GENETIC ENGINEERING Chapter 13 Selective Breeding n Humans
GENETIC ENGINEERING Chapter 13
Selective Breeding n Humans use selective breeding to pass desired traits on to the next generation of organisms. n Allows only those animals with desired characteristics to produce the next generation. n 2 Types of Selective breeding: 1. 2. Hybridization Inbreeding
Hybridization n Hybridization – cross breeding non-similar individuals that bring together the best traits of both organisms. q Produces hybrids (mixed organisms) that are often BETTER than either parent… n n disease resistant plants with higher food producing capacity
Inbreeding n Inbreeding - continued breeding of individuals with similar characteristics q Used to maintain the desired characteristic of an organism. n q Ex Dog breeding (beagles, poodles, golden retrievers, etc. ) Risks of inbreeding: n genetically similar breeds increase the likelihood of passing on recessive alleles for genetic defects
Increasing Variation n Breeders can increase the genetic variation in a population by causing mutations, which are the ultimate source of genetic variability. q mutations are inheritable changes in DNA that occur spontaneously n n radiation or chemicals may be used If lucky, breeders can produce a few mutants with desirable characteristics that are not found in the original population
Manipulating/ Changing DNA n Genetic engineering is used to make changes in the DNA. q q q First, the DNA is extracted/ removed from an opened cell. Restriction enzymes are then used to cut the DNA at a specific section of nucleotides. The fragments are then separated analyzed using gel electrophoresis (used to compare genomes of different organisms) this way scientists can locate & identify single genes out of millions in a genome.
Cutting DNA with Restriction Enzymes
Separating DNA with Gel Electrophoresis
DNA Sequencing n In DNA sequencing, a complementary DNA strand is made using a small proportion of fluorescently labeled nucleotides.
Cutting, Pasting, & Making Copies of DNA n Recombinant DNA is produced by combining DNA from different sources. q n These DNA sequences are joined by using enzymes to splice/ squeeze the DNA together A polymerase chain reaction (PCR) allows biologists to make many copies of a particular gen q A few dozen cycles of PCR can produce millions of copies of a DNA sequence
During Cell Transformation, a cell incorporates/ includes foreign DNA into its own DNA. A plasmid (circular DNA) is made, and contains a genetic marker, which distinguishes the human DNA from the bacterial DNA. One way to make recombinant DNA is to insert a human gene into bacterial DNA. The new combination of genes is then returned to a bacterial cell, and the bacteria can produce the human protein.
Knock-Out Genes n Recombinant DNA can replace a gene in an animal’s genome. When recombinant DNA is inserted into the target location, the host cell’s original gene is lost or “knocked out” of its place.
Applications of Genetic n Engineering Transgenic Organisms: organisms that contain some genes from other organisms
Transgenic Organisms are the basis for Biotechnology!!! q q q Transgenic bacteria now produce a host of important substances useful for health & industry. n Human insulin, growth hormone, and clotting factor are now produced by transgenic bacteria. Transgenic animals have been used to study genes and improve the food supply. n These animals often grow faster and produce LESS fatty meat. Transgenic plants are an important part of our food supply. n Many transgenic plants produce a natural insecticide, so the crops do not have to be sprayed with pesticides.
Cloning – a member of a population of genetically identical cells produced from a single cell.
Cloning…Meet Dolly the Sheep!!!
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