g8 ribosomal rna keywords ribosome 核糖体cluster 成簇 .ppt

* G8 RIBOSOMAL RNA Keywords ribosome 核糖体 cluster 成簇 sedimentation coefficient 沉降系数 spacer DNA 间隔DNA tandemly repeated 串联重复 ribozyme 核酶 upstream control element (UCE) 上游调控元件 upstream binding factor(UBF) 上游结合因子 small nucleolar RNA (snoRNA) 核仁小RNA 1 Ribosomes Each ribosome consists of two subunits, a small subunit and a large subunit. Sedimentation coefficients are usually measured in Svedberg units (S). the overall structure and function of eukaryotic ribosomes is very similar to those of bacteria. Various rRNA are tightly folded and base pair extensively with each other to form the core of ribosomal subunits with the proteins restricted to the surface and filling gaps between RNA folds. 2 Transcription and processing of prokaryotic rRNA seven rRNA transcription units scattered throughout the genome Processing of prokaryotic rRNA 3 Synthesis of eukaryotic 28S, 18S and 5.8S rRNA In eukaryotes, the genes for 28S, 18S and 5.8S rRNA are typically clustered together and tandemly repeated in that one copy each of 18S, 5.8S and then 28S genes occur, followed by untranscribed spacer DNA, then another set of 18S, 5.8S and 28S genes occur and so on. The synthesis of 28S, 18S, and 5.8S rRNA The synthesis of human rRNA methylation endoribonuclease 4 Ribozymes In Tetrahymena (四膜虫), the pre-rRNA molecule contains an intron. In the presence of guanosine (GMP, GDP or GTP), the intron excises itself, ------ self-splicing. Ribozymes, catalytic RNA molecules that catalyze specific reactions. 具有酶促活性的RNA称为核酶。 四膜虫rRNA内含子的二级结构 The ribozymes have hammerhead structure designed ribozyme To be used in the treatment of virus diseases and tumors 底物部分 合成 核酶研究的意义 对中心法则作了补充； 对传统