Presentation on theme: "DNA Technology and Genomics"— Presentation transcript:
1DNA Technology and Genomics Chapter 14DNA Technology and Genomics
2Overview: Understanding and Manipulating Genomes Sequencing of the human genome was largely completed by 2003DNA sequencing has depended on advances in technology, starting with making recombinant DNA. Many are disappointed cures have not been found.What organisms have been sequenced? Look here:
3LE 20-2 Bacterium Cell containing gene of interest Gene inserted into plasmidBacterialchromosomePlasmidGene ofinterestRecombinantDNA (plasmid)DNA ofchromosomePlasmid put intobacterial cellRecombinantbacteriumHost cell grown in cultureto form a clone of cellscontaining the “cloned”gene of interestGene ofinterestProtein expressedby gene of interestCopies of geneProtein harvestedBasic research andvarious applicationsBasicresearchon geneBasicresearchon proteinGene for pestresistance insertedinto plantsGene used to alterbacteria for cleaningup toxic wasteProtein dissolvesblood clots in heartattack therapyHuman growth hor-mone treats stuntedgrowth
4One possible combination Recombinant DNA molecule Restriction siteDNA5¢3¢3¢5¢Restriction enzyme cutsthe sugar-phosphatebackbones at each arrow.Sticky endDNA fragment from anothersource is added. Base pairingof sticky ends producesvarious combinations.Fragment from differentDNA molecule cut by thesame restriction enzymeOne possible combinationDNA ligaseseals the strands.Recombinant DNA molecule
5LE 20-7PCR – polymerase chain reaction. Making millions of copies of a portion of DNA to test. Thanks to bacteria from Yellowstone(with a heat stable DNA poly) – the reason forensics has evolved, sequencing the mammoth, Neanderthal etc.. We will do this on you!! 3 parts – heat DNA slightly to separate, cool so primers can bond, DNA poly adds nucleotides to 3” ends.PrimersNewnucleo-tides
6LE 20-8 Mixture of DNA Longer molecules molecules of differ- Cathode ent sizesLongermoleculesCathodeShortermoleculesPowersourceGelGlassplatesAnode
7LE 20-9 Normal b-globin allele 175 bp 201 bp Large fragment Ddel Ddel Sickle-cell mutant b-globin allele376 bpLarge fragmentDdelDdelDdelDdel restriction sites in normal and sickle-cell alleles of-globin geneNormalalleleSickle-cellalleleLargefragment376 bp201 bp175 bpElectrophoresis of restriction fragments from normaland sickle-cell alleles RFLP – restriction length polymorphisms. Mutations that can be detected to see if youhave disease causing alleles.
9Future Directions in Genomics Genomics is the study of entire genomes. Same gene can make different proteins by splicing introns at different places!!How do we know what a gene does? Knock it out and see what the consequences are.Gene targeting is often used to inactivate single genes. Such gene 'knockout' experiments have elucidated the roles of numerous genes in embryonic development, adult physiology, aging and disease. To date, more than ten thousand mouse genes (approximately half of the genes in the mammalian genome) have been knocked out. Ongoing international efforts will make 'knockout mice' for all genes available within the near future.
10Human Gene TherapyGene therapy is the alteration of an afflicted individual’s genes – like sickle cell.Gene therapy holds great potential for treating disorders traceable to a single defective geneVectors are used for delivery of good genes into cells – like viruses which can easily fit receptors. Retroviruses make a DNA copy with the geneGene therapy raises ethical questions, such as whether human germ-line cells should be treated to correct the defect in future generations
11LE 20-16 Cloned gene Insert RNA version of normal allele into retrovirus.Viral RNALet retrovirus infect bone marrow cellsthat have been removed from thepatient and cultured.RetroviruscapsidViral DNA carrying the normalallele inserts into chromosome.Bonemarrowcell frompatientBonemarrowInject engineeredcells into patient.
12Animal Husbandry and “Pharm” Animals Transgenic organisms are made by introducing genes from one species into the genome of another organismTransgenic animals may be created to exploit the attributes of new genes (such as genes for faster growth or larger muscles)
13Several organisms have similar genes that can be transferred between them. Ex: homeotic genes
14Genetic Engineering in Plants Agricultural scientists have endowed a number of crop plants with genes for desirable traitsThe Ti plasmid is the most commonly used vector for introducing new genes into plant cells. Plants can produce a toxin from a bacteria, so when a caterpillar eats the leaf – its stomach explodes. Plants can also be “Round-up” resistant, so the weeds die from it but not the plants. Many plants world wide are now GMO’s – golden rice (w/ vitamin A for blindness) strawberries, tomatoes, corn etc…
16Cloning – entire organism. A way to bring back or prevent extinctions? Take DNA from a host cell (skin, hair) suck out DNA from an egg and put new DNA in.Implant in a surrogate mother (must be related enough to not reject embryo). Wait until birth.Dolly and many mammals have been cloned. Problems with disease and aging due to methylation of older DNA?? Genes not turning on as they do in infancy. Conclusion – clone in mammals not identical, not same personality
17SNP – single nucleotide polymorphism Spot where 1 base pair differs in at least 1% of the population. It’s a stable mutation so it helps track ancestry.