PowerPoint Presentation Materials to accompany Genetics: Analysis and Principles Robert J. Brooker CHAPTER 19 BIOTECHNOLOGY Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

INTRODUCTION Biotechnology is broadly defined as technologies that involve the use of living organisms, or their products, to benefit humans It is not a new topic It began about 12,000 years ago when humans began to domesticate animal and plants for the production of food Since the 1970s, molecular genetics has provided new, improved ways to make use of organisms to benefit humans An organism that has integrated recombinant DNA into its genome is called transgenic 19-2 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

19.1 USES OF MICROORGANISMS IN BIOTECHNOLGY Microorganisms are used to benefit humans in various ways Molecular genetic tools are very important in influencing and improving our use of microorganisms Overall, the use of recombinant microorganisms is an area of great research interest and potential However, there are problems such as safety concerns and negative public perception 19-3 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

The Genetic Engineering of Plants Is Easier Than That of Animals Plant advantages: 1) they are easier to clone than animal cells (plant cells are totipotent: one cell can produce an entire plant); 2) they can be grown in vast fields which allows massive production of desired products;

Transgenic plants Molecular biologists use the bacterium Agrobacterium tumefaciens which naturally infect plants to produce transgenic plants. Molecular biologists can genetically engineer plants that can: synthesize animal or plant proteins; resist herbicides; resist infection by plant viruses.

Gene Addition versus Gene Replacement Cloned genes can be introduced into plant and animal cells However, the gene will not be inherited stably if it does not become integrated into the host cell’s genome This integration occurs by recombination The introduction of a cloned gene into a cell can lead to one of two outcomes Gene replacement Gene addition Refer to Figure 19.5 19-26 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

If rendered inactive by mutation => gene knockout Figure 19.5 19-27 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Production of Mice That Contain Gene Replacements In bacteria and yeast, gene replacement is the common outcome These have relatively small genomes, so homologous recombination occurs at a relatively high rate In complex eukaryotes, gene addition is the norm These have very large genomes, so homologous recombination is rare Only 0.1% of the time 19-28 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

This approach is shown in Figure 19.6 To produce mice with gene replacements, molecular biologists have resorted to trickery Cells in which homologous recombination has occurred are preferentially selected This approach is shown in Figure 19.6 The cloned gene is altered using two selectable markers A neomycin-resistant gene (NeoR) is inserted into the center of the coding sequence of the target gene A thymidine-kinase gene (TK) is inserted adjacent (not within) the target gene TK renders cells sensitive to killing by a drug called gancyclovir The modified target gene is then introduced into mouse embryonic cells which can be grown in the lab 19-29 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Use of Gene Replacements in Mice Gene replacements were discussed in Figure 19.6 When a mouse is homozygous for an inactivated gene, this is called a gene knockout The inactive mutant gene has replaced both copies of the normal gene Gene replacements and gene knockouts have become powerful tools for understanding gene function 19-53 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

The production of proteins from mammals is more advantageous than the from bacteria 1. Certain proteins are more likely to function properly when expressed in mammals Post-translational modifications occur in eukaryotes Degradation and misfolding occur in bacteria The strategy for expressing human genes in animals is shown in Figure 19.13 19-57 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

And use it to treat humans Figure 19.13 19-58

19.4 DNA FINGERPRINTING DNA fingerprinting is a technology that identifies particular individuals using properties of their DNA It is also termed DNA profiling The application of DNA fingerprinting to forensics has captured the most public attention In addition, DNA fingerprinting can also be used to determine if two individuals are genetically related For example, it is used routinely in paternity testing 19-62 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

When subjected to DNA fingerprinting, chromosomal DNA gives rise to a series of bands on a gel Refer to Figure 19.19 The order of bands is an individual’s DNA fingerprint It is the unique pattern of these bands that makes it possible to distinguish individuals 19-63 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

RFLPs as markers for disease-causing alleles RFLP marker DNA Disease-causing allele Normal allele

Uses of DNA Fingerprinting Within the past decade, the uses of DNA fingerprinting have expanded in many ways In medicine, it is used identify different species of bacteria and fungi and also different strains of the same species This is useful for appropriate antibiotic treatment DNA fingerprinting is also used in forensics and relationship testing 19-69 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Male 2 does not have many of the child’s paternal bands Therefore he cannot be the biological father Male 1 has all the child’s paternal bands The probability of this occurring by chance alone is very small Therefore he is the biological father Figure 19.19 The use of DNA fingerprinting to establish paternity 19-71 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

DNA fingerprints from a murder case Defendant’s blood (D) Blood from defendant’s clothes Victim’s blood (V) D Jeans shirt V 4 g 8 g