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医用分子遗传学. 本课程主要包括分子遗传学的基本原理以及现代基因工程和蛋白质工程及其在医学中的应用。 要求同学能够掌握基因表达与调控、基因工程和蛋白质工程、基因诊断和基因治疗的基本理论和方法。 考核方式:闭卷考试 负责教师:于 敏( minyu@shmu.edu.cn) 魏欢欢( weiyh@fudan.edu.cn ) 教科书:医用分子遗传学(复旦大学出版社) 教学参考书: Robert F. Weaver 分子生物学( Molecular Biology )科学出版社( McGraw-Hill ). 第一章 重组 DNA 技术- 基因工程 及其与医学的关系.
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医用分子遗传学 • 本课程主要包括分子遗传学的基本原理以及现代基因工程和蛋白质工程及其在医学中的应用。 • 要求同学能够掌握基因表达与调控、基因工程和蛋白质工程、基因诊断和基因治疗的基本理论和方法。 • 考核方式:闭卷考试 • 负责教师:于 敏(minyu@shmu.edu.cn) 魏欢欢(weiyh@fudan.edu.cn) • 教科书:医用分子遗传学(复旦大学出版社) • 教学参考书:Robert F. Weaver分子生物学(Molecular Biology)科学出版社(McGraw-Hill)
第一章 重组DNA技术-基因工程及其与医学的关系 复旦大学分子医学教育部重点实验室 于 敏 2011.9.
Warming up • DNA Recombination • Gene Engineering • Application of Gene Engineering in Medical Science
Warming up - Basic facts of RNA and DNA
Central Dogma of Molecular Biology Reverse Transcription
DNA and Protein Electrophoresis • Agarose gel electrophoresis • Polyacrylamide gel electrophoresis (PAGE)
Gel Electrophoresis A technique used to separate DNA fragments by size The gel (agarose or polyacrylamide) is subjected to an electrical field The DNA, which is negatively-charged, migrates towards the positive pole The larger the DNA fragment, the slower it will move through the gel matrix DNA is visualized using fluorescent dyes 12
I. Recombinant DNA cloning technology DNA cloning Applications in enzymology Hybridization DNA Sequencing Polymerase Chain Reaction(PCR )
1. DNA cloning • To obtain large amounts of pure DNA • Procedure • Isolate DNA • Use restriction enzymes to cut DNA • Ligate fragments into a cloning vector • Transform recombinant DNA into a host to replicate the DNA and pass copies into progeny.
DNA Manipulation The molecular biology revolution started with the discovery of restriction endonucleases Enzymes that cleave DNA at specific sites These enzymes are significant in two ways 1. Allow a form of physical mapping that was previously impossible 2. Allow the creation of recombinant DNA molecules (from two different sources)
Molecular Cloning A clone refers to a genetically identical copy Molecular cloning is the isolation of a specific DNA sequence (usually protein-encoding) Sometimes called gene cloning The most flexible and common host for cloning is E. coli Propagation of DNA in a host cell requires a vector
Vectors Plasmids are small, circular extrachromosomal DNA molecules Used for cloning small pieces of DNA Have three important components 1.Origin of replication 2.Selectable marker 3.Multiple cloning site (MCS)
Vectors Phage vectors are modified bacterial viruses Most based on phage lambda (l) of E. coli Used to clone inserts up to 40 Kbp Have two features not shared with plasmid vectors They kill their host cells They have linear genomes Middle replaced with inserted DNA
2. Applications in enzymology • Restriction endonucleases • DNA polymeraseⅠ • Reverse transcriptase • DNA ligase • Alkaline phosphatase • Terminal transferase • Taq DNA polymerase
GGATCC CCTAGG Restriction endonuclease It can recognize special sequences and cleave DNA at these specific base sequences. Type II can recognizepalindrome sequences.
Palindrome • Palindrome is also called inverted repeat sequence, which means the nucleotide sequence in 5′to 3′direction is the same in both strands.
Palindrome(回文序列) 客上天然居, 居然天上客。 僧游云隐寺, 寺隐云游僧 。 Madam, I'm Adam. Was it a car or a cat I saw?
Restriction Enzymes • Recognize a specific DNA sequence (restriction site) • Break a phosphodiester linkage between a 3’ carbon and phosphate • Used for • Create DNA fragments for cloning • Analyze positions of restriction sites in cloned or genomic DNA
Restriction Enzymes • Are found naturally in bacteria as a defense against vital DNA. • Restriction sites are methylated in bacteria, and thus protected. • Are denoted by three letter names derived from the bacterial strain they originate from.
Restriction Enzymes: EcoRI • EcoRI (“Echo R one”) is a commonly used enzyme. It was the first (one) restriction enzyme isolated from the “R” strain of E. coli. It demonstrates the usual type recognition site, a palindrome (the same on both strands, reading in opposite directions) EcoRI leaves a four base, 5’overhang, sticky end.
Restriction Enzyme Sites • Sma I (from Serratia marcescens) cuts a palindrome to give blunt ends. • BamHI (from Bacillus amyloliquefaciens H) cuts to give a 5’ overhang. • PstI (from Providencia stuartii) cuts to give a 3’ overhang.
Restriction Enzymes • Blunt ends: both strands are cut at the same position. • Sticky ends: overhanging regions (3’ or 5’) are useful in cloning. They are complementary, thus anneal, DNA ligase can covalently link them.
Restriction Enzyme Analysis of Cloned DNA sequences • Cloned DNA can be cut with restriction enzymes and electrophoresed on agarose gels and visualized with ethidium bromide, in order to map its restriction sites • DNA cut with several enzymes, each loaded in a lane of an agarose gel.
Restriction enzyme analysis of cloned DNA sequences • DNA is stained with ethidium bromide, which fluoresces under UV when complexed with DNA. The gel is photographed, and the distance migrated by each band of identical DNA molecules is measured and compared with a calibration curve. • Restriction mapping may be done with a circular plasmid, a cloned sequence, or a fragment of plasmid prepared by gel cutting.
Ligation of DNA • Ligation of sticky end • DNA ligase • Ligation of blunt ends • DNA ligase • Alkaline phosphatase • The addition of a homopolymer tail • DNA ligase • Terminal transferase
4. DNA Sequencing • Dideoxy Method • Automated DNA Sequencing