Genetic Engineering Ch 15

1. Genetic EngineeringCh 15 “Real World Biology”

2. Ch 13-1 Changing the Living World • Selective Breeding • People select organisms with desired characteristics to produce next generation • Takes advantage of naturally occurring variation Selective breeding of teosinte grass by native Americans 6000 years ago led to corn as we now know it

3. Selective Breeding • Hybridization • Cross dissimilar organisms to bring together best of both organisms • Ex: disease resistance + increased yield • Benefits include hardier plants • American botanist Luther Burbank developed more than 800 varieties of plants using selective breeding methods.

4. Selective Breeding • Inbreeding • Breeding a line of organisms with similar characteristics • Ex: dog breeds • Risks- decreased genetic variation and increased susceptibility for certain diseases/disorders • Ex: hip dysplasia

5. Selective Breeding: Ligers • http://www.bing.com/videos/search?q=ligers&view=detail&mid=5F109EBB5D6E6243677C5F109EBB5D6E6243677C&first=0&FORM=NVPFVR&adlt=strict

6. Increasing Variation • Process used to increase the variation normally present in nature • But why? • Biotechnology is the application of a technological process, invention, or method to living organisms.

7. Increasing variation • Can be accomplished through mutations • Mutations are usually random, but can be induced via radiation and chemical exposure • Potential to yield few beneficial mutants with desirable characteristics not found in original population

8. Increasing Variation • Bacteria- can treat millions at a time increasing chances of producing useful mutants • Ex: oil-digesting bacteria

9. Increasing Variation • Plants-arresting chromosome separation during meiosis to produce polyploids • Known to be more vigorous than diploid relatives

10. 13-2 Manipulating DNA • Mutations are random • Having a way to alter DNA in a very specific way to achieve a particular result has huge advantages • Scientists can now use the knowledge of DNA structure and its chemical properties to study and change DNA molecules

11. Tools of Molecular Biologists • Genetic engineering allows biologists to rewrite the DNA code of an organism • Modern techniques employed can • Extracting DNA from cells • Cutting it into smaller pieces • Identifying sequences of bases in DNA (genes) • Making unlimited copies

12. Finding Genes • Started with Douglas Prasher (1987) • Prasher wanted to find a specific gene in a jellyfish that codes for a molecule called green fluorescent protein, or GFP • GFP is a natural protein that absorbs energy from light and makes parts of the jellyfish glow • Prasher thought that GFP from the jellyfish could be linked to a protein when it was being made in a cell • bit like attaching a light bulb to that molecule

13. Finding Genes (GFP specifically) • Prasher compared part of the amino acid sequence of the GFP protein to a genetic code table • was able to predict a probable mRNA base sequence that would code for this sequence of amino acids • Then used a complementary base sequence to “attract” an mRNA that matched his prediction and would bind to that sequence by base pairing. • After screening a genetic “library” with thousands of different mRNA sequences from the jellyfish, he found one that bound perfectly

14. Finding Genes • To find the actual gene that produced GFP, Prasher took a gel in which restriction fragments from the jellyfish genome had been separated and found that one of the fragments bound tightly to the mRNA • That fragment contained the actual gene for GFP • This method is called Southern blotting, after its inventor, Edwin Southern.

16. These mice are glowing because scientists inserted a gene found in certain bioluminescent jellyfish into their DNA. That gene is a recipe for a protein that glows green when hit by blue or ultraviolet light. The protein is present throughout their bodies. As a result, their skin, eyes and organs give off an eerie light. Only their fur does not glow.

17. Finding Genes- Southern Blot Analysis

18. Finding Genes • Today it is often quicker and less expensive for scientists to search for genes in computer databases where the complete genomes of many organisms are available.

19. Richard Resnick: Welcome to the Genomic Revolution • http://www.ted.com/talks/richard_resnick_welcome_to_the_genomic_revolution.html • In this accessible talk from TEDxBoston, Richard Resnick shows how cheap and fast genome sequencing is about to turn health care (and insurance, and politics) upside down.

20. Copying DNA (specific genes) • First step is a polymerase chain reaction (PCR) • Heat a piece of DNA • separates its two strands • DNA cools and added primers bind to the single strands • DNA polymerase starts copying the region between the primers • These copies can serve as templates to make still more copies.

21. Polymerase Chain Reaction • Once biologists find a gene, a technique known as polymerase chain reaction (PCR) allows them to make many copies of it. • 1. A piece of DNA is heated, which separates its two strands.

22. Polymerase Chain Reaction • 2. At each end of the original piece of DNA, a biologist adds a short piece of DNA that complements a portion of the sequence. • These short pieces are known as primers because they prepare, or prime, a place for DNA polymerase to start working.

23. Polymerase Chain Reaction • 3. DNA polymerase copies the region between the primers. These copies then serve as templates to make more copies. • 4. In this way, just a few dozen cycles of replication can produce billions of copies of the DNA between the primers.

24. Copying DNA • It is relatively easy to extract DNA from cells and tissues. • The extracted DNA can be cut into fragments of manageable size using restriction enzymes. • These restriction fragments can then be separated according to size, using gel electrophoresis or another similar technique

25. Gel Electrophoresis • http://learn.genetics.utah.edu/content/labs/gel/http://learn.genetics.utah.edu/content/labs/gel/ http://learn.genetics.utah.edu/content/labs/gel/

26. Recombinant DNA Technology It is a form of genetic engineering that cleaves DNA into small fragments and inserts those fragments into a host organism • Host may be the same or a different species

28. Transgenic Organisms • Organisms who have incorporated foreign DNA in their chromosomes and use this new DNA as their own

30. Mr. Green Genes • http://www.youtube.com/watch?v=k_Z6M3mDt9Q&safe=active

31. How to Produce a Transgenic Organism • Step 1: Isolate the gene in the foreign DNA that you want to insert • Ex: isolate the gene for beta carotene in a daffodil so you can then add it to rice

32. Step 2: Cut it out of the chromosome (in daffodil) using restriction enzymes. • Restriction enzymes are bacterial proteins that have the ability to cut both strands of the DNA molecule at a specific nucleotide sequence • Resulting fragments can have blunt ends or sticky ends

33. In biology, sticky end and blunt end are the two possible configurations resulting from the breaking of double-stranded DNA. DNA exhibits a stabilizing interaction between complementary base pairs, providing specificity to the pairing of two strands of DNA. If two complementary strands of DNA are of equal length, then they will terminate in a blunt end, as in the following example: 5'-CpTpGpApTpCpTpGpApCpTpGpApTpGpCpGpTpApTpGpCpTpApGpT-3' 3'-GpApCpTpApGpApCpTpGpApCpTpApCpGpCpApTpApCpGpApTpCpA-5' However, if one strand extends beyond the complementary region, then the DNA is said to possess an overhang: 5'-ApTpCpTpGpApCpT-3' 3'-TpApGpApCpTpGpApCpTpApCpG-5' If another DNA fragment exists with a complementary overhang, then these two overhangs will tend to associate with each other and each strand is said to possess a sticky end: 5'-ApTpCpTpGpApCpT pGpApTpGpCpGpTpApTpGpCpT-3' 3'-TpApGpApCpTpGpApCpTpApCpGp CpApTpApCpGpA-5' becomes 5'-ApTpCpTpGpApCpT pGpApTpGpCpGpTpApTpGpCpT-3' 3'-TpApGpApCpTpGpApCpTpApCpGp CpApTpApCpGpA-5'

34. Some Commonly used REs • EcoRI (eco r one) • HindIII (hindi three) • BamHI (bam h one) • TaqI (tack one)

35. Step 3: Cut host’s DNA with the same RE so cut ends will match up • When DNA from two different organisms joins up- recombinant DNA is formed

37. Vectors • Getting DNA from one organism into another requires a vector • The vector introduces the new DNA into the host cell • Bacterial DNA is often used as a vector

38. Bacterial DNA • Bacteria contains plasmids- small rings of DNA separate from the bacterium’s larger circular chromosome • The foreign DNA is inserted into the plasmid by cleaving both using the same restriction enzyme • Sticky ends match up and foreign DNA becomes part of plasmid

39. Gene Cloning • Plasmid with foreign DNA (Now considered recombined DNA) is inserted into a bacterial cell • Plasmids can replicate within the cell and can produce up to 500 copies in the cell

40. Soon Tons of Copies! • Bacteria clones the recombinant DNA • Clones-genetically identical copies How? • Bacterial cells themselves will reproduce quickly, each with hundreds of copies of the recombinant DNA inside (plasmid + foreign DNA)

42. Introduction into Host Cell • Plasmid is then inserted into a host’s chromosome where it will be replicated each time the cell replicates along with the organism’s other chromosomes • The host cell can transcribe/translate that recombinant DNA into protein just like all other proteins coded in its DNA

44. Cloned Coyotes • http://www.youtube.com/watch?v=x0EGgymKh3A&safe=active

46. South Korean scientist Hwang Woo-Suk (L) and Vasily Vasiliev (R), vice director of North-Eastern Federal University of Russia's Sakha Republic, exchange agreements during a signing ceremony on joint research at Hwang's office in Seoul. The research collaboration agreement will help Russian and S.Korean scientists to recreate a woolly mammoth which last walked the earth some 10,000 years ago

49. Should we clone Neanderthals??? • A U.S. scientists says we are now capable of cloning a Neanderthal baby by introducing Neanderthal genome material into a human stem cell and implanting it into a surrogate mother. The theory is, cloning a Neanderthal would increase human diversity and show us new ways of thinking or even curing disease.But what of the moral and legal issues?

50. Ellen Jorgensen: Biohacking -- You can do it too • http://www.ted.com/talks/ellen_jorgensen_biohacking_you_can_do_it_too.html • We have personal computing, why not personal biotech? That’s the question biologist Ellen Jorgensen and her colleagues asked themselves before opening Genspace, a nonprofit DIYbio lab in Brooklyn devoted to citizen science, where amateurs can go and tinker with biotechnology.