Chapter 4 Clusters and repeats 莘大
Chapter 4 Clusters and repeats
Gene clusters are formed by duplication and divergence Sequence divergence is the basis for the evolutionary clock Pseudogenes are dead ends of evolution Unequal crossing-over rearranges gene clusters Genes for rRNA form tandem repeats (The repeated genes for rRNA maintain constant sequence) Crossover fixation could maintain identical repeats Satellite DNAs often lie in heterochromatin Arthropod satellites have very short identical repeats Mammalian satellites consist of hierarchical repeats Minisatellites are useful for genetic mapping 消当
Gene clusters are formed by duplication and divergence Sequence divergence is the basis for the evolutionary clock Pseudogenes are dead ends of evolution Unequal crossing-over rearranges gene clusters Genes for rRNA form tandem repeats ( The repeated genes for rRNA maintain constant sequence) Crossover fixation could maintain identical repeats Satellite DNAs often lie in heterochromatin Arthropod satellites have very short identical repeats Mammalian satellites consist of hierarchical repeats Minisatellites are useful for genetic mapping
4.1 Introduction Gene cluster is a group of adjacent genes that are identical or related Gene family consists of a set of genes whose exons are related; the members were derived by duplication and variation from some ancestral gene Satellite DNA consists of many tandem repeats (identical or related) of a short basic repeating unit Unequal crossing-over describes a recombination event in which the two recombining sites lie at nonidentical locations in the two parental DNA molecules 消当
Gene cluster is a group of adjacent genes that are identical or related. Gene family consists of a set of genes whose exons are related; the members were derived by duplication and variation from some ancestral gene. Satellite DNA consists of many tandem repeats (identical or related) of a short basic repeating unit. Unequal crossing-over describes a recombination event in which the two recombining sites lie at nonidentical locations in the two parental DNA molecules. 4.1 Introduction
4.1 Bivalent contains 4 chromatids. 2 from each parent Introduction AAa chiasma is caused by Figure 1.23 crossing-over between 2 of the chromatids AAa Bb Chiasma formation is Two chromosomes remain responsible parental( AB and a总 Recombinant chromosomes A or generating contain material from each parent, and have new genetic a combinations (Ab and aB) B recombinants a 消当
Figure 1.23 Chiasma formation is responsible for generating recombinants. 4.1 Introduction
Parental dNa molecules Introduction 白意意意 Figure 1.24 Recombination intem ediate Recombination involves pairing between complementary strands of the Recom binants two parental bb6Q点b点bbbb6 9露日露白日 duplex dnas 583883 意意白 8意念危意意 消当
Figure 1.24 Recombination involves pairing between complementary strands of the two parental duplex DNAs. 4.1 Introduction