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Lecture 12

BSC 108 Lecture 12: Biology Chapter 12 Notes

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Biological Sciences
BSC 108
Christina Yates

Biology Chapter 12 Notes Recombinant DNA Technology • A set of techniques for combining genes from different sources into a single DNA molecule ➢ An organism that carries recombinant DNA is called a genetically modified (GM) organism (GM0) • Recombinant DNA technology is applied in the field of biotechnology ➢ Biotechnology uses various organisms to perform practical tasks Recombinant DNA Techniques • Bacteria are the workhorses of modern biotechnology • To work with genes in the lab, biologists often use bacterial plasmids • Plasmids are small, circular DNA molecules that are separate from the much larger bacterial chromosome • Plasmids can easily incorporate foreign DNA • Plasmids are readily taken up by bacterial cells • Plasmids then act as DNA carriers that move genes from one cell to another Genetically Engineered Products • By transferring the gene for a desired protein product into a bacterium, proteins can be produced in large quantities • In 1982, the world’s first genetically engineered pharmaceutical product was produced • Humulin, human insulin, was produced by genetically modified bacteria by Eli Lily • Prior to the development of Humulin, diabetes was treated using insulin from cows and pigs • These types of insulin can cause adverse reaction in recipients • Humulin was the first product of this type approved by the FDA DNA Technology • DNA technology is also helping medical researchers develop vaccines • A vaccine is a harmless variant or derivative of a pathogen • Vaccines are used to prevent infectious diseases Genetically Modified (GM) Foods • Today, DNA technology is quickly replacing traditional plant-breeding programs • Today roughly half of the American crops of soybeans and corn are genetically modified in some way • Corn has been genetically modified to resist insect infestation ➢ This corn has been damaged by the European corn borer • Rice has been genetically modified to contain beta-carotene, provide vaccines against cholera, and grow in salt water. ➢ Golden rice – our bodies use beta-carotene to make vitamin A Farm Animals and “Pharm” Animals • While transgenic plants are used today as commercial products, transgenic whole animals are currently only in the testing phase. • Transgenic sheep may carry a gene for a human blood protein to help in the treatment of cystic fibrosis • While transgenic animals are currently used to produce potentially useful proteins, none are yet found in our food supply. • It is possible that DNA technology will eventually replace traditional animal breeding Human Gene Therapy • Human gene therapy seeks to treat disease by altering the genes of the afflicted person ➢ A recombinant DNA procedure ➢ The mutant version of a gene is replaced or supplemented with a properly functioning one ➢ Viruses are used to deliver the gene Treating Severe Combined Immunodeficiency • SCID is a fatal inherited disease caused by a single defective gene ➢ The gene prevents the development of the immune system • David Vetter “Bubble boy” • Since 2000, gene therapy has successfully cured 22 children with inborn SCID • Unfortunately, three of the children developed leukemia and one of them died DNA, Guilt, and Innocence • DNA profiling is the analysis of DNA samples that can be used to determine whether the samples come from the same individual • DNA profiling can therefore be used in courts to indicate if someone is: ➢ Guilty ➢ Innocent Crime Scene Investigations: Murders in a Small Town • On November 22, 1983, ➢ A 15 year old girl was raped and murdered on a quiet country lane ➢ Three years later, another 15 year old girl was raped and murdered • DNA fingerprinting of DNA samples from suspects and the crime scene ➢ Proved one man guilty and another man innocent DNA Profiling and Forensic Science • DNA technology has rapidly revolutionized the field of forensics ➢ Forensics is the scientific analysis of evidence from crime scenes • DNA fingerprinting can be used to determine whether or not two samples of genetic material are from a particular individual Murder, Paternity, and Ancient DNA • DNA fingerprinting ➢ Has become a standard criminology tool ➢ Has been used to identify victims of the World Trade Center attack and Hurricane Katrina ➢ Can be used in paternity cases • DNA fingerprinting is also used in evolutionary research ➢ To study ancient of DNA, such as that of Cheddar Man ➢ A direct ancestor of a local schoolteacher DNA Profiling Techniques • The polymerase chain reaction (PCR) is a technique by which any segment of DNA can be copied quickly and precisely ➢ Through PCR, scientists can obtain enough DNA from even minute amounts of blood or other tissue to allow DNA fingerprinting Gel Electrophoresis • Gel Electrophoresis ➢ Can be used to separate the DNA fragments obtained from different sources • The DNA fragments are visualized as “bands” on the gel ➢ The bands of different DNA samples can then be compared Safety and Ethical Issues • As soon as scientists realized the power of DNA technology, they began to worry about potential dangers such as: ➢ The creation of hazardous new pathogens ➢ The transfer of cancer genes into infectious bacteria and viruses • Strict laboratory safety procedures have been designed to protect researchers from infection by engineered microbes ➢ Procedures have also been designed to prevent microbes from accidentally leaving the laboratory The Controversy Over GM Foods • GM strains account for a significant percentage of several agricultural crops in the United States • Advocates of a cautious approach have some concerns: ➢ Crops carrying genes from other species might harm the environment ➢ GM foods could be hazardous to human
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