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Understanding Selective Breeding and Genetic Engineering in Agriculture

This lesson explores the principles of selective breeding and genetic engineering in agriculture. Discover how humans have manipulated DNA and organisms for thousands of years to enhance agricultural output, such as developing disease-resistant crops and livestock. Through methods like hybridization and inbreeding, we ensure desirable traits are passed on, while also understanding the potential risks of genetic mutations. We also delve into recombinant DNA technology and its applications, including creating transgenic organisms and the implications for food production.

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Understanding Selective Breeding and Genetic Engineering in Agriculture

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  1. Lesson Overview 15.1 Selective Breeding Show short videos from Nova

  2. REVIEW • What are the two things that can get mutated (when talking DNA)? • Yes! Genes & Chromosomes • Did you know that some people make MUTATIONS on purpose?

  3. THINK ABOUT IT • Where does • popcorn come from? • Earliest Ex of efforts to select/improve living orgs for our benefit! • Bred teosinte • Popcorn—5000 years old!

  4. 1 of world’s most impt crops!

  5. Selective Breeding • Breeding to pass on traits they want (done for 1000s of years) • Examples: • Farm animals, dogs, horses, crop plants (corn, soybeans, cotton) • Why? • Produce “disease or pesticide resistant” • “bigger”, “better” heartier species • Less land/energy, no chems & CHEAPER! Types of GMF's

  6. 2 Methods 1. Hybridization: Crossing dissimilar individuals to bring together both of their best characteristics • Ex: • Plant 1: Has disease resistance • Plant 2: High food-producing capacity • RESULT: A new line of plants for farmers & consumers! • Luther Burbank (800 new plant varieties)

  7. 2 Methods 2. Inbreeding:Maintains desired characteristics using similar organisms & develops pure lines. • Example: • Pure Bred DOGS • AKC • RISK? • May bring 2 recessive alleles for a genetic defect. • Blindness • Joint deformities

  8. Increasing Variation… • HOW? • By using radiation and chemicals (> rate) • Creates a few desirable mutants • RISK? • Possibly be very harmful to an animal • Can create non-desirable mutants!

  9. Biotechnology • Application of a technologicalprocess, invention, or method to living orgs.

  10. Polyploid Plants • Larger/Stronger • Drugs prevent separation of chroms. during meiosis • Many times normal # of chroms.

  11. Lesson Overview 15.2 Recombinant DNA

  12. THINK ABOUT IT • Suppose you have an video game you want to change. • So…the game depends on a “coded program” in a computer microchip • You’d need a way to get existing program out of microchip, read program, make changes you want, and put modified code back into microchip. • What does this have to do with genetic engineering? Just about everything.

  13. Copying DNA • How do scientists copyDNA of living orgs? • It is relatively easy to extract DNA and cut into fragments (Using ___________enzymes)

  14. DNA is Extracted using Gel Electrophoresis

  15. Finding Genes • Douglas Prasher, MASS. Biologist (1987) • Jelly Fish Story (GFP-Green Flourescent Protein) Gets E from light to glow, add GFP gene (attaching light bulb to molecule)

  16. Luciferase & Luciferin combine with ATP

  17. Tobacco plant with firefly genes genesgenes

  18. Polymerase Chain Reaction (PCR) • Once biologists find a gene, PCR allows them to make many copies (4 steps). • 1. DNA heated (2 strands). • 2. Primer (short piece of DNA) added to each end • 3.DNA polymerase copies between primers (templates) • 4. Billions of DNA copies

  19. Is it possible to change the DNA of a living cell? • Griffith did it w/bacterial transformation…

  20. Scientists can produce custom-built DNA molecules in lab & insert into living cells • Recombinant-DNA technology—joining together DNA from 2+ sources (using DNA ligase)

  21. Plasmids & Genetic Markers • Some bacteria contain small circular DNA molecules (plasmids) • Put recombinant DNA into ring of DNA

  22. Plasmid DNA Transformation Using Human Growth Hormone

  23. Transgenic Organisms • “Containing genes from other species” • Orgs produced by insertion of recombinant DNA into genome of host

  24. Transgenic Plants: Transforming a Plant with Agrobacterium

  25. Gene Therapy(How to get the “cool” gene!) • 1. Isolate foreign DNA fragment to be inserted • Use “restriction enzymes” to CUT DNA out • Like zipper (but only at certain spots-SNP) • 2. Attach DNA fragment to Vector (carrier) • viruses & plasmids • 3. Transfer into host organism • Cells “cloned” w/ normal mitosis Do play w/ Rest. Enz., Org 1, Host Or & Vector

  26. The Liger…. 52:21 to 56:49 on Spy Kids II

  27. Cloning Animals—Nuclear Transplantation

  28. Cloning • *Genetically IDENTICAL cells produced from a SINGLE cell. • Nuclear Transplantation (1st remove egg’s nucleus) • 1952-Amphibian Tadpoles • 1997-Wilmut: Cloned an adult cell (Dolly) who created Bonnie & triplets. • Cows, pigs, mice, etc. Plants/bacteria easy.

  29. Cloning • Reason: Hoping for medical/scientific value • Pro • Help save endangered species • Cure diseases • Make duplicate organs and prized animals • Create people/animals w/o certain diseases • Con • Problems are unknown! • If cloning humans, is this morally “right”?

  30. Lesson Overview 15.3 Applications of Genetic Engineering

  31. THINK ABOUT IT • Have you eaten any GM food lately? • 86% Corn, potatoes, or soy products 2008 meat/milk, 100% chance, eat/wear,

  32. Agriculture and Industry • Genetic modification could lead to food: • 1. better (Ex: Insect Resistance/Herbicide Tolerance) • 2. less expensive • 3. more nutritious & • 4. less harmful manufacturing processes.

  33. GM Crops

  34. What ELSE? • Cows- 30% U.S. milk w/hormones • Pigs-leaner meatw/ omega-3 acids. • Salmon-growquickly! • Goats-Produce silk(spider genes) in milk . • Golden rice-vitamin A • Sheep/pigs milk produce human proteins (easy to collect/refine)

  35. Treating Disease • Substances mass-produced by recombinant genetically-engineered (GE) bacteria • Human Growth Hormone • Insulin • Blood-clotting factors • Interleukin-2 and Interferon

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