医学专业英语课件_15.pptx

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1、Making babies:Genetically CorrectZhi Hua RanThe department of Gastroenterology Ren Ji Hospital A Glossary of Genetics TermsGene:basic unit of inheritance for all living organismsGenome:Genetic endowment of a speciesGene mapping:Determining location of genes on chromosomeGene sequencing:Determining i

2、dentity of genes from the distinctive order(sequence)of base pairs,such as A-T and G-CChromosome:Threadlike structure in the nuclei of plant and animal cells;it carries the linearly arranged genetic units(genes)A Glossary of Genetics TermsNucleic acid:Large,chainlike molecule of phosphric acid,sugar

3、 and purine and pyrimidine basesMarker:Gene with a known location on a chromosomeTemplate:Macromolecular model for another macromolecule,as in the synthesis of RNA from a DNA templateTransgenic:Organism,such as a mouse,containing experimentally transferred genetic material from another organism,such

4、 as mammalMutation:Abrupt change in the genotype of an organism that is not the result of recombination A Glossary of Genetics TermsRecombination:Formation in offspring of genetic combinations not present in parentsGenotype:The genetic constitution of an individualPhenotype:The observable characters

5、 of an organism;the result of the way the genes are expressedGenetic defect:Pathological changes that occur by duplication,deletion or rearrangement of DNATranscription:The process by which RNA is formed from DNANucleotide:The structural unit of nucleic acid A Glossary of Genetics TermsRT-PCR:Revers

6、e transcriptase polymerase chain reaction Gene therapy:A technique for correcting defective genes responsible for disease development DNA microarray:An experimental tool for obtaining high-throughput gene expression data Stem cell:have the remarkable potential to develop into many different cell typ

7、es in the body.Serving as a sort of repair system for the body,they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive.When a stem cell divides,each new cell has the potential to either remain a stem cell or become another type of cell with

8、 a more specialized function,such as a muscle cell,a red blood cell,or a brain cell.Milestones of GeneticsDiscover the double-helix structure of DNA-by James Watson and Francis CrickMapping the human genome-The Human Genome Project,completed in 2001Create the first recombinant DNA molecule-by Paul B

9、erg Discover the DNA structure1953-James Watson/Francis CrickDouble-helix structure of DNA Biography-James Watson Born in Chicago,April 6,1928 His fathers ancestors were originally of English descent His mothers father was Scottish-born taylor married to a daughter of Irish immigrants who arrived in

10、 the US about 1840Spent entire boyhood in Chicago Biography-James Watson Study at University of Chicago at 1943In 1947,received a B.Sc.degree in Zoology During these years,his boyhood interest in bird-watching had matured into a serious desire to learn geneticsHis Ph.D thesis was a study of the effe

11、ct of hard X-rays on bacteriophage multiplicationIn 1950,received Ph.D degree in Zoology at Indiana University Biography-James Watson In the spring of 1951,he change his direction of his research toward the structural chemistry of nucleic acids and proteinsMet Crick at 1952,common interest in solvin

12、g the DNA structureSolved in early March,1953-the proposal of the complementary double-helical configuration19531955 at the California Institute of Technology as Senior Research Fellow in Biology 1956,Assitant Professor,Harvard Biology Department1958,Associate Professor1961,Professor Biography-James

13、 Watson 1962,The Nobel Prize in Physiology or MedicineBorn on June 8,1916 at Northampton,EnglandIn 1937,obtained a B.Sc.In Physics at LondonDuring the war,he worked as a scientist for the British Admiralty Biography-Francis CrickLeft the Admiralty in 1947 to study biologyStarted to learn biology in

14、1937,interrupted by World War TwoJoined the Medical Research Council Unit since 1949Restarted in 1950,obtained Ph.D in 1954 Biography-Francis Crick1962,The Nobel Prize in Physiology or MedicineDied at 2004Worked out the general theory of X-ray diffraction by a helixBorn on June 30,1926,New York Biog

15、raphy-Paul BergBest known for his development of a technique for splicing together DNA from different types of organisms.His achievement gave scientists a tool for studying the structure of viral chromosomes and the biochemical basis of human genetic diseases.Gained early recognition/influence when

16、he delineated the key steps in which DNA produces proteinsAwarded the Nobel Prize for Chemistry in 1980 The Human Genome ProjectBegan at 1990Draft sequence was published in 2001Founded by US department of Energy(DOE),US National Institute of Health(NIH)in collaboration with Britains Wellcome trust T

17、he Human Genome ProjectCelera Genomics,a private company based in Maryland,is publishing its findings in Science.Human have about 30,000 genes A public international effort,led by the United States,is publishing its analysis of the genome in Nature,a British journal.Genetic differences between any t

18、wo people are relatively small The Human Genome Project-more powerful toolsDurg development,customizing drugs to individual genetic profilesEarlier diagnosis of disease In Vitro Fertilization-historyThe technique was developed in the UK by Dr.Patrick Steptoe and Robert EdwardsFirst “test tube“baby:I

19、n UK,Louise Brown(July,1978The first in US:Elizabeth Carr by Dr.Howard and GS Jones(1981)Second “test tube“baby:In India,Kanupriya Agarwal by Dr.Mukhopadhyay(Oct,1978)Since then,IVF has exploded in populatiry,accournts 1%of all birth,115,000 in total in US The first“test-tube“baby In Vitro Fertiliza

20、tion-historyLouise Brown born in England in July 25,11:47 PM,197825 y1y With parents In Vitro Fertilization-historyOldham General HospitalDr.Patrick SteptoeDr.Robert EdwardsAt birth In Vitro FertilizationThe first phase consists of stimulating the ovary with hormones injected,in order to cause sever

21、al eggs to matureNormally,only one egg matures per menstrual cycle,so additional hormones are usually required to prevent the body from negatively to this excess of eggsPhase 1:The last injection given is that of human chorionic gonadotropin(hCG),the hormone normally produced during pregnancy In Vit

22、ro FertilizationThe second phase,that of egg retrieval,occurs about 34-36 hours after the hCG injectionThe entire procedure usually takes8-20 minsPhase 2:In Vitro FertilizationThe third phase involves fertilization of the eggsPhase 3:ICSI-Intracytoplasmic sperm injection123 In Vitro FertilizationPha

23、se four is the actual embryo replacementA pregnancy test usually is done 12-14 days after retrievalPhase 4:2 Cell embryo4 Cell embryo8 Cells embryo Thumbing through the encyclopedia of lifeTechnology often drives science,science drives medicine,and medicine is always pushing society in to ethical co

24、rnersDr.Mark Hughes Prenatal Genetic AnalysisOne of the ethically most problematic applications of geneticsIf detected in the fetus,are incurable,may lead to selective abortionPrenatal diagnosis of genetic traits typically can only provide information to assist the prospective parents in their decis

25、ion making whether to carry the pregnancy to term or to terminate it Prenatal Genetic AnalysisIt requires both a medical indication and informed conset of the parentsParents have a right to refuse medically indicated prenatal diagnosis even if there is a high risk for fetal condition that is incompa

26、tible with lifeThere are a few genetic traits(such as gender)are accessible to prenatal diagnosis today but unrelated to health Prenatal Genetic AnalysisPrenatal diagnosis is carried out only to give parents and physicians information about the health of the fetusThe use of prenatal diagnosis for pa

27、ternity testing,except in cases of rape or incest,or for gender selection,apart from sex-linked disorders,is not acceptableWHO 1998 Prenatal Genetic AnalysisHeterozygosity testing for recessive disease could only be attempted for eugenic purposesGregor Mendel 18221884Mendels law of independent assor

28、tment孟德儿独立分配定律Mendels law of segregation孟德儿分离定律 Novel parameters for prenatal selection-gene testingCarrier screening,which involves indentifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the diasese to be expressedPreimplantation genetic diagnosi

29、s(screening Embryos for disease)Newbone screening Presymptomatic testing for predicting developing adult-onset disorders such as Huntingtons diseasePresymptomatic testing for estimating the risk of developing adult-onset cancers and Alzheimers diseaseConfirmational diagnosis of a symptomatic individ

30、ualForensic/identity testingGene testing-HDHuntingtons disease(HD):Usually midlife onset;progressive,lethal,degenerative neurological diseaseCaused by a single abnormal geneAn autosomal dominant disorder Gene testing-SMAOne of the neuromuscular diseases.Muscles weaken and waste away(atrophy)due to d

31、egeneration of motor neurones which are nerve cells in the spinal cord Gene was located Proximal portion of the long arm of chromosome 5,1990Gene testing-Fanconi SyndromeA disorder in which the proximal renal tubules of the kidney do not properly reabsorb electrolytes and nutrients back into the bod

32、yExcessive drinking,urination and glucose in the urineMuscle wasting,acidosis and poor condition will also occur Pre-implantation diagnosisSingle cell analysisTechnology:RT-PCR Technology-RT-PCRElectrophoresis DNA microarray Gene therapyA normal gene may be inserted into a nonspecific location withi

33、n the genome to replace a nonfunctional gene.This approach is most commonAn abnormal gene could be swapped for a normal gene through homologous recombinationThe abnormal gene could be repaired through selective reverse mutation,which returns the gene to its normal functionThe regulation of a particu

34、lar gene could be alteredDr.Mark HughesA Professor and Director of Molecular Medicine and Genetics at Wayne State University and Director of the Genomics Center Hub for the State of Michigans Life Sciences Corridor.His work has centered on understanding gene expression in the early human embryo He p

35、ioneered the field of PGD for couples at very high reproductive genetic risk and offers this technology in conjunction with IVF Centers in the U.S.and Canada.Bypassing the natrual method of conceptionDiscarding excess embryosContributes to overpopulationEthical challengesCreating life in the laborat

36、oryFertilizing more embryos than will be neededUnnatural environment for embryosPotential to select embryosPotential to modify embryosEthical challengesPotential to creat embryos for medical purposesAlteration of genetic traits:Beauty/handsome,longevity,healthyPotential to modify embryosA girl or boy,you pick?Potential to select embryosWe can test for lots of things,the question is,should we?-Dr.Mark HughesEthical challenges