Biotechnology and Society Chapter 14
Biotechnology • Biotechnology • The use of recombinant DNA technology to produce commercial goods and services • Chp13 discussed how DNA from different organisms could be combined to create specific DNA molecules with the ability to grow in various types of cells. (1970’s) • Now, recombinant DNA technology is making a direct impact on our everyday lives. • This has generated unresolved ethical issues.
Biotechnology • …in this chapter • Pharmaceutical products made in transgenic plants and animals • Use of stem cells to treat disease • GMOs • Use of animals that model human diseases • Use of DNA in forensics and other fields
14.1 Biopharming: Making Human Proteins in bacteria, cells, and animals • Before biotechnology insulin, growth hormone, blood-clotting factors were isolated from animals and/or human blood donations—often contaminated with HIV or hepatitis virus , some patients had a negative reaction to the animal protein. • As of 1982 insulin production utilized bacteria that were engineered to make human insulin—pure and reliable. • Blood-clotting factors made in hamster cells using recombinant DNA technology began in 1990s
Some Products Made by Recombinant DNA Technology Table 14-1, p. 314
Human Proteins Can Be Made in Animals • Transgenic • The transfer of genes between species • Transgenic organism • An organism that has received a gene from another species by means of recombinant DNA technology
Human proteins made in animals Use recombinant DNA technology to express a human protein in the mammary glands of a cow, sheep, goat, (rabbits and hamsters used in early experiments) then patients drink the milk from these transgenic animals • For enzyme-replacement therapy as in Pompe disease • Blood-clotting factors for hemophiliacs • Collagen • Antibodies (vaccines)
Large Scale Synthesis of Human GAA-Pompe disease Rather than using an entire animal, only animal cells are used to make a recombinant protein for medical use. Fig. 14-3, p. 315
The Use of Transgenic Plants • Gene transfer into crop plants can result in the production of human proteins • Lower costs • Easier to grow • Using corn to make human collagen: http://www.inpharm.com/news/161608/us-team-make-human-biocollagen-plants
14.2 Using Stem Cells to Treat Disease • Embryonic stem cells: from the inner cell mass of early embryos. These cells are pluripotentand can form many different cell types.
Inner cell mass Fig. 14-4a, p. 316
Additional Classes of Stem Cells • Adult Stem cells: recovered from bone marrow or other organs. Can develop into a limited number of mature cells, thus are considered multipotent. • Induced plutipotent stem cells (iPS): adult cells reprogrammed by transferring several master control genes into the nucleus. They behave similar to embryonic stem cells.
Stem cell Based Therapies may Treat many Diseases • Can be used to replace defective cells Table 14-2, p. 317
Stem cell Based Therapy for the Treatment of Burns Fig. 14-8, p. 318
iPS cells from patients with specific disorders • Producing induced pluripotent stem cells from individuals with genetic diseases provides a way to study disease processes, scanning drug candidates for safety and effectiveness, or application to regenerative medicine • Examples include: • Huntington’s disease • Gaucher disease • Type I juvenile diabetes
14.3 Genetically Modified Foods • Transgenic plants are often referred to as either genetically modified organisms (GMOs) or genetically modified (GM) plants • Often more widely accepted in the US than in other nations. • Most likely over half of the food items you consumed today contained an ingredient from a GMO. 60% to 70% of foods in US supermarkets contain some transgenic plant material • Products made from corn, soybeans, cottonseed and canola oils most commonly contain transgenic ingredients
Foreign gene incorporated into a Ti plasmid Chromosomes inside plant-cell nucleus Bacterial chromosome The foreign gene is transferred into a plant cell. It becomes incorporated into one of the plant’s chromosomes. 1 Fig. 14-9a, p. 319
The plant cell grows and divides. Some of the descendant cells give rise to embryos that might go on to develop into mature, genetically engineered whole plants, as below. 2 Embryo Fig. 14-9b, p. 319
Transgenic Crop Plants can be made Resistant to Herbicides and Disease Fig. 14-10, p. 320
Transgenic Crop Plants can be made to Enhance the Nutritional Value of Foods • Golden rice contains increased levels of vitamin A Fig. 14-11, p. 320
Genetically Modified Crops Approved in the US Table 14-3, p. 320
Some Concerns About Genetically Modified Organisms • Are foods containing new proteins safe to eat? • Is it safe to eat food carrying part of a viral gene that switches on transgenes? • Can insect resistance genes be transferred to weeds or wild plants? • Can these plants have an unforeseen detrimental effect on the ecosystem? • Will pesticide-resistant insects develop?
14.4 Transgenic Animals as Models of Human Diseases • Transgenic mice are a common model system • Transfer of disease-causing human genes into mice creates mice that are used to study the development of human diseases and the effects of drugs and other therapies
Transferring Genes into Mammals • Microinjection of fertilized eggs Fig. 14-12, p. 322
Mouse model for Huntington’s Disease (HD) • HD mice are extremely useful as models of human neurodegenerative disorders • Used to study the progressive destruction of brain structures in early disease stages • Used to link changes in brain structure with changes in behavior • Used to screen drugs to improve symptoms or reverse brain damage
Some Human Diseases Studied in Animal Models Table 14-4, p. 323
DNA Profiles • Originally, minisatellites were used to make a DNA fingerprint, now STRs are used to create a DNA profile • Short tandem repeat (STR) • Short nucleotide sequences 2 to 9 base pairs long found throughout the human genome that organized into clusters of varying lengths • DNA profile • STR pattern used to identify individuals
DNA Profiles Can Be Made from Short Tandem Repeats (STRs) • STRs range from 2 to 9 base pairs in length • CCTTCCCTTCCCTTCCCTTCCCTTCCCTTC contains six repeats of the CCTTC sequence • Repeat numbers vary between individuals • A unique profile can be produced by analyzing several STRs in a DNA sample • In the US, a standard set of 13 STRs (CODIS) is used to prepare a profile (for more info see: http://www.fbi.gov/about-us/lab/codis/codis-and-ndis-fact-sheet)
DNA Profiles Are Used in the Forensics and Criminal Justice System • DNA profiles are used in more than 10,000 criminal cases per year. • Analysis of DNA profiles combines probability theory, statistics, and population genetics to estimate how frequently an allele combination is found in a population to calculate the probability that a single person will have that combination
A DNA profile from acriminal case • (Electrophoresis gel of PCR products) Size reference Size reference Size reference Size reference Control DNA Control DNA Control DNA Female cells Boyfriend Suspect 1 Suspect 2 Semen Victim Fig. 14-14, p. 324
Exploring Genetics: Death of a Czar • Forensics and several types of DNA evidence were used to confirm that bones discovered in 1991 belonged to Czar Nicholas Romanov II, his wife, and three of their five children who were killed during the Russian Revolution p. 325
14.6 Social and Ethical Questions about Biotechnology • Applications of recombinant DNA technology have developed faster than public policy, legislation, and social norms • Some issues that have arisen include: • Should genetically modified foods be labeled? • How much do animals suffer when used to make human proteins or used in disease models? • Who should have access to genetic information obtained from genetic testing? • Should we test for diseases for which there is no cure yet?