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Molecular Evolution

Molecular Evolution

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Molecular Evolution

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  1. Molecular Evolution Lecture 1. Origins of variation: gene structure

  2. Why this course • A Human Language Gene Changes the Sound of Mouse Squeaks • Of Mice and Monologues • The Origins of Lactase Persistence

  3. II. What is DNA? A. DNA 1. Composition: polymer of nucleotides: 1. Nitrogen base 2. Deoxyribose [ribose for RNA] 3. Phosphate

  4. Types of nitrogen bases

  5. DNA nucleotides are attached to each other 5’ to 3’

  6. Bases can form hydrogen bonds with a complimentary antiparallel DNA strand

  7. Specificpairing between the nitrogen bases

  8. The complete DNA alphabet (fyi) Symbol Meaning Origin of designation G G Guanine A A Adenine T T Thymine C C Cytosine R G or A puRine Y T or C pYrimidine M A or C aMino K G or T Keto S G or C Strong interaction (3 H bonds) W A or T Weak interaction (2 H bonds) H A or C or T not-G, H follows G in the alphabet B G or T or C not-A, B follows A V G or C or A not-T (not-U), V follows U D G or A or T not-C, D follows C N G or A or T or C aNy

  9. Some features of DNA • Purines pair with pyrimidines (e.g. # purines = # pyrimides) • The # of A = # of T; #G = # of C • (% G + C content of 2 species’ DNA will vary) • GC-rich DNA is more stable than AT-rich (more hydrogen bonding) • Two strands of the duplex lie antiparallel

  10. DNA replication

  11. leading strand 5’ to 3’ continuous replication lagging strand discontinuous replication

  12. The genetic code: redundancy compensating for mutation http://upload.wikimedia.org/wikipedia/commons/a/ac/GeneticCode21.svg

  13. Redundancy and the Wobble position 5’ 5’ 3’ 3’

  14. Functional redundancy in the amino acid code • http://www.russell.embl-heidelberg.de/aas/general.html

  15. Eukaryotic Prokaryotic Polycistronic Monocistronic 5’ methylated G cap No cap Poly A tails No tails Transported from nucleus to cytoplasm Transcription/Translation coupled Half-life: minutes - hours Half-life: seconds - minutes Transcription/translation Differences between prokaryotic and eukaryotic mRNAs gene A 5’ gene B gene C 3’ 3’ 5’ Transcription 5’ Translation C A B

  16. Transcription/Translation