2 Chapter Mystery A case of mistaken identity Page 417Hypothesis: How did the police know they had the wrong suspect?
3 Section 15.1 Selective Breeding Objectives:What is selective breeding used for ?How do people increase genetic variation?Define:Selective breedingHybridizationInbreedingbiotechnology
4 I. Selective Breeding Dogs = Chihuahua Great Dane Humans bred dogs for 1000s of years looking to produce better hunters, retrievers, companionsSelective breeding – allowing only those animals with wanted characteristics to produce the next generationHumans use selective breeding, which takes advantage of naturally occurring genetic variation, to pass wanted traits on to the next generation of organismsProduced new varieties of cultivated plants and all domestic animals (horses, cats, cows) by selectively breeding for particular traitsNative Americans selectively bred teosinte (wild grass) to produce corn = more nutritious and productive
5 A. HybridizationLuther Burbank (1849 – 1926) – developed >800 varieties of plantsHybridization – crossing dissimilar individuals to bring together best of both organismsHybrids – individuals produced by crossesOften hardier than either of parentsBurbank’s crosses combined disease resistance of one plant w/ food-producing capacity of anotherResults in new line of plants that had traits farmers needed to increase food production
6 B. InbreedingInbreeding – continued breeding of individuals with similar characteristicsUsed to maintain desirable characteristics in a line of organismsHelps ensure that characteristics that make each breed unique are preservedCan be riskyMost members of a breed = genetically similarIncreases chance that a cross b/w 2 individuals will bring together 2 recessive alleles for genetic defect
7 II. Increasing Variation Breeders can increase the genetic variation in a population by introducing mutations, which are the ultimate source of biological diversityBiotechnology – application of a technological process, invention, or methodUsed when manipulate genetic makeup of an organismSelective breeding = one form (important in agriculture and medicine)
8 A. Bacterial Mutations Mutations – heritable changes in DNA Occur spontaneouslyCan be increased by breeders by using radiation or chemicalsMany harmful to organismWith luck and perseverance breeders can produce a few mutants w/ useful characteristics not found in original populationUseful in bacteriaSmallMillions can be treated w/ radiation/chemicals at same time = increases chance of producing a useful mutantScientists have produced 100s of useful bacteriaSome consume oil (oil spills)Working on bacteria that can clean up radioactive substances and metal pollution in environment
9 B. Polyploid PlantsDrugs that prevent separation of chromosomes during meiosis = useful in plant breedingProduce cells that have many times normal number of chromosomesPlants grown from these cells = polyploid b/c they have many sets of chromosomesPolyploidy – usually fatal in animals; plants much better at tolerating extra sets of chromosomesCan quickly produce new species of plants: larger and stronger than diploid relativesBananas, citrus fruits
10 Section 15.2 Recombinant DNA Objectives:How do scientists copy the DNA of living organism?How is recombinant DNA used?How can genes from one organism be inserted into another organism?Define:Polymerase chain reactionRecombinant DNAPlasmidGenetic markerTransgenicClone
11 I. Copying DNA In the past – mutations unpredictable Today – genetic engineers can transfer certain genes at will from one organism to another = new living thingsDNA extracted from cells cut into fragments separated according to size find DNA of single gene among 3 million fragments!!!!
12 Mystery CluePage 421…How could restriction enzymes be used to analyze the DNA evidence found on the suspect?
13 A. Finding Genes 1987 – Douglas Prasher – jellyfish wanted to find gene that codes for green fluorescent proteinGFP – absorbs energy from light & makes jellyfish parts glowWanted to link GFP to when a protein was being made in a cellTo find the gene using mRNA and radioactive probes to bind to complementary base sequences
14 B. Polymerase Reaction Chain Heat piece of DNA separates strandsAs DNA cools, primer binds to single strandsDNA polymerase starts copying region b/w primersCopies serve as templates to make more copies
15 II. Changing DNA Wondered how to change DNA of living cell Griffith answered transformation: cell takes DNA from outside cell, added DNA becomes component of cell’s own genomeHeat-killed bacteria contained DNA fragmentsWhen mixed w/ live bacteria some took up fragments transformed bacteria (changed characteristics
16 A. Combining DNA Fragments Today – can build custom DNA molecules with genes you like & insert them into living cellsRecombinant DNA technology – joining together DNA from 2 or more sourcesMakes it possible to change the genetic composition of living organismsCan investigate the structure and function of genes
17 B. Plasmids and Genetic Markers Scientists join recombinant DNA to another piece of DNA containing a replication “start” signal whenever cell copies its own DNA, it copies recombinant DNA tooPlasmid – small circular DNA moleculeJoin DNA to plasmid use recombinant plasmid to transform bacteria results in replication of newly added DNA w/ rest of cell’s genomeGenetic marker – gene that makes it possible to distinguish bacteria that carry the plasmid from those that don’tUsed to locate transformed cells
18 III. Transgenic Organisms Transgenic – contain genes from other speciesTransgenic organisms can be produced by the insertion of recombinant DNA into the genome of a host organism1980’s – perfected using miceNow – plants, animals, microorganismsContributes to understanding gene regulation and expression
21 C. CloningClone – member of a population of genetically identical cells produced from a single cellUse single cell from adult organism to grow an entirely new individual that is genetically identical to organism from which cell was taken1952 – 1st clone of animals – amphibian tadpoles1997 – Ian Wilmut – cloned sheep “Dolly”Since = cloned cows, pigs, mice, cats
22 Section 15.3 Applications of Genetic Engineering Objectives:How can genetic engineering benefit agriculture and industry?How can recombinant-DNA technology improve human health?How is DNA used to identify individuals?Define:Gene therapyDNA microarrayDNA fingerprintingforensics
23 I. Agriculture and Industry Everything we eat and much of what we wear come from living organismsUse genetic engineering to try to improve products from plants and animalsIdeally, genetic modification could lead to better, less expensive, and more nutritious food as well as less-harmful manufacturing processes.
24 A. GM CropsIntroduced 19962007 – GM crops = 92% soybeans; 86% cotton; 80% corn grown in USUse bacterial genes that produce protein (Bt toxin)Harmless to humansEnzyme in insects converts Bt toxin into a form that kills the insectNo pesticides needed & produce higher yield of cropsResistance to herbicides (chemicals that destroy weeds)Resistance to viral infectionsProduce foods resistant to rot and spoilage (soon)Produce plastics for manufacturing industry (soon)
25 B. GM Animals Food supply Hope to clone transgenic animals 30% milk from cows injected w/ hormones made by recombinant-DNA techniques to increase milk productionPigs – produce more lean meat or high levels of healthy omega-3 acidsSalmon – growth hormone = grow more quickly (grown in captivity)Spider genes into goats = manufacture silk w/ milk extracted & woven into thread = light, tough, flexible material (military uniforms, medical sutures, tennis racket strings)Human genes + goat milk = antibacterial goat milkHope to clone transgenic animalsIncrease food supplySave endangered species2008 – US gov’t approved sale of meat and milk from cloned animals
26 II. Health and Medicine Biotechnology = part of medicine Early physicians – extracted substances from plants and animals to cure patients20th century – vaccination saved countless livesToday – recombinant-DNA technology source of some of most important advances in prevention and treatment of disease
27 A. Preventing Disease Golden rice – incr. provitamin A + beta-carotene Hope to help prevent health problems (infant blindness)Transgenic plants/animals to make human antibodiesFuture transgenic animals may supply us w/ human proteins used in disease preventionAlready produced in milk of some transgenic sheep and pigs
28 B. Medical Research Transgenic animals – used as test subjects Simulate human diseases caused by defective genesUse models based on simulations to follow onset and progression of diseases & test new drugs that may treat diseaseEx: Alzheimer’s & arthritis
29 C. Treating DiseaseRecombinant-DNA technology make important proteins that could prolong or save human livesHuman growth hormone – used to treat pituitary dwarfism now widely available b/c mass produced in recombinant bacteriaInsulin – treat diabetesBlood-clotting factors – hemophiliaInterleukin-2 & interferon – cancer (future)
30 Gene therapy – process of changing a gene to treat a medical disease/disorder Absent or faulty gene is replaced by a normal, working geneAllows body to make the protein/enzyme needed eliminates cause of disorderHuman Genome ProjectHow it works:Engineer virus that cannot reproduce or cause harmful effectsPut DNA w/ therapeutic gene into modified virusInfect patient’s cells w/ virusIn theory: virus will insert healthy gene into target cell and correct defectChallenge: deliver gene that works correctly over long termHigh risk & experimental procedureTo become accepted treatment need more reliable ways to insert working genes and ensure DNA used does no harm
31 D. Genetic TestingGenetic tests – use specific DNA sequences that detect complementary base sequences found in disease-causing allelesOther tests – search for changes in cutting sites of restriction enzymesSome – use tests to detect differences b/w length of normal and abnormal allelesAvailable for diagnosing hundreds of disorders
32 E. Examining Active Genes All cells in human body contain identical genetic materialSame genes not active in every cellDNA microarray technology – used to study 100s/1000s of genes at once to understand levels of gene activity
33 III. Personal Identification Complexity of human genome = no individual is exactly like any other geneticallyDNA fingerprinting analyzes sections of DNA that may have little or no function but that vary widely from one individual to anotherDNA samples from blood, sperm, tissue, hair w/ root
34 A. Forensic Science Used since 1980s Precise & reliable Forensics – scientific study of crime scene evidenceDNA fingerprinting – solve crimes, convict criminals, overturn wrongful convictionsWildlife conservation – identify herds from which black-market ivory was taken (elephants in Africa)
35 B. Establishing Relationships DNA fingerprinting disputed paternity: alleles in child not carried by mother must come from fatherY chromosome – never crosses over=few changes (father to child)miDNA (mitochondrial)- small so few changes (mother to child)
36 Mystery CluePage 434…What kind of evidence do you think investigators collected at the crime scene?What kinds of tests would they have to run on this evidence?What would the tests have to show before the suspect was released?
37 Section 15.4 Ethics and Impacts of Biotechnology Objectives:What privacy issues does biotechnology raise?Are GM foods safe?Should genetic modifications to humans and other organisms be closely regulated?Assignment 2-column Chart & Essay:Write both viewpoints for each issue in this section to help you create a view point for each question aboveWrite your opinion answer for each question above… use support from the reading that is now in your chart
42 Solve the Mystery Page 443… How did the investigators determine that the person they took into custody was not guilty of this crime?Did the DNA evidence from the bloodstains come from the red blood cells, white blood cells, or both? EXPLAIN.What if the initial suspect was related to the victim? Would that have changed the result? Why or why not?What might have happened if this crime were committed before DNA fingerprinting was discovered? Describe the series of events that might have taken place after police took in the first suspect.