Genetic Engineering Biotechnology. History of Genetic Engineering. Before technology, humans were using the process of selective breeding to produce the type of organism they want. Creating new breeds of animals & new crops to improve our food. Example: Dog Breeding. Labradoodle.
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History of Genetic Engineering • Before technology, humans were using the process of selective breeding to produce the type of organism they want. • Creating new breeds of animals & new crops to improve our food.
Example: Dog Breeding Labradoodle Bullmastiff + = Labrador Poodle + = Bulldog Mastiff
Breeding food plants • “Cabbage family” descendants of the wild mustard Evolution of modern corn
Selective Breeding • Choosing individuals with the desired traits to serve as parents for the next generation.
Graph: Plant Height Now, suppose only the tallest plants were used to breed • What is the result? • The frequency of desired alleles increases in the population
Test Cross A? A special cross use to determine an unknown genotypeof a dominant phenotype Cross the unknown individual with a homozygous recessiveindividual
Let’s work this out! Outcome: If the individual is homozygous dominant 100% dominant phenotype If the individual is heterozygous dominant 50% dominant phenotype 50% recessive phenotype
Genetic Engineering • Scientists can now use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules.
Remember the code is universal • Since all living organisms… • use the same DNA • use the same code book • read their genes the same way
Can we mix genes from one organism to another? YES! Transgenic organisms contain recombinant DNA
Recombinant DNA- made by connecting fragments of DNA from a different source. Transgenic Organisms- Organisms that contain DNA from a different source.
How do we do mix genes? • Genetic engineering • Isolate gene from donor DNA • cut DNA in both organisms • paste gene from one organism into other organism’s DNA • transferrecombined DNA into host organism • organism copies new gene as if it were its own • organism produces NEW protein coded for by the foreign DNA Remember: we all use the same genetic code!
Cutting DNA • RESTRICTION ENZYMESare proteins that act as “molecular scissors”
Restriction Enzymes • Restriction enzymesare proteins that cut DNA • Each restriction enzyme only cuts a specific nucleotide sequence in the DNA called the recognition sequence
Restriction Enzymes • Recognition sequences are usually palindromes • Same backwards and forwards • Ex. Eco R1 enzyme recognizes:
Restriction Enzymes • Cuts usually leave little single stranded fragments called STICKY ENDS
Restriction Enzymes • If the enzyme cuts right down the middle, the ends are BLUNT
The recognition sequence for the restriction enzyme named EcoRI is CTTAAG Each time EcoRI recognizes the sequence CTTAAG, it cuts between the G & A and then through the middle of the strands This results in DNA fragments that have single-stranded tails called sticky ends
Restriction Enzymes • Pieces can be glued back together using LIGASE
Gene Transfer • During GENE TRANSFER, a gene from one organism is placed into the DNA of another organism • New DNA that is created is called RECOMBINANTDNA. • Example: Human insulin Insulin Bacterial Recombinant DNA
Bacterial Plasmids • Bacteria have small, circular DNA segments called PLASMIDS. • Usually carry “extra info” on them • Plasmids can be used as a VECTOR- object that carries foreign DNA into a host cell
There’s more… • Plasmids • small extra circles of DNA • carry extra genes that bacteria can use • can be swapped between bacteria
transformedbacteria gene fromother organism recombinantplasmid cut DNA vector plasmid How can plasmids help us? • A way to get genes into bacteria easily • insert new gene into plasmid • insert plasmid into bacteria = vector • bacteria now expresses new gene • bacteria make new protein + glue DNA
Bacteria • Bacteria are great! • one-celled organisms • reproduce by mitosis • easy to grow, fast to grow • generation every ~20 minutes
Creation of Recombinant DNA 1. In a lab, plasmid is extracted from bacteria 2. Insulin also extracted from human DNA • **Both gene for insulin and plasmid are cut with same restriction enzyme. Insulin gene (cut from chromosome) Bacterial Plasmid
Transformation 4. The gene is inserted into the plasmid by connecting sticky ends with ligase. 5. Plasmid taken up by bacteria through TRANSFORMATION. 6. Bacteria grows in Petri dish and replicates recombinant DNA insulin human insulin
Creation of Insulin 7. As the bacteria grow and replicate, more and more bacteria are created with the human insulin gene 8. The bacteria read the gene and create insulin for us to use
Transforming plant & animal cells • Bacterial plasmids can also be put into plant and animal cells • The plasmid incorporates into the plant or animal cell’s chromosome Transformed bacteria introduce plasmids into plant/animal cells
Transgenic Organisms • Because the bacteria now has DNA from two species in it, it is known as a TRANSGENIC ORGANISM. • A.K.A. GENETICALLY MODIFIED ORGANISM
Transforming Bacteria Gene for human growth hormone Recombinant DNA Gene for human growth hormone DNA recombination Sticky ends Human Cell Bacterial chromosome DNA insertion Bacteria cell Bacteria cell containing gene for human growth hormone Plasmid
gene fromother organism recombinantplasmid + TRANSFORMATION vector plasmid CLONE growbacteria harvest (purify)protein Grow bacteria…make more transformedbacteria
CLONE – organism with the same genetic make-up (DNA) as another An exact copy Cloning