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The complete OWLS solutions set: OWLSsolutionstoallproblems.pdf

The complete OWLS solutions set: OWLSsolutionstoallproblems.pdf Final review session TODAY led by En- wei in CS24 from 3-4:20pm Final Exam:

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The complete OWLS solutions set: OWLSsolutionstoallproblems.pdf

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  1. The complete OWLS solutions set:OWLSsolutionstoallproblems.pdf Final review session TODAY led by En-weiin CS24 from 3-4:20pm Final Exam: - Each part is worth 100 points and you will have a total of 3 hours to complete both parts (you can work on them in any order you choose, or go back and forth between them).   - Part A will cover all the "new" material since Midterm 2. - Part B will be comprehensive and will cover the entire course.  Practice on old exams!http://www.chem.ucla.edu/harding/14C/14C_s12/14C_s12_syl.html#exams - Your final exam will be on Wednesday, June 13 from 8-11am. Last name A-C:  Please go to Young 2200 Last name D-Z:  Please go to CS50 - You may use your model kits! You will be provided with all the information you were given on Midterm 1 and Midterm 2

  2. Biomolecules Survey Part 4: Nucleic AcidsLecture Supplement page 248

  3. Heterocyclic base Heterocycle: Has a least one ring which includes an atom other than carbon Pyrimidines Cytosine (C) Thymine (T) DNA Uracil (U) RNA Phosphoric acid Purines Adenine (A) Guanine (G) X = OH, D-ribose X = H, 2-deoxy-D-ribose Early History 1869: Friedrich Miescher isolates “nuclein” from white blood cells Early 20th century: Nuclein found to consist of three fundamental components

  4. 5' or 1' 4' 3' 2' Adenosine (a nucleoside) Adenylic acid (a nucleotide) Nucleosides and Nucleotides • 1920’s: Carbohydrate + heterocyclic base = nucleoside • Heterocyclic base nitrogen bonded to ribofuranose anomeric carbon • Carbohydrate = ribose (X = OH) in ribonucleic acid (RNA) • = deoxyribose (X = H) in deoxyribonucleic acid (DNA) • Nucleoside + phosphoric acid = nucleotide (nucleoside with phosphate on 3' or 5' carbon)

  5. 1957 Nobel Prize in Chemistry to Lord Alexander Todd "for his work on nucleotides and nucleotide co-enzymes" (nobelprize.org) DNA is a Polymer 1939: DNA is a polymer of many nucleosides linked by 3', 5'-phosphodiesters • Nucleotide sequence = DNA or RNA primary structure(compare protein primary structure)

  6. DNA Carries the Genetic Code Before 1944: Proteins believed to carry genetic information DNA is not much more than a biological curiosity 1944: DNA demonstrated to be the cellular molecule that carries genetic information: Avery, Macleod and McCarty: Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III, Journal of Experimental Medicine, 1944, 79, 137-158. After 1944: DNA is thehot topic in biology

  7. Chargaff's Rules 1950's: Erwin Chargaff studies heterocyclic base ratios in DNA from various organisms Chargaff's Rules: In DNA of all organisms... • (G+A)/(C+T) = (purines)/(pyrimidines) ratio ~1:1 • A/T ratio ~1:1 • G/C ratio ~1:1 • Base ratios random in RNA

  8. } Not compatible with single helix } DNA is a base-paired double helix Watson and Crick made extensive use of models to study molecular structure. Follow their example! The Problem Solved 1953: • Rosalind Franklin: X-ray studies of DNA show helical structure Diameter = 20 Å Length = 34 Å per 360o turn Calculated density • James Watson and Francis Crick combine... • Franklin's x-ray data • Chargaff's rules • Examination of molecular models = secondary structure of DNA Franklin's Photo 51. The X pattern is characteristic of a helical structure

  9. Adenine-Thymine Guanine-Cytosine Watson-Crick Base Pairs same size • Heterocyclic bases associate via two or three hydrogen bonds • Base pairs similar size and shape  efficient packing into double helix

  10. Pi stacking Space-filling model: Atoms represented at their van der Waals radii (electron cloud volumes) Based-Paired Double Helix 5' end 3' end Hydrogen bonds easily disassembled Strong 3' end 5' end DNA strands are antiparallel

  11. Based-Paired Double Helix Publication: Watson and Crick, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, Nature1953, 171, 737-738 "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material." "We have also been stimulated by a knowledge of the general nature of the unpublished experiment results and ideas of ... Dr. R. E. Franklin..." 1962 Nobel Prize in Physiology or Medicine: to Wilkins, Watson, and Crick "for their discoveries concerning the molecular structure of nuclear acids and its significance for information transfer in living material" Optional reading: The Double Helix: A Personal Account of the Discovery of the Structure of DNA (Watson)

  12. The DNA Space Problem • Human genome = 3 x 109 base pairs (bp) • (3 x 109 bp) x (34 Å per 10 bp) x (10-10 m per Å) = ~1 meter in length • Solution: DNA tertiary structure = supercoiling

  13. Memorize DNA Structure?

  14. CTAGAAGTACGTCTT Glu Leu Leu Arg Val CTGGAAGTACGTCTA

  15. Origin of Life Variations of Life Origin of Universe Something Alive Nothing Something Alive (and complex!) Something http://jumk.de/astronomie/img/hdf.jpg http://rst.gsfc.nasa.gov/Sect16/full-20earth2.jpg http://complex.upf.es/~josep/RNA.jpg

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