(5/4) bellringer: biotechnology 1. what do you know about the following topics? stem cell research...
TRANSCRIPT
(5/4) Bellringer: Biotechnology
1. What do you know about the following topics? Stem cell research Genetically modified
organisms (GMOs) Gene therapy Cloning
2. Do you think humans have gone too far in terms of “Playing God?” Explain!
Gene Therapy A technique for correcting defective genes that cause genetic
disorders (what are some examples of genetic disorders?) A vector is used to deliver the therapeutic gene to the patient.
Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Small bacterial chromosomes called plasmids are also used.
The genetic code is UNIVERSAL!
Target cells that express the mutation are “infected” with the viral vector. The vector then injects its genetic material (DNA or RNA) containing the therapeutic human gene into the target cell
The viral DNA then becomes a part of the cell’s genome, replacing the mutated gene, and the cells express the gene
Restriction enzymes like EcoRI cut DNA into fragments
Fragments from different DNA cut by the same restriction enzymes can form recombinant DNA
Gene TherapyPros
Treatment of a genetic disease for which there is no treatment
Potential for life-long treatment from a single injection (a cure)
Cons Autoimmune response Viruses may target the wrong
cells May be inserted into the wrong
location in the DNA May lead to the development
of a tumor
(5/5) Bellringer
1. What is a DNA fingerprint? If you don’t know, take a guess.
2. Some mafia gangster robbed a bank, and then inexplicably left blood and semen everywhere for CSI to analyze. Based on this DNA fingerprint, who dunnit?
Transgenic Plants/Animals (GMOs: Genetically Modified Organisms)
Introducing new traits into organisms using recombinant DNA technology
Bacterial transformation using restriction enzymes and plasmids
Recombinant DNA
Gene for human growth hormone
Gene for human growth hormone
Human Cell
Bacteria cell
Bacterial chromosome
Plasmid
Sticky ends
DNA recombination
Bacteria cell containing gene for human growth hormone
DNA insertion
Transgenic Plants/Animals (GMOs: Genetically Modified Organisms)
There are several methods for introducing genes into plants and animals: infecting plant cells with viruses or plasmids as vectors
carrying the desired gene (like in gene therapy) “Gene guns” can “shoot” the host cells with particles of
DNA. Cells may be treated with chemicals to make plasma
membranes more permeable—DNA diffuses in. Electroporation—a short electric shock creates temporary
pores in membranes, and DNA can enter.
Transgenic Plants
Complete plant generated from transformed cell.
Inside plant cell, Agrobacterium inserts part of its DNA into host cell chromosome.
Plant cell colonies
Transformed bacteria introduce plasmids into plant cells.
Agrobacterium tumefaciens
Cellular DNA
Gene to be transferred
Recombinant plasmid
Transgenic Plants (GMOs)Pros
Improved Nutritional Quality (Ex: adding vitamin A to rice)
Eliminate pesticide use Biopharmaceuticals: the genes for
proteins to be used in human (and animal) medicine can be inserted into plants and expressed by them
Greater yields
Cons Endangering native species Unknown health risks “Genetically contaminate"
wild populations, non-GMO farms, and ecosystems
Environmental pollution from overuse of herbicides
Evolution of stronger, more resistant species (e.g., weeds, pests)
Insect Resistance Herbicide Resistance
Pharming: production of pharmaceuticals in farm animals or plants
Ex: Transgenes are inserted into fertilized eggs of sheep next to the promoter for lactoglobulin—a protein in milk.
Transgenic animals are raised that produce large quantities of the desired protein (e.g., human growth hormone) in their milk
Human protein is extracted from the milk to be administered to patients
Fertilized eggs containing the transgene are implanted into females who give birth to transgenic offspring
Transgenic animals: Taiwan breeds fluorescent green pig
The transgenic pigs, commonly used to study human diseases, would help researchers monitor and trace changes of the tissues during the physical development
“FOR THE FIRST TIME, RESEARCHERS EDIT THE GENES OF HUMAN EMBRYOS”Rumors that this research was underway turn out to be true
Cloning
Making an exact copy of an organism by using its DNA
Somatic Cell Nuclear Transfer: a nucleus containing DNA is inserted into an “empty” (enucleated) egg cell. Then the embryo is implanted in a surrogate who will carry the fetus to term and deliver a new offspring (clone)
Cloning
Donor Nucleus from udder cell
Fused cell
Embryo
Egg Cell
Foster MotherCloned Lamb
Nucleus removed
Electric shock fuses cells
CloningPros
organ transplant propagation of animals facing
extinction produce skin, cartilages, and
bones to save the victims of burns and accidents
produce cells to cure cancer, or repair the retina, or the spinal column
Cons ETHICS Has not been perfected yet Health risks from mutation
of genes Animal clones have had:
shorter life expectancy liver failure compromised immune
function tumor growth
Stem Cell Research Stem cells have the potential to differentiate into any type of
specialized cell in the body Totipotent stem cells can form an entire organism Pluripotent stem cells can form any type of cell but not an entire
organism Induced pluripotent stem cells result from dedifferentiating cells
Cultured iPS cells have been used for cell therapy in animals Research aims to heal injuries and disorders in which cells are lost and
cannot be replaced (Skin Gun) Somatic cell nuclear transfer can be used to culture stem cells
Stem Cell Research
Pros Can be used to treat
diseases which currently have no cure
replacement cells and tissues/organs
Cons Come from human
embryos with the potential to grow and develop
ETHICS
DNA Fingerprinting Everyone has a unique DNA “fingerprint” (nucleotide sequence) A person’s DNA is the same in every cell Procedure:
DNA is extracted from cells and mixed with restriction enzymes which cut the DNA at specific sequences
Gel electrophoresis: DNA fragments are exposed to electrical current and separate leaving a unique pattern…a DNA “fingerprint”
DNA is negatively charged so it moves towards the + end Short fragments of DNA move faster and farther Fragment patterns can be compared from DNA samples taken from
different individuals
DNA Fingerprinting
Pros DNA is unique from person to
person but the same from cell to cell in one person
Paternity and Maternity Criminal Identification and
Forensics Personal Identification Wildlife Management
Cons Invasion of privacy
(ETHICS) Genetic disorders could
affect life and health insurance premiums
Do you want to know if you have a genetic disorder that will strike in middle age?
DNA fingerprinting = CSI
Smaller fragments move faster/farther
Thicker bands contain more copies of that fragment