2 Genetic variation How are a great dane and a chihuahua similar? All dogs are the same speciesLOTS of genetic variation!How did this happen?We did it!
3 Selective breedingSelective breeding: a method of breeding organisms with desired characteristics to provide the next generation with that traitTakes advantage of natural genetic variationLuther Burbank- selectively bred disease-resistant potatoes
4 hybridizationHybridization: breeding technique that crosses dissimilar individuals to bring together the best traits of eachHybrid: offspring of hybridizationEx: crossing a large sized potato with a potato that is disease-resistantOr a hybrid car……or a mule!
5 inbreedingInbreeding: continued breeding of individuals with similar (desired) characteristicsYou get the desired traits but…Increased chance of other defects (ex: 2 recessive alleles)
6 Genetic variationIncreased genetic variation = possibility of breeding mutants (but this is a good thing)Remember the 4 criteria for a gene?Mutations are the BIGGEST source of genetic variationWhether good or bad, mutations are new to a population and increase diversity
7 Producing new kinds of organisms Treat with radiation or chemicals to mutateBacteriasmall and multiply quick/easy to pass along mutationEx: bacteria that digest oil (used in oil spills)PlantsChemicals prevent chromosome separation in meiosisEnd up with extra sets of chromosomes (polyploids)
8 13-2 Manipulating DNA What does it mean to “manipulate” DNA? To change it!Selective breeding and inbreeding use natural genetic variation…but its unpredictable!Now, we can “rewrite” the code
9 How do we change dna?Must have knowledge of structure and chemical propertiesNew technology:1. extraction techniques2. cut into smaller pieces3. identify base sequences4. make unlimited copies
10 1. Dna extraction Like in our strawberry lab! Open up the cell and nucleusSeparate DNA from everything else
11 2. Cutting dna…Restriction enzymes: enzyme that cuts DNA at a specific sequence of nucleotidesVery specificRecombinant DNA: DNA produced by combining DNA from different sourcesEx: human insulin gene and pig DNA- have pigs produce insulin
12 …and separating DNAGel electrophoresis: procedure used to separate + analyze DNA fragmentsPlace DNA (- charge) at one end of a gel and apply + charge to the otherFragments move across gel- smaller move faster/furtherUsed to compare/contrast/identify particular genes
13 3. Identifying base sequences Used to study specific genes, compare, discover functions, etc.To “read” the sequence = determine the order of basesSequencing:Start with unknown strand + DNA polymerase +nucleotide bases = complimentary strand is madeBases are dyed to identify themNow, everything is automated
14 4. Making copiesPolymerase chain reaction (PCR): technology that allows scientists to make many copies of a geneHow it works:Heat DNA- strands separateCool and add primers- short pieces of DNA that tell DNA polymerase to start workingAdd free nucleotide bases + DNA polymeraseMakes a new stand- like artificial DNA replication!
15 13-3 cell transformation What is transformation? Taking in DNA from outside the cell- this “external” DNA then becomes part of the new cell’s DNADNA MUST be integrated into a chromosome!Recombinant DNA!
16 Transforming bacteria Plasmid: small circular DNA moleculeWhy plasmids?Replicate easily so foreign DNA will then be replicatedGenetic marker: a gene that distinguishes bacteria with foreign DNA plasmid from ”regular” bacteriaAntibiotics resistant genes used alot
17 Transforming plant cells Use bacterium that inserts a plasmid with manipulated foreign DNA into plant cellsCan also:Take up DNA when cell wall is removedInject DNA directly into plant cellsEither way, DNA MUST be integrated into the chromosome
18 Transforming animal cells Cells are large enough for direct injection of DNAEnzymes used to cut and insert DNA into chromosomeMay also use genetic markersGene replacement- replace one gene with another
19 13-4 Applications of ge GE = biotechnology Can we combine plant and animal genes?YES!Luciferase enzyme (firefly glow) + tobacco plant = a glowing plant
20 Transgenic organismsTransgenic organism: an organism that contains genes from a different organismGene from one inserted into the cell of anotherThese transformed cells = a new organism!
21 Transgenic microorganisms Insert human gene for proteins into bacteriaBacteria used to “harvest” human proteinsEx: insulin, growth factors, clotting factors
22 Transgenic plants Examples: Plants with natural insecticides Plants that will resist weed-killing chemicalsRice with added vitamin A
23 Transgenic animals For research: mice with human immune systems For food:Livestock with added growth hormone- grow faster/leanerChicken that is resistant to food poisoning bacteriaMilk that produces human proteins in it
24 cloningClone: a member of a population of genetically identical cells produced from a single cellSingle-celled bacteria= easy to cloneMulticellular organism= more difficult“Dolly” the sheep- cloned by Ian Wilmut in 1997
25 How did he do it? De-nucleate an egg cell Donor nucleus fuses to the de-nucleated cellFused using an electric shockCell will begin to divide- form an embryoEmbryo is placed in foster mom’s uterusDevelopment and birth happen as normally does