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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.

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Presentation on theme: "Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece."— Presentation transcript:

1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 14 DNA Technology and Genomics

2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: Understanding and Manipulating Genomes Sequencing of the human genome was largely completed by 2003 DNA 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: _guide_p1a.shtml _guide_p1a.shtml

3 LE 20-2 Bacterium Bacterial chromosome Plasmid Gene inserted into plasmid Cell containing gene of interest Gene of interest DNA of chromosome Recombinant DNA (plasmid) Plasmid put into bacterial cell Recombinant bacterium Host cell grown in culture to form a clone of cells containing the “cloned” gene of interest Protein expressed by gene of interest Protein harvested Gene of interest Copies of gene Basic research on gene Basic research on protein Basic research and various applications Gene for pest resistance inserted into plants Gene used to alter bacteria for cleaning up toxic waste Protein dissolves blood clots in heart attack therapy Human growth hor- mone treats stunted growth

4 LE 20-3 Restriction site DNA Restriction enzyme cuts the sugar-phosphate backbones at each arrow. One possible combination DNA fragment from another source is added. Base pairing of sticky ends produces various combinations. Fragment from different DNA molecule cut by the same restriction enzyme DNA ligase seals the strands. Recombinant DNA molecule Sticky end

5 LE 20-7 Primers New nucleo- tides PCR – 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.

6 LE 20-8 Cathode Power source Anode Mixture of DNA molecules of differ- ent sizes Gel Glass plates Longer molecules Shorter molecules

7 LE 20-9 Normal  -globin allele 175 bp201 bpLarge fragment Sickle-cell mutant  -globin allele 376 bpLarge fragment Ddel Ddel restriction sites in normal and sickle-cell alleles of  -globin gene Normal allele Sickle-cell allele Large fragment 376 bp 201 bp 175 bp Electrophoresis of restriction fragments from normal and sickle-cell alleles RFLP – restriction length polymorphisms. Mutations that can be detected to see if you have disease causing alleles.

8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

9 Future 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.

10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Human Gene Therapy Gene 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 gene Vectors are used for delivery of good genes into cells – like viruses which can easily fit receptors. Retroviruses make a DNA copy with the gene Gene therapy raises ethical questions, such as whether human germ-line cells should be treated to correct the defect in future generations

11 LE Cloned gene Retrovirus capsid Bone marrow cell from patient Inject engineered cells into patient. Insert RNA version of normal allele into retrovirus. Viral RNA Let retrovirus infect bone marrow cells that have been removed from the patient and cultured. Viral DNA carrying the normal allele inserts into chromosome. Bone marrow

12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animal Husbandry and “Pharm” Animals Transgenic organisms are made by introducing genes from one species into the genome of another organism Transgenic animals may be created to exploit the attributes of new genes (such as genes for faster growth or larger muscles)

13 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Several organisms have similar genes that can be transferred between them. Ex: homeotic genes

14 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Genetic Engineering in Plants Agricultural scientists have endowed a number of crop plants with genes for desirable traits The 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…

15 LE Agrobacterium tumefaciens Ti plasmid Site where restriction enzyme cuts DNA with the gene of interest T DNA Recombinant Ti plasmid Plant with new trait

16 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cloning – 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

17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings SNP – 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.


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