细胞器 医学分子生物学.ppt

比错义突变的疾病表型更具有系统性特征，且所有生物合成基因突变都为tRNA突变，并与线粒体肌病相关。主要有MERRF综合征(癫痫伴碎红纤维病) (MIM 545000)。 2. 蛋白质生物合成基因突变 线粒体DNA的突变类型 (一) 碱基突变 1. 错义突变 mtDNA缺失突变引起绝大多数眼肌病，这种缺失导致的疾病一般无家族史。 线粒体DNA的突变类型 2. 蛋白质生物合成基因突变 (一) 碱基突变 1. 错义突变 (二) 缺失、插入突变 线粒体DNA的突变类型 2. 蛋白质生物合成基因突变 (一) 碱基突变 1. 错义突变 (二) 缺失、插入突变 (三) mtDNA拷贝数目突变： 致死性婴儿呼吸障碍 乳酸中毒或肌肉、肝肾衰竭 Leber遗传性视神经病(LHON) Leber遗传性视神经病是被证实的第一种母系遗传的疾病，至今尚未发现一个男性患者将此病传给后代。 LHON是以德国眼科医生Theodor Leber的名字命名的，为一种急性或亚急性发作的母系遗传病。男女病人比例5:1。 11778G→A导致编码NADH脱氢酶亚单位4(ND4)中第340位的Arg精→His组，从而影响线粒体能量的产生。 Leber遗传性视神经病(LHON) 11778 G→A MERRF综合征 MERRF综合征是一种罕见的、杂质性的母系遗传病。 典型为8344 bp突变，即MTTK*MERRF8344G，导致tRNALys改变，使蛋白质合成受阻。 8344 bp The Cytoskeleton Cytoskeleton is a network of protein filaments in the cytoplasm Main functions: Supports large volume of the cytoplasm. Participates in large-scale movements associated with the changes in cell shape and cell motility. Provides machinery for organelle transport, chromasome segregation during mitosis, and cell division. Actin filaments Microtubules Intermediate filaments Major components of cytoskeleton The cytoskeletal filaments Common Features : Linear polymers of protein subunits Actin ( ~8 nm in diameter) Intermediate Filaments ( ~10 nm in diameter) Microtubules ( ~24 nm in diameter) Filaments are dynamic, i.e. they can assemble and disassemble Highly conserved Intermediate Filaments Intermediate filaments enable cells to withstand mechanical stress when cells are stretched. They can span the entire cytoplasm and are anchored to the plasma membrane. The Microtubule Cytoskeleton Also penetrates the entire volume of the cell Whereas actin fibers are concentrated at the periphery, most microtubules radiate from a central location in the cell Main functions: intracellular transport and mitosis Microtubules provide an organizational structure in an interphase cell and separate chromosomes in a dividing cell /external/Frank.Gibbons/spindle.html Microtubules Microtubules Provide Tracks for Transport Mi