(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

Cell Transformation

Recombinant DNA

Host Cell DNA

Target gene

Modified Host Cell DNA

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

80% of processed foods in the U.S. are genetically modified

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

The Island

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

Gel Electrophoresis

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

(5/6) BR

1.Who are the parents of the soldier?

2. The murderer’s blood was found on the victim, and blood was found at 2 possible crime scenes. Where did the murder take place? And who did it????