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Presentation on theme: "Chapter 13 GENETIC ENGINEERING."— Presentation transcript:


2 Genetic variation How are a great dane and a chihuahua similar?
All dogs are the same species LOTS of genetic variation! How did this happen? We did it!

3 Selective breeding Selective breeding: a method of breeding organisms with desired characteristics to provide the next generation with that trait Takes advantage of natural genetic variation Luther Burbank- selectively bred disease-resistant potatoes

4 hybridization Hybridization: breeding technique that crosses dissimilar individuals to bring together the best traits of each Hybrid: offspring of hybridization Ex: crossing a large sized potato with a potato that is disease-resistant Or a hybrid car… …or a mule!

5 inbreeding Inbreeding: continued breeding of individuals with similar (desired) characteristics You get the desired traits but… Increased chance of other defects (ex: 2 recessive alleles)

6 Genetic variation Increased 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 variation Whether good or bad, mutations are new to a population and increase diversity

7 Producing new kinds of organisms
Treat with radiation or chemicals to mutate Bacteria small and multiply quick/easy to pass along mutation Ex: bacteria that digest oil (used in oil spills) Plants Chemicals prevent chromosome separation in meiosis End 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 properties New technology: 1. extraction techniques 2. cut into smaller pieces 3. identify base sequences 4. make unlimited copies

10 1. Dna extraction Like in our strawberry lab!
Open up the cell and nucleus Separate DNA from everything else

11 2. Cutting dna… Restriction enzymes: enzyme that cuts DNA at a specific sequence of nucleotides Very specific Recombinant DNA: DNA produced by combining DNA from different sources Ex: human insulin gene and pig DNA- have pigs produce insulin

12 …and separating DNA Gel electrophoresis: procedure used to separate + analyze DNA fragments Place DNA (- charge) at one end of a gel and apply + charge to the other Fragments move across gel- smaller move faster/further Used 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 bases Sequencing: Start with unknown strand + DNA polymerase +nucleotide bases = complimentary strand is made Bases are dyed to identify them Now, everything is automated

14 4. Making copies Polymerase chain reaction (PCR): technology that allows scientists to make many copies of a gene How it works: Heat DNA- strands separate Cool and add primers- short pieces of DNA that tell DNA polymerase to start working Add free nucleotide bases + DNA polymerase Makes 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 DNA DNA MUST be integrated into a chromosome! Recombinant DNA!

16 Transforming bacteria
Plasmid: small circular DNA molecule Why plasmids? Replicate easily so foreign DNA will then be replicated Genetic marker: a gene that distinguishes bacteria with foreign DNA plasmid from ”regular” bacteria Antibiotics resistant genes used alot

17 Transforming plant cells
Use bacterium that inserts a plasmid with manipulated foreign DNA into plant cells Can also: Take up DNA when cell wall is removed Inject DNA directly into plant cells Either way, DNA MUST be integrated into the chromosome

18 Transforming animal cells
Cells are large enough for direct injection of DNA Enzymes used to cut and insert DNA into chromosome May also use genetic markers Gene 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 organisms Transgenic organism: an organism that contains genes from a different organism Gene from one inserted into the cell of another These transformed cells = a new organism!

21 Transgenic microorganisms
Insert human gene for proteins into bacteria Bacteria used to “harvest” human proteins Ex: insulin, growth factors, clotting factors

22 Transgenic plants Examples: Plants with natural insecticides
Plants that will resist weed-killing chemicals Rice with added vitamin A

23 Transgenic animals For research: mice with human immune systems
For food: Livestock with added growth hormone- grow faster/leaner Chicken that is resistant to food poisoning bacteria Milk that produces human proteins in it

24 cloning Clone: a member of a population of genetically identical cells produced from a single cell Single-celled bacteria= easy to clone Multicellular 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 cell Fused using an electric shock Cell will begin to divide- form an embryo Embryo is placed in foster mom’s uterus Development and birth happen as normally does

26 cloning

27 Cloning Pros and cons Pros Cons What else?
Ability to reproduce transgenic animals Ability to reproduce endangered species Cons Genetic defects Unknown side effects What else?

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