GENETIC ENGINEERING Chapter 11

Basic Steps of Genetic Engineering ◦ genetic engineering manipulating genes for practical purposes Example: ◦ recombinant DNA —DNA made from two or more different organisms.

Manipulating DNA Restriction enzymes recognize and bind to specific short sequences of DNA cut the DNA between specific nucleotides vector : carries a gene of interest into another cell. Commonly used vectors include: Viruses Yeast plasmids

Cutting DNA and Making Recombinant DNA ◦ Restriction enzymes recognize a specific sequence of DNA. ◦ short single strands on each end that are complementary to each other called sticky ends. ◦ bond together by means of complementary base pairing

Restriction Enzymes Cut DNA

4 Basic Steps of Genetic Engineering Step 1 DNA is cut by restriction enzymes Step 2 Recombinant DNA is produced. Step 3 gene cloning, many copies of the gene of interest are made each time the host cell reproduces. Step 4 Cells undergo selection and then are screened.

In order to visualize or isolate genese: DNA cut into fragments by restriction enzymes. DNA fragments are separated by gel electrophoresis, a technique that uses an electric field within a gel to separate molecules by their size.

The Human Genome Project ◦ 1990: a quest to sequence all 3 billion letters, or base pairs, in the human genome ◦ data generated freely and rapidly available on the Internet, ◦ accelerate the pace of medical discovery ◦ spurred a revolution in biotechnology innovation. ◦ April 2003, researchers successfully completed the Human Genome Project, under budget and more than two years ahead of schedule.

Human Genome Project Today ◦ fueled the discovery of more than 1,800 disease genes. ◦ find a gene suspected of causing an inherited disease in a matter of days, rather than the years it took before the genome sequence was in hand. ◦ more than 2,000 genetic tests for human conditions ◦ At least 350 biotechnology-based products resulting from the Human Genome Project are currently in clinical trials. ◦ Having the complete sequence of the human genome is similar to having all the pages of a manual needed to make the human body. The challenge now is to determine how to read the contents of these pages and understand how all of these many, complex parts work together in human health and disease.

The Geography of the Genome ◦ Only 1 to 1.5 percent of the human genome is DNA that codes for proteins. ◦ Each human cell contains about six feet of DNA, but less than 1 inch of that is devoted to exons. ◦ Exons are scattered about the human genome in clumps that are not spread evenly among chromosomes. o Human cells contain only about 30,000 to 40,000 genes. o This is only about double the number of genes in a fruit fly.

Genetically Engineered Drugs and Vaccines ◦ genetic disorders and other human illnesses occur when the body fails to make critical proteins ◦ pharmaceutical companies produce medically important proteins in bacteria using genetic engineering techniques. ◦ Example: Factor VIII, a protein that promotes blood clotting, is an example of a GM medicine (genetically modified; a drug manufactured by genetic engineering).

Genetically Engineered Medicines

Vaccines ◦ solution containing all or part of a harmless version of a pathogen (disease-causing microorganism). ◦ immune system recognizes the pathogen’s surface proteins and responds by making defensive proteins called antibodies. ◦ if the same pathogen enters the body, the antibodies are there to combat the pathogen and stop its growth before it can cause disease.  Traditionally prepared either by killing a specific pathogenic microbe or by making the microbe unable to grow.  small but real danger that a failure in the process to kill or weaken a pathogen will result in the transmission of the disease to the very patients seeking protection  Vaccines made by genetic engineering techniques avoid the dangers of a traditional vaccine.

Genetically Engineered Vaccines

DNA Fingerprinting ◦ no two individuals have the same genetic material (except for …………….) ◦ DNA fingerprint : pattern of dark bands on photographic film made when an individual’s DNA restriction fragments are separated by gel electrophoresis ◦ DNA fingerprinting is useful in forensics; can be performed on a sample of DNA found in blood, semen, bone, or hair

Improving Crops ◦ genetic breeding selecting seeds from their best plants, replanting them, and gradually improving the quality of successive generations. ◦ genetic engineers add favorable characteristics to a plant by manipulating the plant’s genes. ◦ example, crops that are resistant to insects by inserting a certain gene isolated from soil bacteria into crop plants. Genetic engineers have been able, in many instances, to improve the nutritional value of crops

Genetic Engineering and Cotton Plants Section 3 Genetic Engineering in Agriculture Chapter 11

Risks of Genetically Modified Crops Potential Problems ◦ Some scientists are concerned that the use of GM crops and the subsequent use of glyphosate will eventually lead to glyphosate- resistant weeds. ◦ Some GM crops have genes added to improve nutritional character, as was done in rice. It is important to check that consumers are not allergic to the product of the introduced gene.

Are GM Crops Harmful to the Environment? ◦ it may be possible that introduced genes pass from GM crops to their wild or weedy relatives. ◦ Pests are not likely to become resistant to GM toxins as quickly as they now become resistant to the chemical pesticides that are sprayed on crops. ◦ Scientists, the public, and regulatory agencies must work together to evaluate the risks and benefits of GM products.

Gene Technology in Animal Farming ◦ traditional breeding and selection programs. ◦ genetic-engineering techniques to improve or modify farm animals. ◦ Example:add GM growth hormone to the diet of cows to increase milk production.

Making Medically Useful Proteins ◦ addition of human genes to the genes of farm animals in order to get the farm animals to produce human proteins in their milk. ◦ animals are called transgenic animals because they have foreign DNA in their cells. ◦ cloning animals is a way of creating herds of identical animals that can make medically useful proteins.

Problems with Cloning The Importance of Genomic Imprinting ◦ Technical problems in reproductive cloning lie within a developmental process that conditions eggs and sperm so that the right combination of genes are turned “on” or “off” during early development. ◦ The process of conditioning the DNA during an early stage of development is called genomic imprinting. ◦ genomic imprinting, chemical changes made to DNA prevent a gene’s expression without altering its sequence.