1 / 54

Frontiers of Biotechnology

Frontiers of Biotechnology. Manipulating DNA. Scientists use several techniques to manipulate DNA. Restriction Enzymes cut DNA. Why cut DNA? To study specific genes instead of ALL the genes on a chromosome Restriction enzymes act as molecular scissors Recognize specific sequences

muriel
Download Presentation

Frontiers of Biotechnology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Frontiers of Biotechnology

  2. Manipulating DNA • Scientists use several techniques to manipulate DNA

  3. Restriction Enzymes cut DNA • Why cut DNA? • To study specific genes instead of ALL the genes on a chromosome • Restriction enzymes act as molecular scissors • Recognize specific sequences • Some leave “blunt ends” • Some leave “sticky ends”

  4. Restriction Maps show the lengths of DNA fragments • Gel Electrophoresis: a technique that uses an electrical field within a gel to separate molecules by their size • DNA is negatively charged and moves toward the positive pole when the electrical field is applied • Smallest DNA fragments move the fastest • A pattern of bands is formed

  5. Gel Electrophoresis

  6. Polymerase Chain reaction • PCR:technique that produces millions of copies of a specific DNA sequence in just a few hours • Invented by Kary Mullis in 1983

  7. PCR • Uses: • DNA to be copied • DNA polymerase • Plenty of nucleotides A, T, C, and G • Two primers • 3 Step Process: • Separating • Binding • Copying

  8. RFLPs • Restriction Fragment Length Polymorphisms • No two individuals have the same genetic material except identical twins • Restriction enzymes cut at different places, depending on the DNA sequence • The lengths of DNA restriction fragments are different between two individuals

  9. DNA fingerprinting • A DNA fingerprint is a type of restriction map • Representation of parts of a individual’s DNA that can be used to identify a person at the molecular level • Focuses on noncoding regions of DNA, or DNA sequences outside genes

  10. DNA Fingerprinting • DNA sample from: • Blood • Semen • Bone • Hair • …Useful in forensics!

  11. DNA fingerprinting is used for identification • DNA fingerprints and probability • Compare at least 5 regions of the genome

  12. Genetic Engineering • Entire organisms can be cloned • Clone: genetically identical copy of a gene or of an organism • New genes can be added to an organism’s DNA

  13. 4 Basic Steps to Genetic Engineering • 1. Cutting DNA • 2. Making recombinant DNA • 3. Cloning • 4. Screening

  14. Step 1: Cutting DNA • The DNA from the original organism containing the gene of interest is cut by restriction enzymes • Restriction Enzymes: bacterial enzymes that destroys foreign DNA molecules by cutting them at specific sites

  15. Step 1: Cutting DNA • Vector: Any agent, such as a plasmid, that carries the gene of interest into another cell • Plasmid: A circular DNA molecule that is usually found in bacteria and that can replicate independent of the main chromosome

  16. Recombinant DNA • DNA molecules that are artificially created • HOW????? • Created by combining DNA from different sources

  17. Example: Insulin • A protein hormone that controls sugar metabolism • Diabetics cannot produce enough • Must take doses of insulin daily • Before genetic engineering, insulin was extracted from the pancreases of slaughtered cows and pigs and then purified • Today the human insulin gene is transferred to bacteria through genetic engineering • Because the genetic code is universal, bacteria can transcribe and translate the human insulin gene

  18. Step 2: Making Recombinant DNA • DNA fragments from the gene of interest are combined with the DNA fragments from the vector • DNA ligase: an enzyme that bonds the DNA fragments together • The host cell then takes up the recombinant DNA

  19. Step 3: Cloning • Gene Cloning: many copies of the gene of interest are made each time the host cell reproduces • Remember: bacteria reproduce by binary fission, producing identical offspring with the plasmid DNA!

  20. Step 4: Screening • Cells that have received the particular gene are separated from the cells that did not take up the vector with the gene of interest • The cells can transcribe and translate the gene of interest to make the protein coded for the gene

  21. Confirmation of a Cloned Gene • Southern Blot: a technique used to test for the presence of a specific gene

  22. Northern Blot • Similar to a Southern Blot • Uses RNA instead of DNA

  23. Genetic Engineering produces organisms with new traits

  24. Selective Breeding • Allowing only those animals with desired characteristics to produce the next generation • Horses, cats, farm animals, crops

  25. Hybridization • Crossing dissimilar individuals to bring together the best of both organisms • Hybrids: the individuals produced from such crosses • For example, a disease resistant plant and the food producing capacity of another

  26. Inbreeding • The continued breeding of individuals with similar characteristics • Often seen in dogs • Retains characteristics but has risks • Genetically similar individuals could bring together two recessive alleles for a genetic defect

  27. Today…Genetic Engineering

  28. Genetically Engineered Crops • More tolerant to drought • Plants that can adapt to different soils, climates, and environmental stresses

  29. Genetically Engineered Crops • Resistant to biodegradable weedkillerGlyphosate (kills weeds but now doesn’t kill the crop) • Resistant to insects (gene injures the gut of chewing insects)-therefore plant doesn’t need to be sprayed with pesticides

  30. More Nutritious Crops • Improve the nutritious value of many crops • Asia: rice is a staple food • Low in iron an beta carotene • Iron deficient and poor vision • Genetic engineers have added genes to rice from other plants to overcome this deficiency

  31. Potential Problems to GM Crops • Concern that some weeds will become resistant to the weed killer Glyphosate • New weed-control alternatives will have to be implemented

  32. Potential Problems to GM Crops • Nutritional value has been increased in many crops • Crops must be tested to make sure consumers are not allergic to the GM product

  33. Gene Technology: Animal Farming • Farmers added growth hormones to the diet of cows to increase milk production • Growth hormone was extracted from the brains of dead cows • The hormone was introduced into bacteria and added as a supplement to a cow’s diet

  34. Transgenic Animals • Animals that have foreign DNA in their cells • Human genes have been added to farm animals in order to get the farm animals to produce human proteins in their milk

  35. Transgenic Animals • This is complex and cannot be made by bacteria through gene technology • Human proteins are extracted from the animal’s milk and sold for pharmaceutical purposes • Cloning animals: creating herds of identical animals that can make medically useful proteins

  36. Cloning from Adult Animals • The intact nucleus of an embryonic or fetal cell (whose DNA has been recombined with a human gene) is placed into an egg whose nucleus has been removed • The egg with the new nucleus is put in the uterus of a surrogate, or substitute mother and allowed to develop

  37. Cloning from Adult Animals • 1997 Ian Wilmut first successful cloning using differentiated cells from an adult animal • Dolly the sheep

  38. Cloning from Adult Animals • Differentiated cells: cells that have become specialized to become specific cell types • Scientists had thought that embryonic or fetal cells were the only way…wrong!

  39. Cloning from Adult Animals • Mammary cells from one sheep were fused with egg cells without nuclei form a different sheep • The fused cells divided to form embryos, implanted into surrogate mothers • Only one survived the cloning process • Dolly, identical to the sheep that provided the mammary cell

  40. Problems with Cloning • Only a few of the cloned offspring survive for long • Many become fatally oversized • Problems in development

  41. Genomic Imprinting • The right combination of genes are turned “on” and “off” during early development • The egg takes years to develop the genomic imprint • In cloning, the egg divides within minutes

  42. Genomic Imprinting • Reprogramming is not possible in such a short time • Critical errors in development can occur • Because of these technical problems and ethical problems, cloning humans is illegal in most countries

  43. Concerns about genetic engineering • Ethical? • GM crops • Not enough research had been done to see if added genes might cause allergic reactions or have other unknown side effects • Interbreeding with natural plants…what does it mean?

  44. Genomics involves the study of genes, gene functions, and entire genomes • Genomics: The study of genomes, which can include the sequencing of all of an organism’s DNA • Gene sequencing: determining the order of DNA nucleotides in genes or in genomes

  45. The Geography of the Genome • Only 1-1.5% of the human genome codes for proteins • Each human cell contains about 6 feet of DNA • Less than 1 inch are exons

  46. The Geography of the Genome • Human cells contain about 25,000 genes (scientists had expected 120,000!) • Only 2x the number of genes in a fruit fly! • Many human genes are identical to those of other species • All humans are genetically close (DNA of any 2 people is 99.9% identical)

  47. The human genome project • Our genome is relatively small! 3 billion base pairs, but only between 30,000-40,000 genes • Project started in 1990 with 2 main goals: • Map and sequence all of the DNA base pairs of the human chromosomes (accomplished in 2003) • Identify all of the genes within the sequence (still be worked on)

  48. The human microbiome project • 200 scientists at 80 institutions sequenced the genetic material of bacteria taken from nearly 250 healthy people • As many as a thousand bacterial strains on each person. • Each person’s collection of microbes, the “microbiome”, was unique

  49. Technology allows the study and comparison of both genes and proteins • Bioinformatics: the use of computer databases to organize and analyze biological data • DNA microarrays: tools that allow scientists to study many genes, and their expression at once; a small chip dotted with the genes being studied • Proteomics: the study and comparison of all the proteins that result from an organism’s genome

More Related