Transcript Slide 1
Recombinant DNA Technology Human insulin monomer The Principle DNA Highly stable and relatively easy to manipulate. RNA Degrades quickly. Protein The biologically active material that is needed. Impossible to synthesize artificially and difficult (expensive) to purify from natural sources. What we can do…. • Precisely detect and amplify very small amounts of DNA and RNA (just a few copies will work) • Rapidly determine sequence whether known or unknown • Recombine (cut and paste) sequences together or deliberately change (mutate) them. • Express genes in virtually any organism at any level using recombinant DNA plasmids and viruses So what is all this good for? • Biological products can be produced for medical reasons. • Organisms can be genetically modified to fit specific needs. • Individuals can be rapidly screened for syndromes, diseases, and side effects. • Treatment for individuals with genetic syndromes/diseases • Crime solving/identification Microarray (Genomics) Gene chips Screen 13,000 genes at once! Can be used to rapidly identify disease conditions. Restriction Mapping Genetic screening Forensics Forensics 1 2 3 FROM BLOOD AT CRIME SCENE 4 5 6 7 Reverse transcription and/or PCR amplification GOI or DNA product cut with same restriction enzyme as vector Manipulating DNA Transcription promoter Selectable gene (antibiotic resistance) Recombinant DNA products can be produced in cultured tissue cells (bioreactors) or in animals and plants (“Pharming”) A Specific Case—Human Insulin • A large complex molecule • Virtually absent in type 1 diabetics • Originally purified from bovine or porcine tissues • Difficult to purify, low activity • Recombinant human insulin generated in bacteria. Transgenics Animals and plants can also be genetically altered for desirable characteristics such as herbicide resistance. Risks.. Environmental impact Human health Fig. 16.13a, p. 263 Gene Therapy Transgenic humans Therapeutic potential Gene Therapy’s Growing Pains • How do you get the gene where you need it? – Remove tissue (bone marrow), modify, replace – Viral vectors (adenovirus and retrovirus vectors) – Liposomes (lipid spheres) • How do you get the gene to express correctly? – Therapy of limited duration (in practice) • Remember insertional mutagenesis? – Do no harm! • Immune rejection and other complications – First human death from gene therapy in 1999. Bioethics • Patient “Informed Consent” – Do they really understand the risks? • Can a gene be “owned”? – How about a modified gene? • Environmental impact of bioengineering? • Right to genetic privacy? • Bioengineering of human beings?