分子生物学（杨君）lecture1 Welcome to Molecular Biology.pptVIP

Chargaff’s Ratio Tetranucleotide hypothesis: DNA was made up of equal quantities of the four bases (by P.A. Levene,1920s). Chargaff’s rule: the content of purines was always roughly equal to the content of pyrimidines. Erwin Chargaff （1905-2002） 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 Chargaff Chargaff’s observation disproved the tetranucleotide hypothesis; the four bases of DNA did not occur in a 1:1:1:1 ratio. His results gave insight to Watson and Crick in the development of their model DNA Model 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 Crick is best known for his work in the discovery of the double helix, but since then he has made many other discoveries. established the basic genetic code predicted the mechanism for protein synthesis Proposed the Central dogma Adaptor (RNAs) hypothesis In 1960, Crick began to study the structure and possible functions of certain proteins associated with chromosomes called histones. 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 One of the great founder of Molecular Biology The central dogma（中心法则, 1953-1956 ） describes the basic nature of genetic information: sequences of nucleic acid can be perpetuated（不朽的） and interconverted（互换） by replication（复制）, transcription（转录）, and reverse transcription（反转录）, but translation（翻译） from nucleic acid to protein is unidirectional（单向的？）. Genetic information can be provided by DNA or RNA 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 DNA RNA Protein Replication Transcription Translation RNA as Genetic Material Plants infected by TMV develop characteristic mosaic（嵌花式）-like lesions（损害） on their leaves. 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 Reconstituted TMV in vitro 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 A retrovirus（逆转录病毒） is an RNA virus with the ability to convert its sequence into DNA by reverse transcription. Reverse transcription is synthesis of DNA on a template of RNA. It is accomplished by the enzyme reverse transcriptase. Retrovirus（逆转录病毒） 课程内容 1 导言 小 结 知识回顾 课程介绍 教师介绍 Updated Information about Central Dogma Reverse Transcription RN