rav65819_ch24_471_488

rav65819_ch24_471_488 - 24 Genome Evolution introduction...

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;;;;;;;; 24 Genome Evolution introduction GENOMES CONTAIN THE RAW MATERIAL for evolution, and many clues to evolution are hidden in the ever-changing nature of genomes. As more genomes have been sequenced, the new and exciting field of comparative genomics has emerged and has yielded some surprising results and many, many questions. Comparing whole genomes, not just individual genes, enhances our ability to understand the workings of evolution, to improve crops and to identify the genetic basis of disease so that we may develop more effective treatments with minimal side effects. The focus of this chapter is on how comparative genomics is enhancing our understanding of genome evolution and how this new knowledge can be applied to improve our lives.
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chapter 24.4 Gene Function and Expression Patterns concept outline 24.5 Nonprotein-Coding DNA and Regulatory Function 24.6 Genome Size and Gene Number Noncoding DNA inflates genome size Plants have widely varying genome size 24.7 Genome Analysis and Disease Prevention and Treatment Distantly related genomes offer clues for causes of disease Closely related organisms enhance medical research Pathogen–host genome differences reveal drug targets 24.8 Crop Improvement Through Genome Analysis Model plant genomes provide links to genetics of crop plants BeneFcial bacterial genes can be located and utilized Gene inactivation results in psuedogenes Horizontal gene transfer complicates matters Chimp and human gene transcription patterns differ Speech is uniquely human: An example of complex expression 24.1 Comparative Genomics Evolutionary differences accumulate over long periods Genomes evolve at different rates Plant, fungal, and animal genomes have unique and shared genes 24.2 Evolution of Whole Genomes Ancient and newly created polyploids guide studies of genome evolution Plant polyploidy is ubiquitous, with multiple common origins Polyploidy induces elimination of duplicated genes Polyploidy can alter gene expression
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Transposons jump around following polyploidization 24.3 Evolution Within Genomes Individual chromosomes may be duplicated DNA segments may be duplicated Genomes may become rearranged 471 rav65819_ch24_471_488.indd 471 rav65819_ch24_471_488.indd 471 12/8/06 12:52:56 PM 12/8/06 12:52:56 PM 24.1 Comparative Genomics genetic differences between species in a very direct way, examining the footprints on the evolutionary path between different species. A key challenge of modern evolutionary biology is to find a way to link changes in DNA sequences, which we are now able to study in great detail, with the evolution of the complex morphological characters used to construct a traditional phylogeny. Many different genes contribute to complex characters—such as feathers, described in the preceding chapter. Making the connection between a specific change in a gene and a modification in a morphological character is particularly difficult. Comparing genomes (entire DNA sequences) of different species provides a powerful new tool for
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rav65819_ch24_471_488 - 24 Genome Evolution introduction...

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