Biotechnology

Breeding The first biotechnology

Selective Breeding The breeding of organisms to produce certain desired traits in their offspring

Used to produce a new breed with a desired trait Only the ones with the desired trait are selected to reproduce Persian

Inbreeding Crossing organisms that have a similar genotype Used to maintain a desired set of traits Can result in problems and undesirable traits (p. 207) German Shepherd Sharpei

Outbreeding (hybridization) The crossing of distantly related organisms Usually involves two breeds of the same species Liger Mule

Genetic Engineering Any technique used to identify or change genes at the molecular level Involves the building of Recombinant DNA A molecule made from pieces of DNA from separate organisms

All genetic engineering experiments share 4 steps: Cleaving DNA – a desired gene is cut from DNA Producing Recombinant DNA – DNA fragment is put into the DNA of another cell

Cloning cells – growing a large number of genetically identical cells from a single cell Screening cells – cells that received the gene of interest are identified and isolated

Step 1: Cleaving DNA Enzymes called restriction enzymes are used to cut a DNA molecule into fragments

Restriction enzyme cuts out the desired gene from the DNA molecule at a specific nucleotide sequence

The incision is not at the center of the sequence but is staggered to one side The cut produces fragments with exposed nitrogen bases called “sticky ends”

DNA code GAATTC GAATTC CTTAAG G AATTC CTTAA G one end: G “sticky CTTAA end” other end: AATTC “sticky G end”

Sticky ends can pair with any other DNA fragment that has been cut with the same restriction enzyme

Step 2: Producing Recombinant DNA Restriction enzyme is used to cut open a plasmid

A plasmid is a small circular piece of DNA found in a bacterium that is separate from the bacterial chromosome The plasmid serves as a vector – a carrier of genetic material

Open plasmid and isolated gene are combined Sticky ends join and are sealed by the enzyme DNA ligase New combined DNA molecule is called Recombinant DNA

Step 3: Cloning Cells The recombinant plasmid is introduced into a bacterial cell Cells with the new plasmid reproduce making copies of the new gene This is called Gene Cloning

Step 4: Screening Cells The new bacterial cells are screened to see if they have the new gene The ones with the gene are isolated

Example: The gene for human insulin can be isolated and inserted into a plasmid Bacterial cells then produce human insulin

This is used by people who are diabetic Reduces the need for pig insulin which can cause allergic reactions

Identifying Sequences in DNA DNA Fingerprint DNA is cut into fragments by a restriction enzyme

Because of differences in nucleotide sequences, the number of cutting sites for a restriction enzyme varies among the DNA of different individuals producing fragments of different lengths The lengths are unique to each individual

Samples are separated by a process called Gel Electrophoresis a. DNA fragments are dropped into thin slits in a track of gel

The gel tracks have a (+) charge at one end and a (-) charge at the opposite end DNA has a (-) charge so the fragments move toward the (+) end of the gel

The smallest fragments move farthest along the tracks and the larger fragments stay toward the (+) end e. A unique banding pattern is produced f. Every person’s DNA has a unique pattern that can be used for identification

Gel electrophoresis can also be used to find the base-pair sequence of DNA Four different chemicals are used to recognize and cut four samples of the same DNA at each of the four bases (A, T, C, G)

The samples are then poured into four gel electrophoresis tracks Computers can read the order of the bases by analyzing the bands in the tracks

Human Genome Project The effort to identify the nitrogenous base sequence of all the DNA in every human chromosome Officially completed in April 2003

Gel electrophoresis can be used to determine if a person carries a genetic disorder The person’s pattern of DNA bands is compared with the pattern known to be associated with the disease If the two patterns match, that person may develop the disorder

Biotechnology and Medicine

Making genetically engineered drugs The human gene for insulin can be inserted into bacteria so the bacteria produce human insulin Human insulin is the first commercial product of genetic engineering

Other medically important proteins made using genetic engineering techniques: Anticoagulants – proteins involved in dissolving blood clots are used to treat heart attack patients

Genetically engineered Factor VIII is used to treat hemophilia patients This factor is free of viruses (HIV and Hepatitis B)

Making genetically engineered vaccines Bacteria are genetically engineered to act as antibodies and are safer than using a weakened form of a disease-causing virus

Curing Genetic Disorders Treatment involves changing the genes that cause a genetic disorder

Example: Cystic Fibrosis Secretion of excess mucus in the lungs caused by a malfunctioning gene This method has already had some success

Healthy genes that have recombined with certain viruses or carrier cells can be delivered to lung cells via a nasal spray The healthy genes can replace the malfunctioning genes, correcting the genetic defect

The New Agriculture

Making crops resistance to herbicides and insects The gene that is resistant to herbicides is inserted into plants The farmer treats the field with an herbicide and everything dies except the plants with the new gene Makes weed control easier

Making crops that need no fertilizer Genetically engineering crops to fix nitrogen Crops can be grown without adding fertilizer

Improving livestock production Growth hormone in the diet of dairy cows improves milk production The source of growth hormone has been extracting it from the brains of dead cows

The gene for growth hormone can now be inserted into bacteria so the bacteria produce the hormone This method is much less expensive and there is less chance of passing on disease (such as prion, ie. Mad Cow Disease) to the dairy cows

Bioinformatics

The use of computers to manipulate and analyze the growing quantities of genetic information available to the pharmaceutical, biomedicine and biotechnology industries