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Genetic engineering and selective breeding
EQ: How can you use genetic engineering and selective breeding to produce desired traits?
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Genetic Engineering and Selective breeding
Genetic Engineering involves identifying certain genes and moving them from one organism to another – even to a different species or removing the gene entirely! Selective Breeding involves choosing two organisms of the same species and mating them with the hope of getting the best qualities of each parent to show up in the offspring.
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Genetic engineering Taking DNA from one organism and inserting it into another organism’s DNA sequence, ensures the organism will have a specific trait. It produces an organism that has a new trait it would most likely not have developed on its own
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Genetic Engineering Step 1: Identify desired gene
Step 3: Remove undesired genes Step 4: Insert desired gene Step 2: Use enzymes to cut desired genes loose
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Genetic engineering Diabetic = a person whose pancreas cannot create the important hormone insulin. Take the gene for making insulin from a healthy donor’s DNA Add that gene to the DNA of pancreas cells from a diabetic Let mitosis happen for a while (in a “test tube”) so you get LOTS of pancreas cells with the good gene. Surgically implant the good cells back into the diabetic Give the insulin gene to diabetics.
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Genetic engineering Make chickens with no feathers.
Scientists engineered chickens to be featherless by REMOVING the gene in chicken DNA that causes them to grow feathers
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Genetic engineering Cabbage plant + scorpion venom = bug-proof veggies Scientists added a gene for producing scorpion venom to cabbage plants to kill pesky caterpillars that eat the crops!
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Genetic Engineering Give tomatoes the ability to make anti-freeze.
Placing the “anti-freeze gene” from a cold-water fish in tomatoes, so the tomatoes can still grow in cold weather.
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Genetic engineering Remember! Genetic engineering involves the manipulation of genes!
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Genetic Engineering Costly
Advantages Disadvantages Will get improved organisms Can create organisms with traits not previously thought possible Can remove “bad” genes Reduces the chance of getting “undesirable” organisms Costly Must be performed in a lab with special equipment Ethical issues Long term negative affects Negative environmental impacts
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Genetic engineering Genetic engineering has few limits - except our imagination, and our moral or ethical code. What might go wrong if genetic engineering is used in an immoral or unethical way? If dinosaurs can make a comeback again, how do animals ever become extinct? What is stopping scientists from re-creating extinct animals and reintroducing them back into our ecosystems? What conclusion can you reach after watching this clip and our class discussion?
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Genetic engineering and selective breeding
EQ: How can you use genetic engineering and selective breeding to produce desired traits?
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Selective breeding Selective breeding involves mating organisms with different “desirable” traits to get offspring with the desirable traits of both parents Parents must be of the same species! No ligers, llamacorns, etc Selective breeding is used mostly for dogs, cats, other pets, cattle, and crops.
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Selective breeding Tough Boar + meaty pig = Superpig
Tough wild boars mated with friendly meaty pigs give you robust & meaty pigs for your farm.
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hot weather cow + beefy cow = supercow
Selective breeding Brahman cattle: Good resistance to heat, but poor beef. English shorthorn cattle: Good beef but poor heat resistance Santa Gertrudis cattle (cross of 2 breeds) hot weather cow + beefy cow = supercow RESULT = good beef and resistant to heat!
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Selective breeding Choosing only the best corn plants for seeds results in better crops over a long time.
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little red tomato + big green = BIG RED TOMATO
Selective breeding little red tomato + big green = BIG RED TOMATO
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Selective breeding Selective breeding crosses organisms of the same species with desirable traits to produce offspring that have the traits from both parents!
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Selective breeding Advantages Disadvantages
Might get improved organisms Don’t need any special tools or lab Can be performed easily by farmers & breeders Undesirable traits from both parents may appear in the offspring Disease can accumulate in the population You may end up with deaf dalmatians, boxers with heart disease, labs with hip problems…
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Flipping Puppies: A genetics simulation game
EQ: How could you use genetic engineering and selective breeding to produce desired traits in an organism?
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Congratulations! You and your partner have opened a new business breeding Basset hound puppies. However, being educated and ethical business people, you know that you must learn all about this breed before starting to breed and sell your pups. One issue you learned about Basset hounds as you researched is a condition known as Bassett Hound Thrombopathia (BHT)
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Bassett Hound Thrombopathia
BHT is a blood clotting disease found in Basset hounds. This genetic disease causes excessive bleeding in affected dogs, which are homozygous recessive (tt) for the traits. However, many Basset hounds are carriers . They don’t have the disease, but are heterozygous (Tt) for the gene and can pass it to their offspring. Reputable dog breeders (like yourself) use genetic counseling to eradicate genetic diseases. They use Punnett Squares and pedigrees to determine affected dogs and carriers.
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Procedures You have opened your new business breeding Basset hound puppies. No puppies in the litter from which you purchased your new male puppy have BHT, but unfortunately, their father did Look at the blank Punnett/pedigree sheet. What genotype is the father? How do we know? What is the mother’s phenotype and genotype? How do we know? Write the mother’s genotype on the circle representing her. Would you darken the circle on the pedigree? Why or why not? On the Punnett square for the Parental Generation, fill in the alleles and work the cross.
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Procedures Record your puppy’s genotype on the pedigree, below the male square for the first generation, F1. Would you darken the square? Why or why not? Now, fill in the male puppy’s alleles on the top portion of the F1 Generation Punnett. Congratulations! You just purchased a female puppy! Toss the coin to find out her alleles. Heads = dominant (T), Tails=recessive (t) You will need to flip twice : once for allele #1, then for allele #2 Write in your female alleles on the side portion of the F1 Generation Punnett, and write the genotype below the F1 circle on the pedigree. Shade the circle as necessary. Work the F1 Generation cross. Notice the boxes for the F1 Generation Punnett are numbered To pick the male puppy moving on to the F2 Generation, roll the die and use the numbered box you roll (if you roll a 5 or 6, re-roll) Repeat the above directions for each generation until you reach the F7 Generation Answer the EVALUATE questions on the back **If both the male and the female genotype is tt, you have no more puppies to breed and you are out of business!
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Evaluate (Back of sheet. Answers only)
How successful was your puppy business? How might you improve it? What are the advantages and disadvantages of breeding purebred animals? In what ways can reducing genetic diversity affect a species? In what way would breeding your purebred with another breed reduce the occurrence of BHT? Would genetic engineering be appropriate in this situation?
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Assignment EQ: How could you use genetic engineering and selective breeding to produce desired traits in an organism?
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The Assignment Assignment Scenario
Design a poster to promote or dissuade the use of either selective breeding or genetic engineering Scenario You are a geneticist. After studying both selective breeding and genetic engineering you have formed a strong opinion (pro or con) on one of these issues. You want to make your opinion known to the public so that they have the information needed to form their opinion on your passion. To do so, you must make your opinion accessible, cheap to produce and easy to distribute. You have decided to design a poster either to promote or dissuade the use of either selective breeding or genetic engineering
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Procedures Make a choice --- choose to focus on either genetic engineering OR selective breeding Make a choice (again) – are you FOR your chosen procedure or are you against it? Create a snappy tag line to bring in the public Add 3-4 concise, supporting statements to solidify your tag line Draw a simple picture(s) that ties your ideas together
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