2.4 Telomere:Compositionoftelomere?Thespecialized structurelocatedattheendofchromosome It is rich in short tandem repeated DNA sequences, e.g. “TTAGGG" in humans(端粒DNA序列）Functions:·Ensurethereplicationoftheendsofchromosomes.?腐蚀·Protect them from erosion (nuclease digestion).·PreventthemfromfusionwithotherDNAfragments（维持chr.完整性和独立性）人类染色体端粒DNA的荧光原位杂交照片
人类染色体端粒DNA的荧光原位杂交照片 2.4 Telomere: The specialized structure located at the end of chromosome. It is rich in short tandem repeated DNA sequences, e.g. “TTAGGG” in humans. Functions: • Ensure the replication of the ends of chromosomes. ? • Protect them from erosion (nuclease digestion). • Prevent them from fusion with other DNA fragments. (维持chr.完整性和独立性) Composition of telomere? 腐蚀 （端粒DNA序列）
Il. Three functional elements of chromosome DNA(keysequences)(Plasmid DNA)INTERPHASEMITOSISINTERPHASEtelomereTelomereDNAsequencereplicationAutonomouslyreplicatingoriginDNA sequenceCentromereDNAsequencecentromereportionofmitoticspindleduplicatedreplicationchromosomesbubblein separatecells
II. Three functional elements of chromosome DNA Autonomously replicating DNA sequence Centromere DNA sequence (key sequences) （Plasmid DNA） Telomere DNA sequence
1.Autonomously replicatingDNA sequence (ARS):“复制起始点（质粒）”(Ori)Structure:conservedregions-200bp+200bp11-14bp(AT-rich) ?启动DNA复制Function:ARSactasanoriginofreplication.2.CentromereDNA sequence(CEN): Structure:2 core regions80-90bp AT区11bp保守区Function:Ensure that chromosomes are equally distributed to two daughter cells
1. Autonomously replicating DNA sequence (ARS): Structure: -200bp 11-14bp +200bp (AT-rich) ？ “复制起始点(质粒)” 2. Centromere DNA sequence (CEN): 80-90bp AT区 11bp保守区 Structure: 2 core regions Function: Ensure that chromosomes are equally distributed to two daughter cells. Function: ARS act as an origin of replication. 启动DNA复制 conserved regions (Ori)