: –mRNA –tRNA –rRNA Comparing DNA and RNA “two kinds of nucleic acids” • DNA • RNA • Double stranded • Sugar = deoxyribose • Bases: A-T, C-G • Found only in nucleus • Can repair itself • • • • • Single stranded Sugar = ribose Bases: A-U, C-G U=uracil Found in and out of the nucleus • Cannot repair itself RNA DNA Pretty Similar • Uracil • Thymine DNA - Contains Thymine - Contains deoxyribose sugar - Double stranded molecule - Found only in nucleus Both RNA - Made of nucleotides - Single stranded molecule - Contain adenine, guanine and cytosine - Contains uracil - Contains ribose sugar - Found in nucleus and cytoplasm • Bozeman Biology DNA and RNA Part 1 • Griffith, Avery, Hershey and Chase, Watson and Crick, pro and eukaryotic chromos • Bozeman Biology DNA and RNA part 2 • DNA replication • Transformation • Protein synthesis • • • • • • • Relative Proportions (%) of Bases in DNA Organisms A T G C Human 30.9 29.4 19.9 Chicken 28.8 29.2 20.5 Grasshopper 29.3 29.3 20.5 Sea Urchin 32.8 32.1 17.7 Wheat 27.3 27.1 22.7 Yeast 31.3 32.9 18.7 E. coli 24.7 23.6 26.0 19.8 21.5 20.7 17.3 22.8 17.1 25.7 Question: • If there is 30% Adenine, how much Cytosine is present? • HINT: A –T and C - G Answer: • There would be 20% Cytosine. Adenine (30%) = Thymine (30%) Guanine (20%) = Cytosine (20%) Total of 100% Chargaff’s Rules • the amount of (A)denine will always equal the amount of (T)hymine • And HOT!!! • the amount of (G)uanine will always equal the amount of (C)ytosine. Nitrogenous Bases • Why does A bond only with T and C only with G? • What do you notice? Nitrogenous Bases T and C are single-ring Pyrimidines A and G are double-ring Purines A single bonds with a double 2 chains of nucleotides bind to form a DNA molecule • Hydrogen bonds form between the nitrogenous bases to join the 2 chains together • The sugar and phosphate group together is known as the sugar-phosphate backbone ENZYMES FOR DNA REPLICATION • Helicase = separates 2 DNA strands (breaks H bonds) • Primase=RNA primers at INITIATION REPLICATION ENZYMES • Topoisomerase = unwinding DNA • DNA Polymerase = Adding of DNA nucleotides ELONGATION (proofread and repair) DNA REPLICATION ENZYMES • LIGASE= Binds the Okazaki fragments • Watch the enzymes in DNA Replication Animation AT and C-G Base Pairing • DNA Replication simple version) (link) • Media Showcase (cool animation link) • Detailed Replication Link DNA STRUCTURE • A-T • C-G • in tons of combinations makes our genetic code DNA Replication •Hi!...Still Awake? •DNA Replication Animation click here What is the complementary base sequence on the other strand of the DNA? A T T G C C C T A A • T A A C G G G A T T The Race is On! • To Determine the Structure of the DNA molecule. Rosalind Franklin • Rosalind Franklin was an English chemist who was working in an X-ray crystallography lab in Paris, France in 1951. FAMOUS PHOTO 51 (correct orientation of DNA)double helix • Taken with her PhD student Raymond Gosling Tells you there are 10 bases/turn Linus Pauling • American biochemist suggested helix (spiral)shape • Most famous for Vitamin C prevents colds DNA Geek • Linus Pauling was a Caltech chemist (USA), who in 1951 had discovered the alpha helical nature of protein structure. I remember his books: Vitamin C and the Common Cold and Cancer and Vitamin C also The Nature of the Chemical Bond and protested nuclear testing DNA Geeks • James Watson, a biologist from Indiana University, and Francis Crick, a physicist, were working at the Cavendish Lab in Cambridge, England Nobel Prize for structure of DNA Francis Crick (1916-2004) Narrative - 8. Watson and Crick - Linus Pauling and the Race for DNA: A Documentary History • Born in England • Worked at Cambridge Crick’s first DNA sketch Worked on DNA structure with Watson James Watson (1928- ) • American age 22 • Ph.D. degree in Zoology in 1950 • Worked with Crick at the King’s College on the structure of DNA • At age 12 starred on QUIZ KIDS TV show • Recently at Cold Spring Harbor, NY, head of HGP Watson and Crick Met and worked at the Cavendish Laboratory Watson and Crick’s Wire Model DOUBLE HELIX Watson and Crick are "Lucky“ youtube(2:21) DNA Geek Maurice Wilkins (1916-2004) • New Zealand Born British Scientist • It was his idea to study DNA by X-ray crystallographic techniques • Nobel Prize DNA Base Pairs • Adenine with Thymine • Guanine with Cytosine X ray Diffraction Franklin’s Suggestion DNA Bases Franklin corrects Watson and Crick • Told them their first model was incorrect • They had put the bases on the outside The Scandal • Watson used her pictures (Photo 51) to determine that DNA spirals into a double helix. • Little did Rosalind Franklin know that her laboratory colleague, Maurice Wilkins, was in the next room revealing months of her work to her competitor! Rosalind Franklin • Died of ovarian cancer at age 37 and so could not share in the Nobel Prize • Her work did lead the way to work on viruses Watson and Crick “stole” her Photo 51 information • She was not included in the publication that reported the structure of DNA and she died before the Nobel Prize was given to Watson and Crick. Nobel Prize • In 1962 James Watson, Francis Crick, and Maurice Wilkins jointly received the Nobel Prize in medicine or physiology for their determination in 1953 of the structure of deoxyribonucleic acid (DNA). • Mr. W's DNA Rap Violation of the Scientists' Code of Honor • It is necessary for scientists to share information with one another, for if they did not, science and knowledge would not develop and grow. However, the tacit agreement among scientists who use or borrow one another's findings is that proper credit must be given to the author or originator of the work. Beadle and Tatum’s Experiment • used X rays to cause mutations in strains of the mold Neurospora (a bread mold) • were able to create single gene mutations that incapacitated specific enzymes Beadle and Tatum The One Gene/One Enzyme Hypothesis Used bread mold Beadle and Tatum 1941 George W. Beadle (1903-1989) and Edward L. Tatum (1909-1975) show how genes direct the synthesis of enzymes that control metabolic processes REVISED BEADLE AND TATUM: • One gene- one polypeptide EXPLAIN: •“The secret of life is complementarity.”