8.1 Introduction 8.2 Chaperones may be required for protein folding 8.3 Post-translational membrane insertion depends on leader sequences 8.4 A hierarchy of sequences determines location within organelles 8.5 Signal sequences initiate translocation 8.6 How do proteins enter and leave membranes? 8.7 Anchor signals are needed for membrane residence 8.8 Bacteria use both co-translational and post-translational translocation 8.9 Pores are used for nuclear ingress and egress 8.10 Protein degradation by proteasomes

7.1 Introduction 7.2 Codon-anticodon recognition involves wobbling 7.3 tRNA contains modified bases that influence its pairing properties 7.4 (There are sporadic alterations of the universal code) 7.5 tRNAs are charged with amino acids by synthetases 7.6 Accuracy depends on proofreading 7.7 Suppressor tRNAs have mutated anticodons that read new codons 7.8 The accuracy of translation 7.9 tRNA may influence the reading frame

5.1 Introduction 5.2 Transfer RNA is the adapter 5.3 Messenger RNA is translated by ribosomes 5.4 The life cycle of bacterial messenger RNA 5.5 Translation of eukaryotic mRNA 5.6 The 5 end of eukaryotic mRNA is capped 5.7 The 3 terminus is polyadenylated 5.8 Bacterial mRNA degradation involves multiple enzymes

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

2.1 Introduction We can think about mapping genes and genomes at several levels of resolution: A genetic (or linkage) map identifies the distance between mutations in terms of recombination frequencies. A linkage map can also be constructed by measuring recombination between sites in genomic DNA

DNA是遗传物质 DNA为双螺旋 DNA的复制是半保留的 通过碱基配对进行核酸杂交 突变改变了DNA的序列 突变集中于热点 顺反子是单个DNA片断 多重等位基因的种类

分子生物学 Molecular Biology Zhao WANG (王钊), M.D./Pharm.D. School of Life Science Tsinghua University

29.1 Introduction 29.2 Fly development uses a cascade of transcription factors 29.3 A gradient must be converted into discrete compartments 29.4 Maternal gene products establish gradients in early embryogenesis 29.5 Anterior development uses localized gene regulators

28.1 Introduction 28.2 Transforming viruses carry oncogenes 28.3 Early genes of DNA transforming viruses have multifunction oncogenes 28.4 Retroviruses activate or incorporate cellular genes 28.5 Retroviral oncogenes have cellular counterparts 28.6 Ras oncogenes can be detected in a transfection assay 28.7 Ras proto-oncogenes can be activated by mutation at specific positions 28.8 Nondefective retroviruses activate proto-oncogenes 28.9 Proto-oncogenes can be activated by translocation 28.10 The Philadelphia translocation generates a new oncogene 28.11 Oncogenes code for components of signal transduction cascades 28.12 Growth factor receptor kinases can be mutated to oncogenes 28.13 Src is the prototype for the proto-oncogenic cytoplasmic tyrosine kinases 28.14 Oncoproteins may regulate gene expression 28.15 RB is a tumor suppressor that controls the cell cycle 28.16 Tumor suppressor p53 suppresses growth or triggers apoptosis

26.1 Introduction 26.2 Carriers and channels form water soluble paths through the membrane 26.3 Ion channels are selective 26.4 Neurotransmitters control channel activity 26.5 G proteins may activate or inhibit target proteins 26.6 G proteins function by dissociation of the trimer 26.7 Growth factor receptors are protein kinases 26.8 Receptors are activated by dimerization 26.9 Receptor kinases activate signal transduction pathways