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Lecture 9 Some notes about entropy Molecular Biology continued

Lecture 9 Some notes about entropy Molecular Biology continued How does genetics help us to find interesting objects and find relationships between them?. There will be NO LECTURE on Tue, March 3. The Gibbs free energy:. The process A → B will go spontaneously if. The ENTROPY.

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Lecture 9 Some notes about entropy Molecular Biology continued

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  1. Lecture 9 Some notes about entropy Molecular Biology continued How does genetics help us to find interesting objects and find relationships between them? There will be NO LECTURE on Tue, March 3

  2. The Gibbs free energy: The process A→B will go spontaneously if

  3. The ENTROPY Statistical definition Classical definition (from analysis of steam machines) dQ– heat imparted to the system by the surroundings W = multiplicity of microscopic degrees of freedom (# of microstates) k – Boltzmann constant B P A V

  4. What if microstates are occupied unequally? How to write the entropy? n p – probabilities of states 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 lattice position S = min S = max Show this!

  5. Classical property of entropy: for a mole of ideal gas: integrating (a = integration constant) or

  6. At constant T and n so, entropy logarithmically depends on concentration

  7. If perfect Watson-Crick pairing was strictly enforced, then every organism should have no less than 61 different tRNAs. Many creatures get away with a considerably smaller variety because of the ‘promiscuity’ or ‘wobble’ at the third position in many codons. Phe codons UUU and UUC (5’-3’) can both be recognized by the tRNA that has GAA (5’-3’) anticodon

  8. T. thermofilus 70S ribosome (M. Yusupov et al., 2001)

  9. Low-resolution (EM) model of E. coli 70S ribosome

  10. The assembly of a functional ribosome starts with initiation factors elF6 and elF3

  11. Methionyl-tRNAiMet recognizes the AUG start codon before mRNA is loaded There are two types of Met tRNA: Initiation tRNA can bind only to the P site Met tRNA used in synthesis can bind to A site and than translocate E site P site A site

  12. Binding of incoming amino acyl tRNA Peptyidyl transferase reaction Translocation

  13. Termination is assisted by RFs (release factors) UAA – stop codon

  14. Circular structure of mRNA increases the translation efficiency

  15. The replication fork: leading strand and lagging strand

  16. LargeT = helicase Pol a = priming DNA polymerase Pol d = DNA polymerase PCNA - displaces Pol a

  17. Why GENETICS? (Chapter 5)

  18. Diploid organisms In Haploid organisms complementig genes can be expressed on extra-chromosomal elements (plasmids), i.e. “in trans” X X

  19. Generation of temperature-sensitive mutations

  20. Testing mutants for complementation and sorting them into complementation groups

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