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Genetic Engineering. Biology Mrs. Appel Pgs 247-259. Breeding Strategies. Farmers and ranchers throughout history have tried to improve plants and animals by selecting the most desired organisms to breed. Selective Breeding : Mating individuals with a desired trait. Ex: milk cows

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Genetic Engineering

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Genetic Engineering

Biology

Mrs. Appel

Pgs 247-259


Breeding Strategies

Farmers and ranchers throughout history have tried to improve plants and animals by selecting the most desired organisms to breed.

  • Selective Breeding: Mating individuals with a desired trait. Ex: milk cows

  • Inbreeding: Mating individuals with similar characteristics. Ex: pure-bred dogs, royal families.

    • Risks: increased chance of recessive genetic defects in offspring.


Breeding Strategies

  • Hybridization: Mating 2 dissimilar individuals. Ex: mules

    • Often involves mating individuals from 2 different species

    • Hybrid vigor: offspring are hardier than parents


Mutations

  • Mutation: Change in the DNA code.

  • Breeders may use mutagens to increase the chance of mutations, with luck a few mutants may have desirable mutations.

    • Bacteria:


Genetic Engineering

  • What is genetic engineering?

    -the process of isolating a desired gene from the DNA of one organism and transferring it to the DNA of another organism.


Genetic Engineering

  • What are some applications of genetic engineering?

    -Medicines, vaccines, gene therapy, agriculture,


Genetic Engineering

  • How does genetic engineering work?

    -Genetic engineering experiments use different approaches , but most share 4 or 5 basic steps……….


Step 1- Cutting DNA

  • DNA is cut with restriction enzymes to isolate a particular gene. The RE recognize and cut the DNA at a specific sequence callled a recognition site.

  • This creates “sticky ends” or “blunt ends” on the gene

  • pg 251, Figure 12-6


Step 2- Making the Recombinant DNA

  • The particular gene that has been cut out is inserted into plasmid DNA. This is called the “gene of interest”.

(Gene of interest)


What is a plasmid??


Step 2- Making the Recombinant DNA

(Gene of interest)

  • Vectors are used to carry gene of interest to another cell. Some examples of vectors are: viruses, yeast and plasmids.

  • DNA Ligase is added to help bond the DNA together.

  • Recombinant DNA has DNA from 2 different species or cells.

  • Pg 253, Fig. 12-8


Step 3- Inserting the DNA into a Cell

  • Recombinant DNA is then put

    back into bacterial cells by:

    • Salt solution via osmosis

    • Microinjection with glass

    • needles.

    • DNA fused to wire pellets

    • and shot at DNA with a

    • microscopic gun.

    • Video on Gene Transfer


Step 4- Gene Cloning

  • In a process called gene cloning, many copies of the gene of interest are made each time the host cell divides.

    • Bacteria cells: accomplished by a process called binary fission


Cloning- (made easy)


Cloned Animals-

Makes it possible to produce large numbers of identical organisms with favorable genetic characteristics.

Hundreds of cloned animals exist today, but the number of different species is limited. Attempts at cloning certain species such as monkeys, chickens, horses, and dogs, have been unsuccessful.


  • Celebrity Sheep Has Died at Age 6

  • Dolly, the first mammal to be cloned from adult DNA, was put down by lethal injection Feb. 14, 2003. Prior to her death, Dolly had been suffering from lung cancer and crippling arthritis. Although most Finn Dorset sheep live to be 11 to 12 years of age, postmortem examination of Dolly seemed to indicate that, other than her cancer and arthritis, she appeared to be quite normal. The unnamed sheep from which Dolly was cloned had died several years prior to her creation. Dolly was a mother to six lambs, bred the old-fashioned way.


Can organs be cloned for use in transplants?

  • Scientists hope that one day cloning can be used to generate tissues and organs for transplants. To do this, DNA would be extracted from the person in need of a transplant and inserted into an enucleated egg. After the egg containing the patient's DNA starts to divide, embryonic stem cells that can be transformed into any type of tissue would be harvested. The stem cells would be used to generate an organ or tissue that is a genetic match to the recipient. In theory, the cloned organ could then be transplanted into the patient without the risk of tissue rejection. If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced.


Step 5- Screening

  • Cells that have received the particular gene of interest are distinguished from the cells that did not take up the vector with the gene of interest.

  • Examples: glowing cells, antibiotic resistant bacteria


Step 5- Screening


Gene splicing-overview


Insertion- microinjection


Insertion- microinjection


Insertion and screening


Transgenic Organisms

  • Transgenic: have foreign DNA

    • Transgenic Bacteria: ex:insulin, growth hormone, interferon and blood clotting factor.


Transgenic Plants: ex: insecticides, fertilizer, resistance to harsh environmental conditions and viruses, glowing plants??


Transgenic Animals: ex: growth hormone gene inserted in cattle and fish, farm animals resistant to certain diseases.

Would it be


Some transgenic info.

  • In 2003, about 167 million acres grown by 7 million farmers in 18 countries were planted with transgenic crops, the principal ones being herbicide- and insecticide-resistant soybeans, corn, cotton, and canola. Other crops grown commercially or field-tested are a sweet potato resistant to a virus that could decimate most of the African harvest, rice with increased iron and vitamins that may alleviate chronic malnutrition in Asian countries, and a variety of plants able to survive weather extremes.

  • On the horizon are bananas that produce human vaccines against infectious diseases such as hepatitis B; fish that mature more quickly; fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties.


Genetically Modified (transgenic) Products

  • Benefits

  • Crops

    • Enhanced taste and quality

    • Reduced maturation time

    • Increased nutrients, yields, and stress tolerance

    • Improved resistance to disease, pests, and herbicides

    • New products and growing techniques

  • Animals

    • Increased resistance, productivity, hardiness, and feed efficiency

    • Better yields of meat, eggs, and milk

    • Improved animal health and diagnostic methods

  • Environment

    • "Friendly" bioherbicides and bioinsecticides

    • Conservation of soil, water, and energy

    • Bioprocessing for forestry products

    • Better natural waste management

    • More efficient processing

  • Society

    • Increased food security for growing populations


GM products

  • Controversies

  • Safety

    • Potential human health impact: allergens, transfer of antibiotic resistance markers, unknown effects Potential environmental impact: unintended transfer of transgenes through cross-pollination, unknown effects on other organisms (e.g., soil microbes), and loss of flora and fauna biodiversity

  • Access and Intellectual Property

    • Domination of world food production by a few companies

    • Increasing dependence on Industralized nations by developing countries

  • Ethics

    • Violation of natural organisms' intrinsic values

    • Tampering with nature by mixing genes among species

    • Objections to consuming animal genes in plants and vice versa

    • Stress for animal

  • Labeling

    • Not mandatory in some countries (e.g., United States)

    • Mixing GM crops with non-GM confounds labeling attempts

  • Society

    • New advances may be skewed to interests of rich countries


DNA Sequencing

Human Genome Project

A map of a portion of a human chromsome


DNA Sequencing

  • Sequencing is figuring out the code of specific genes. After time, finding out code for an entire organism.

    • Many copies of DNA needed (cloning)

    • Radioactive Label

    • Gel Electrophoresis, Fig.12-9

      Video on Genetic Engineering Applications


DNA Fingerprinting

•1985- Alec Jeffreys introduced DNA fingerprinting. It is based on the fact that no two people (except identical twins), have the same DNA fingerprint.

•Uses: criminal investigations, paternity, rape cases, etc.

•Very small amounts of DNA are needed, taken from blood, saliva,hair, urine, etc.


DNA Fingerprinting

Making A DNA fingerprint

DNA is cut by restriction enzymes at specific recognition sites.

DNA is micro-pipetted into the wells.

An electric current moves the DNA across the gel.

-DNA has a neg. charge and will travel towards the pos. end of the gel

-small fragments of DNA will travel further.

4. The DNA bands are compared.


DNA

Fingerprinting


Gel Electrophoresis


DNA

Fingerprinting


PCR- polymerase chain reaction


Gene Therapy


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