Evolutionary chronometer Evolutionary distance between two organisms can be measured by differences in the nucleotide or amino acid sequence of homologous macromolecules isolated from them两物种的进化距离可通过比较来自它们的同 源大分子的核苷酸序列或氨基酸序列而测定 Chen Feng,Shanghai Jiao Tong University
Chen Feng, Shanghai Jiao Tong University Evolutionary chronometer Evolutionary distance between two organisms can be measured by differences in the nucleotide or amino acid sequence of homologous macromolecules isolated from them 两物种的进化距离可通过比较来自它们的同 源大分子的核苷酸序列或氨基酸序列而测定
Ribosomal RNA as Molecular Chronometer 16S/18S rRNA gene(functionally constant, universally distributed,and moderately well conserved in sequence across broad phylogenetic distances) ATPase (membrane-bound enzyme complex that can synthesize and hydrolyze ATP) RecA(protein required for genetic recombination) Chen Feng,Shanghai Jiao Tong University
Chen Feng, Shanghai Jiao Tong University Ribosomal RNA as Molecular Chronometer 16S/18S rRNA gene(functionally constant, universally distributed, and moderately well conserved in sequence across broad phylogenetic distances) ATPase (membrane-bound enzyme complex that can synthesize and hydrolyze ATP) RecA (protein required for genetic recombination)
rRNA molecules The counterpart to 16S rRNA in eukaryotes is 18S rRNA Nucleotides:16S (~1500) Nucleotides: -21+ proteins 55 235 (~120)(~2900) 30S subunit ~34← proteins 50S subunit 705 ribosome (c) (a) (b) Figure 11-11 Brock Biology of Microorganisms 11/e 2006 Pearson Prentice Hall,Inc Primary and secondary structure of 16S rRNA of Electron micrograph of E.coli 70S ribosomes from E.coli
rRNA molecules Electron micrograph of 70S ribosomes from E.coli Primary and secondary structure of 16S rRNA of E. coli The counterpart to 16S rRNA in eukaryotes is 18S rRNA
16S rRNA from Archea has general similarities in secondary structure(folding)but numerous differences in primary structure (sequence). 大肠埃希氏菌 万氏甲烷球菌 酿酒酵母 Escherichia coli) Methanococcus vannielii) Saccharomyces cerevisiae 图12-1三界生物的16 SrRNA的比较 (图中粗黑线表示真细菌和古生菌的差异)
16S rRNA from Archea has general similarities in secondary structure (folding) but numerous differences in primary structure (sequence)
16.7 Evolutionary Analysis: Analytical Methods Isolate DNA 16S gene Amplify 16S gene by PCR Most scientists today employ Run on agarose gel:check for correct size PCR to amplify directly the Kilo- bases 1 2 3.0- genes encoding 16S rRNA from 2.0- 1.5- genomic DNA and then 1.0- sequence the PCR product by 0.5- Sequence standard dideoxy DNA sequencing Align sequences; generate tree Distinct Ancestral species cell Sequencing Methodology Distinct species of rRNArRNA的测序方法 2012 Pearson Education,Inc
Most scientists today employ PCR to amplify directly the genes encoding 16S rRNA from genomic DNA and then sequence the PCR product by standard dideoxy DNA sequencing. Sequencing Methodology of rRNA rRNA的测序方法 16.7 Evolutionary Analysis: Analytical Methods