S ELECTIVE B REEDING Selective breeding – (artificial selection) Breeders select individuals with desirable traits to breed. Offspring inherit desirable traits from parents (hopefully).
S ELECTIVE B REEDING Luther Burbank used selective breeding to develop Shasta daisies, a popular variety.
S ELECTIVE B REEDING Hybridization Crossing dissimilar individuals to produce offspring with “hybrid vigor”.
H YBRIDIZATION A mule is a cross between a horse and a donkey.
S ELECTIVE B REEDING Inbreeding Crossing similar individuals to maintain desired traits.
I NBREEDING Inbreeding maintains the desirable traits of Labradors, but may make the breed more susceptible to disease and physical abnormalities.
which crosses consists of Selective Breeding for example Inbreeding Hybridizatio n Similar organisms Dissimilar organisms for example Organism breed A Organism breed B Retains desired characteristics Combines desired characteristics whic h which crosses whic h Section 13-1 Concept Map
I NCREASING V ARIATION Inducing mutations increases variation in a population. Variation in a population is a good thing. Radiation and chemicals are used.
I NDUCING M UTATIONS Bacteria have been induced to digest oil.
I NDUCED MUTATIONS Strawberries have been induced to be polyploid making bigger, sweeter strawberries.
C ELL T RANSFORMATION When a bacterial cell takes in DNA from outside the cell, the external DNA gets incorporated into the bacterium’s own DNA. Recombinant DNA has been made. The cell has been transformed. It will make a new protein(s).
T RANSFORMING BACTERIA Bacterial plasmids (circular DNA) are used to produce human hormones (HGH, insulin, clotting factor). Plasmids are useful because they are readily taken in by bacteria and they easily replicate within a cell. Also genetic markers in the plasmid help isolate transformed cells from non-transformed cells. Typically the gene for resistance to antibiotics is used as a genetic marker. After transformation, the culture is treated with an antibiotic to kill all non-transformed cells.
Human Cell Gene for human growth hormone Recombinant DNA Gene for human growth hormone Sticky ends DNA recombination DNA insertion Bacterial Cell Plasmid Bacterial chromosome Bacterial cell for containing gene for human growth hormone Section 13-3 Figure 13-9 Making Recombinant DNA
T RANSFORMING PLANT CELLS Plant cells don’t readily take in external DNA. Plant cells are grown in culture with their cells walls removed. Then plasmids are directly injected into the cells or carried into the cells with a bacterium.
Recombinant plasmid Gene to be transferred Agrobacteriu m tumefaciens Cellular DNA Transformed bacteria introduce plasmids into plant cells Plant cell colonies Complete plant is generated from transformed cell Inside plant cell, Agrobacterium inserts part of its DNA into host cell chromosome Section 13-3 Figure 13-10 Plant Cell Transformation
T RANSFORMING ANIMAL CELLS DNA is injected directly into egg cells. DNA can be carried into cells with viruses. Once inside the nucleus, recombinant DNA can replace a host cell gene making it possible to treat disorders caused by single genes. This therapy is called “gene replacement”. Ex: cystic fibrosis
Recombinant DNA Flanking sequences match host Host Cell DNA Target gene Recombinant DNA replaces target gene Modified Host Cell DNA Section 13-3 Knockout Genes
T RANSGENIC O RGANISMS Transgenic organisms contain genes from different species. Transgenic bacteria produce human proteins. Transgenic animals grow faster and produce leaner meat. Transgenic plants are more resistant to disease. Foods obtained from transgenic organisms are labeled “genetically modified”.
C LONING A clone is a member of a genetically identical population. In 1997 the first mammal was cloned, a sheep named Dolly.
A donor cell is taken from a sheep’s udder. Donor Nucleus These two cells are fused using an electric shock. Fused Cell The fused cell begins dividing normally. Embryo The embryo is placed in the uterus of a foster mother. Foster Mother The embryo develops normally into a lamb—Dolly Cloned Lamb Egg Cell An egg cell is taken from an adult female sheep. The nucleus of the egg cell is removed. Section 13-4 Figure 13-13 Cloning of the First Mammal