Genetic Engineering

Genetic Engineering Process of replacing specific genes in an organism to ensure that the organism expresses a desired trait. Scientists take specific genes from one organism and put them in another.

How do you do it? Scientists need to know exactly where the particular gene for a desired trait is on a chromosome. A gene map shows the relative location of each known gene on a chromosome. Genome: all the genetic material in an organism. The Human Genome Project is useful for identifying wanted genes.

What does a gene map look like?

Types of Genetic Engineering Cloning Gene therapy Stem cells GMOs/transgenic organisms

Cloning An identical copy of a gene or an entire organism is produced. May be natural or engineered. Pros: organ transplants, saving endangered species Cons: genetic disorders and health problems

Gene Therapy Normal gene is inserted into an absent/abnormal gene. Once inserted, the normal gene begins to produce the correct protein or enzyme and eliminates the cause of a genetic disorder. Pros: curing previously incurable genetic disorders Cons: limited success because the host often rejects the injected genetic material

Stem Cells Stem cells are undifferentiated cells that have the potential to become specialized in structure or function. Stem cells are usually found in embryos, but some are in adults – these are harder to isolate. Pros: replace tissue that is deficient due to disease or damage. Cons: controversial methods of obtaining the cells

GMOs/transgenic organisms Genetically modified organism – genes are inserted or deleted; these genes usually come from different organisms. Used in biological and medical research, making medication and drugs, and agriculture. Pros: crops resistant to predators/herbicides, more food Cons: allergies, labeling issues, ethical concerns, environmental effects

Results of Genetic Engineering Better crops Plants can manufacture their own insecticides, they can have more protein, or they can spoil more slowly. Better animals for food Animals can be bigger, grow faster, or disease-resistant “Bacteria factories” Bacteria can be made to produce human hormones like insulin or growth hormone. Cure genetic disorders in humans In humans, it is theoretically possible to transplant copies of normal genes into the cells of people suffering from genetically carried diseases such a Tay-Sachs disease, cystic fibrosis, and sickle-cell anemia.

Selective Breeding The method of artificially selecting and breeding only organisms with a desired trait to produce offspring Almost all domesticated animals and most crop plants are the result of selective breeding

How does it work? In order for the parents to show strong expression for a trait, they must carry at least one gene for that trait. Once a breeder has successfully produced offspring with the desired set of characteristics, inbreeding continues. Inbreeding involves crossing individuals who are closely related, like siblings. Drawback: recessive gene defects often show up more frequently after several generations of inbreeding…like genetic diseases.

What are hybrids? Hybridization is a form of selective breeding. Involves choosing and breeding organisms that show strong expression for two different traits Purpose: produce an offspring that expresses both traits This occurs often between two different (but similar) species Offspring are often hardier (survive better) than either of the parents