4.2 Gene Separate clusters (mammals birds) 1 clusters are formed by y Expansion of cluster duplication and div Vergence Separation of genes Linked o&阝 Figure 4.3 All globin genes (Xenopus) Duplication divergance renes have evolved by Single globin gene hagfish a series of duplications Ancestral globin (myoglobin transpositions, and Exon fusil■ar■| tron insertion mutations from a ■■ Leghemoglobin (plants) single ancestral gene 700600500400300200100 消当
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 消当
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 evolutionary clock Figure 4.4 Silent sites Divergence of dna sequences depends 4 on evolutionary separation. Each 2 Replac ement site point on the graph represents a pairwise 100200300400500 comparison Million years of separation 消当
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 2 clock Figure 4.5 Replacement site divergences between pairs of b-globin genes 500 100 allow the history of the human cluster to be 200 reconstructed. This tree 40 accounts for the separation of classes of 6005004003002001000 globin genes Mⅲ on years 消当
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 消当
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