Genetic Engineering Lecture Notes PDF

LU2 Fig. 4.1 : Typical genetic engineering procedures with examples of applications  LU 2 Microbes and Genetic Engineering Lecture 5  Obtaining information from DNA for basic research and medical applications  Question What kind of informatio...

LU2 Fig. 4.1 : Typical genetic engineering procedures with examples of applications  LU 2 Microbes and Genetic Engineering Lecture 5  Obtaining information from DNA for basic research and medical applications  Question What kind of information can be obtained from cloned DNA ?  Information can be obtained from the process of DNA sequencing : determination of the exact sequence of nucleotide bases in DNA  Example  Identification and cloning of mutant gene that causes cystic fibrosis (CF)- oversecretion of mucus leading to blocked respiratory passageways  Sequence of mutated gene can be used as a diagnostic tool in hybridization technique called Southern Blotting  Southern Blotting  Human DNA is first digested with a restriction enzyme  DNA fragments are separated by gel electrophoresis  Separated fragments are transferred onto a filter by blotting  The fragments on the filter are then exposed to a radioactive probe  The probe will hybridize to this mutant gene but not to the normal gene.  Fragments to which the probe bound are identified by exposing the filter to X-ray film.  With this method, any person’ s gene can be tested for the presence of the mutated gene (causing CF).  Gene therapy  May provide cures for some genetic diseases  Defective or mutated gene can be transformed into normal genes  When these cells are returned to the person, they should function normally.  Forensic Microbiology  DNA fingerprinting – to identify bacterial or viral pathogens  Small amount of DNA can be amplified by a method called polymerase chain reactions (PCR)  PCR has been used as diagnostic tests to detect presence of infectious agents such as AIDS virus, SARS-corona virus, Cocksackie virus or the bacteria 0157: H7.  DNA chips and PCR microarrays that can screen a sample for multiple pathogens at once have been developed  Up to 22 primers from different microorganisms can be used to initiate the PCR  Agricultural application  Conventional plant crosses is laborious and time consuming  Genetically altered plants can be grown in large numbers; these plants can be induced to regenerate whole plants, from which seeds can be harvested.  Plant cells can be engineered by using Ti  has been engineered for enhanced nitrogen fixation  has been engineered to produce toxin against insects.  The can produce much more toxin than. It is added to the plant seeds and in time enters the growing plants.  Its toxin is ingested by the feeding borer larvae and kills them (harmless to humans)  PRODUCT COMMENT Agricultural Products – Lacks normal protein product that initiates ice-minus bacterium undesirable ice formation on plants Has toxin-producing gene from insect bacterium pathogen ; toxin kills root-eating insects that ingest bacteria bacterium Modified for enhanced nitrogen fixation Animal Husbandry products Porcine Growth Hormon Improves weight gain in swine; produced by Bovine Growth Hormon Improves weight gain and milk production in cattle; produced by Other Food Production Products Rennin Causes formation of milk curds for dairy products; produced by Cellulase Enzymes that degrade cellulose to make animal feedstocks; produced by Some agriculturally important products of genetic engineering  Crown gall disease on a tomato plant Tumor like growth is stimulated by a gene on Ti plasmid carried by , which has infected the plant.  Review question  Why is the Ti plasmid important to biotechnology ?  What is forensic Microbiology ?  Designer Jeans Denim Blue jeans  Made from cotton  Applying microbiology to develop environmentally friendly methods and lower production costs  Stonewashed denim (softer) - use enzyme cellulases; peroxidase producers from yeasts (cloned mushroom genes) used for bleaching  bacteria to make cellulose  Indigo dye – require high pH and produces waste that explodes in contact with air  Gene for conversion of indole to indigo from is placed into : turns blue  Plastic zippers produced by microbes (produces PHA, similar to plastic)  Labels – on paper made of cellulose produced by The Future of Genetic Engineering  May provide new treatments for disease and new diagnostic tools.  Have been used to map the human genome through the Human genome Project.  This will provide tools for diagnosis and possibly repair of genetic diseases  Risks and benefits of Recombinant DNA Technology  Constraints on recombinant DNA technology were relaxed due to the following observations: 1. No illness in laboratory workers could be traced to recombinants 2. The strain used in the experiments failed to infect humans who voluntarily received large doses 3. Incorporation of mammalian genes into was observed in nature, and these genes impaired the organism ability to adapt to environment - suggesting that if laboratory organisms did escape, they probably would not survive in the natural environment 4. Mutants of containing recombinant DNA were subject to control by accepted sanitary practices.