Gene Technology

• Genomics - the study of entire genomes• Human genome project• Began in 1990• International effort to sequence the human genome. • 2.9 billion DNA base pairs in the human genome• Sequenced and mapped ~25,000 genes

Human Genome Project

• Findings:– Suprisingly few genes for the large human

genome– Most DNA is non-coding – does not code for a

protein– Many genes found in humans are the same as in

other species– All humans are almost genetically identical

Manipulating genes

• Genetic engineering – moving genes from one organism into another

• DNA extracted out of cells using a simple chemical process. Cells are opened and then DNA is separated from the rest of the cell parts.

Gene manipulation

• Specific sequences of DNA can be excised out of the genome of organisms. – Ex. Gene for human insulin

• Restriction enzymes - enzymes that cleave DNA at specific sequences of nucleotides.– Cuts it down into more manageable pieces

Restriction enzymes

• Sticky ends - overhang created by some restriction enzymes cutting in an offset manner.

• Blunt ends - cleavage that leaves DNA cut straight across.

Recombinant DNA

• Cloning vector - a carrier that is used to clone a gene and transfer it from one organism to another.

• Plasmid – ring of DNA found in bacterium in addition to its main chromosome.

Recombinant DNA

• Donor gene - a specific gene isolated from an organism– Ex. Insulin gene needed to produce insulin for

diabetes patients• Recombinant DNA - the combination of DNA from

two or more organisms. • The donor gene can be placed into an organism to

give it a new characteristic. • Organisms with recombinant genes may be called

transgenic, recombinant, or genetically modified.

Genetically Modified or Transgenic Organisms

• Genetic engineering is used to create GMOs used in agriculture, medicine, industry, and basic research.

• Bioremediation – using microbes for environmental cleanup.

• First GMO was a genetically engineered bacterium that can digest oil.

Food Crops

• Bacillus thuringiensis (Bt) gene that produces insecticide is inserted to many crops.

• Transgenic rice with added vitamin A reduced vision impairment in Asian countries.

• Crops can also be modified to make them easier to grow and to increase nutrition values.

Livestock

• Livestock engineered to grow faster, more muscle, less fat, and even more milk with specific proteins in it.

• Some GMOs are sold as unique pets

Medicinal uses

• Gene for insulin is spliced into cloning vector and inserted into a bacterium to produce needed protein for diabetes patients.

• Hemophilia patients also are treated with proteins produced this way.

MRSA

• Due to the excessive use of antibiotics a new bacteria that is resistant to multiple antibiotics has grown rampant.

• MRSA is a type of Staphylcoccus aureus that has developed resistance to penicillin and methicillin, the two drugs normally used to treat staph infections.

Gene therapy

• Copies of normal gene are cloned by bacteria and then inserted into viruses or transport vesicles.

• Limited success because human body has many protections against the invasion and genetic change that viruses cause.

• Used to treat cystic fibrosis today. These patients have a defective gene for an enzyme in secretory cells.

•Gene therapy – replacing an absent or faulty gene with a working one.

Stem cells

• Unspecialized cells that have the potential to differentiate.

• Bone marrow cells give rise to various blood cells.

Stem Cells

• Cells in new embryos are able to develop into any type of cell except germ cells.

• They can be grown in tissue cultures.

• Tissues can be re-implanted into a patient whose tissues are damaged.

Cloning

• Clone – member of a population of genetically identical cells produced from a single cell. – Ex. Asexual reproduction in bacteria, budding in plants

and fungi, and self-fertilization of plants and animals • Very few large animals can clone themselves. • In 1997, Scottish scientist Ian Wilmut announced he had

cloned the first mammal, a sheep named “Dolly”.

Ethical and Social Issues

What do you think about stem cell

research, genetically modified

organisms, and cloning? Should it be allowed? Do the benefits out way the risks?

More DNA Technologies

• Gel electrophoresis – electric current used to separate fragments of DNA.

• DNA fingerprint – pattern of bands created by fragments from an individual’s DNA. – Used in Forensics to indicate who was at the scene

of a crime.

DNA Fingerprints

Which of the suspects committed the crime?

A. Suspect 1

B. Suspect 2

C. The boyfriend

D. None of the above

Polymerase Chain Reaction (PCR)

• PCR – process that replicates DNA sequences

• Place host DNA, primers, polymerase, and nucleotides in a test tube and control temperature to start and repeat process over and over again.

Other DNA Technologies

• Probe – short DNA or RNA strand with attached radioactive or fluorescent materials to “tag” specific sequences. – Nucleotide sequences are complementary to the

gene of interest• Southern blot – used to indicate certain fragments that

hybridized with a probe.

DNA Sequencing

• The process of determining the exact order of every nucleotide in a gene.