Survey of Biomolecules Part IV: Nucleotides and Nucleic Acids

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Survey of Biomolecules Part IVNucleotides and
Nucleic Acids

• Lecture Supplement
• Take one handout from the stage

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Final Exam

• Date Monday June 11
• Time 1130 AM - 230 PM
• Location Last name A-Ne in Ackerman Union Grand
  Ballroom
• Last name Ng-Z in Moore 100
• Topics Part A Noncovalent Molecular
  Forces through Nucleic Acids
• X-ray
  Crystallography not included
• Part B Comprehensive
• Stuff to bring
• Pen, pencil, eraser, models
• Picture ID required
• Self-addressed 8.5 x 11 envelope, 3 x 41 cent
  stamps, for exam return
• Focused Problem Solving Session - Hosted by Rich
• Saturday June 9, 100-250 PM, La Kretz 110
• email problem suggestions to richbrodriguez_at_yahoo.
  com

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Name Address
8.5
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Early History
1869 Friedrich Miescher isolates nuclein from
white blood cells Early 20th century Nuclein
found to consist of three fundamental components
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Nucleosides and Nucleotides

• 1920s Phosphoric acid 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)
• Nucleotide nucleoside with phosphate on 3' or 5'
  carbon

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DNA is a Polymer
1939 DNA is a polymer of many nucleosides linked
by 3', 5'-phosphodiesters

• Nucleoside sequence DNA or RNA primary
  structure (compare protein primary structure)

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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 the hot topic in
biology
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Chargaff's Rules
1950's Erwin Chargaff studies heterocyclic base
ratios in DNA from various organisms

• Chargaff's Rules In DNA of all organisms...
• (GA)/(CT) purines/pyrimidines ratio 11
• A/T ratio 11
• G/C ratio 11
• A/T and G/C ratios random in RNA

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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

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Watson-Crick Base Pairs

• Heterocyclic bases associate via two or three
  hydrogen bonds
• Base pairs similar size and shape ? efficient
  packing into double helix

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Based-Paired Double Helix
5' end 3' end
3' end 5' end
DNA strands are antiparallel
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Based-Paired Double Helix
Publication Watson and Crick, Molecular
Structure of Nucleic Acids A Structure for
Deoxyribose Nucleic Acid, Nature 1953, 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)
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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

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The End
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Chemistry 14C Student Evaluation of Instruction
Blue Form for Learning Manager Dr H
142-044-200 Orange Form for Instructional
Associates Farnosh Family 142-044-201 Robyn
Hodgkins 142-044-213 Steve Joiner
142-044-203 JC Olsen 142-044-207 Richard
Rodriguez 142-044-202 Good luck on all your
finals!