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Bioinformatics Gene 阮雪芬 2002, Oct 3 NTUST www.ntut.edu.tw/~yukijuan/lectures/bioinfo/Oct3.ppt Key Organic Molecules Are Used By Living Systems Many Components of Biochemical Macromoleculaes Can Be Produced in Simple Prebiotic Reactions ~1 billions years after Earth’s formation, life appeared. The Urey-Miller experiment. 1950, Stanley Miller and Harold Urey Products of Prebiotic Synthesis Amino Acids Produced in the Urey-Miller experiment. Prebiotic Synthesis of a Nucleic Acid Component Adenine can be generated by the condensation of HCN. Genetic Material A nucleotide contains : A five-carbon sugar molecules One or more phosphate groups A nitrogenous base Ribose and Deoxyribose Backbone of DNA and RNA Purines and Pyrimidines Watson-Crick base pairs Watson-Crick base pairs X-ray Diffraction Photography of a Hydrated DNA Fiber Watson-Crick Model of Double Helical DNA The Double Helix DNARNAProtein Complementarity Between mRNA and DNA Promoter Sites for TranscriptionProkaryotic Genes Promoter Sites for TranscriptionEukaryotic Genes RNA Template-directed Polypeptide Synthesis Links the RNA and Protein Worlds (I) I RNA Template-directed Polypeptide Synthesis Links the RNA and Protein Worlds (II) II III Attachment of a Amino Acid to a tRNA Molecule Symbolic Diagram of an AminoacyltRNA The Features of the Genetic Code Three nucleotides encode an amino acid The code is nonoverlapping The code has no punctuation The genetic code is degenerate The code is nonoverlapping The code has no punctuation The genetic code is degenerate Initiation of Protein SynthesisProkaryotes Initiation of Protein SynthesisEukaryotes Transcription and Processing of beta-globin Gene Consensus Sequence for the Splicing of mRNA Precursors Bioinformatics Evolution Structural Similarity Often Follow Functional Similarity Angiogenin is Highly Similar to Ribonuclease Two Classes of Homologs Amino Acid Sequences Alignment with Gap Insertion The Generation of a Shuffled* Sequence * Randomly rearranged Statistical Comparison of Alignment Scores A Graphic View of the Blosum-62 Substitution Matrix Alignment with Conservative Substitutions Noted The odds: 1/20 The odds: 1/300 Alignment of Myoglobin and Leghemoglobin 23% identical Database Can Be Searched to Identify Homologous Sequences database Tertiary Structure Is More Conserved Than Primary Structure The Structures of Actin and Hsp-70 Cytoskeleton Heat Shock Protein 70: assists protein folding Convergent Evolution of Protease Active Site Structures of Chymotrypsin and Subtilisin Evolutionary Trees Can Be Constructed On the Basis of Sequence Information