4.2 Gene Separate clusters (mammals birds B2 clusters are I 口 formed by Expansion of cluster 02 duplication and divergence Separation of genes Linked o&B Figure 4.3 All globin genes (Xenopus) Duplication divergence genes have evolved by 8n品 a series of duplications. Ancestral globin (myoglobin transpositions,and Exon fusio Intron insertion mutations from a Leghemoglobin (plants) single ancestral gene 700600500400300200100 Million years 情華大兰
Figure 4.3 All globin genes have evolved by a series of duplications, transpositions, and mutations from a single ancestral gene. 4.2 Gene clusters are formed by duplication and divergence
4.3 Sequence divergence is the basis for the evolutionary clock Divergence is the percent difference in nucleotide sequence between two related DNA sequences or in amino acid sequences between two proteins. Evolutionary clock is defined by the rate at which mutations accumulate in a given gene. Replacement sites in a gene are those at which mutations alter the amino acid that is coded 清苇大当
Divergence is the percent difference in nucleotide sequence between two related DNA sequences or in amino acid sequences between two proteins. Evolutionary clock is defined by the rate at which mutations accumulate in a given gene. Replacement sites in a gene are those at which mutations alter the amino acid that is coded. 4.3 Sequence divergence is the basis for the evolutionary clock
4.3 Sequence Corrected percent divergence divergence is the basis for the 100 evolutionary clock 80 Figure 4.4 60 Silent sites Divergence of DNA sequences depends 40 on evolutionary separation.Each 20 Replac ement sites point on the graph represents a pairwise 100 200 300 400 500 comparison. Million years of separation 清菜大当
Figure 4.4 Divergence of DNA sequences depends on evolutionary separation. Each point on the graph represents a pairwise comparison. 4.3 Sequence divergence is the basis for the evolutionary clock
4.3 Sequence divergence is the basis for the evolutionary 02 clock Figure 4.5 Replacement site divergences between pairs of b-globin genes 500 allow the history of the human cluster to be 200 reconstructed.This tree 40 8 accounts for the separation of classes of B 600500400300200 100 globin genes Million years 清菜大兰
Figure 4.5 Replacement site divergences between pairs of b-globin genes allow the history of the human cluster to be reconstructed. This tree accounts for the separation of classes of globin genes. 4.3 Sequence divergence is the basis for the evolutionary clock
4.4 Pseudogenes are dead ends of evolution Processed pseudogene is an inactive gene copy that lacks introns,contrasted with the interrupted structure of the active gene.Such genes presumably originate by reverse transcription of mRNA and insertion of a duplex copy into the genome. 清菜大学
Processed pseudogene is an inactive gene copy that lacks introns, contrasted with the interrupted structure of the active gene. Such genes presumably originate by reverse transcription of mRNA and insertion of a duplex copy into the genome. 4.4 Pseudogenes are dead ends of evolution