Option B.2 - Biotechnology in Agriculture Essential Idea: Crops can be modified to increase yields and to obtain novel products

A few terms that will help discuss these applications: Transgene = gene that has been moved not just from one organism to another (i.e., via gene modification or gene transfer) but also to a new species. (further questioning the solidity of the definition of “species”?) Proteome = the total of all proteins in a given species (recall the diverse set of functions that proteins can serve??) Target gene = the gene of interest that is inserted into the recipient genome Vector = a plasmid or a virus that acts as a carrier and directs a target gene into a new genome (how is this like the use of the term in physics?) Open Reading Frame = a stretch of DNA that has a start codon (ATG) and no extra stop codons and sufficient nucleotides to make the necessary size protein Bioinformatics = using computer science and IT to organize, study and manipulate known DNA sequences

Transgenes are part of an artificial construct that is to be introduced and expressed in a new organism. The promoter is where the RNA polymerase binds to initiate transcription note: often these constructs have the marker gene under the regulation of the same promoter as the transgene...the order would then be PROMOTER - MARKER GENE - TRANSGENE - TERMINATION SEQUENCE

Why does agriculture deserve attention/modification? FOOD FOR THE NINE BILLION - EXPECTED POPULATION BY 2050 FOUR TIMES THE POPULATION IN 1950 - MALTHUS’ PREDICTION CROP YIELDS ARE GREATLY LIMITED BY ENVIRONMENTAL FACTORS (recall the main factors that limited the rates of photosynthesis?) - INSECTS/FUNGAL PESTS - VIRAL INFECTIONS - WEEDS (COMPETITION BY UNDESIRABLE PLANTS) - DROUGHT MODIFIED CROPS CAN YIELD VALUABLE MEDICAL, INDUSTRIAL PRODUCTS - PHARMACEUTICALS - ENZYMES - VITAMINS - VACCINES

Examples of transgenic plants Glyphosate-resistant soybeans: glyphosate (“Roundup”) is a short-lived herbicide that non-specifically kills weeds, allowing the the resistant soybean to survive and outcompete the weeds Agrobacterium is a plant disease causing bacteria. It has a plasmid called Ti (tumor inducing) which integrates into the genome of the plant cell. THINK OF BACTERIAL PLASMID VECTORS AS BIOLOGICAL METHOD OF TRANSFORMATION

Another case study - Hepatitis vaccine from tobacco Hepatitis is an epidemic-causing infectious disease, especially in the developing world. Previous vaccine preparations were made in yeast and required refrig- eration, making it prohibitively expensive. The method for introducing the gene for an antibody to hepatitis (I.e., a vaccine) into tobacco uses a disarmed retrovirus as a vector. The plants do not die, but produce great amounts (tobacco is surprisingly large) of vaccine. Model of TMV - showing the internal RNA as green and the protein coat as pink. RNA containing viruses are called “retro” because they rely on reverse transcriptase. What is the reverse of transcription? SIMILARLY TO PLASMIDS, THINK OF VIRAL VECTORS AS BIOLOGICAL METHOD OF TRANSFORMATION

Potato starch from Amflora potatoes Amylopectin (highly branched structure) is a highly valuable starch used in the production of high quality paper and critical construction adhesives. Most potatoes are only 80% amylopectin and 20% straight chain amylose. These transgenic potatoes are 100% amylopectin. Despite the fact that these are not used for food and the they were approved by the regulatory agency of the EU, these Amflora potatoes are no longer sold in the European market.

Further examples of products and tools Bt corn - allows reduced use of fungicides Salt tolerant peanuts - can grow in land that would not have been fertile Virus-resistant papaya Drought tolerant corn In addition to plasmids & viruses… - Microinjection (tiny needles through plasma membrane -removing cell wall with enzymes, making protoplasts) - Electroporation (electrical impulses on protoplasts) - Ballistics - yep, shooting plants with DNA-coated particles

Ballistics (as in guns):

Steps in using plasmids - into chloroplasts Ballistics used to “shoot” DNA- coated particles into plant cell Some chloroplasts pick up new DNA & new gene expression (white vs. green) Asexually clone these into new individual plants Select those regions of the leaf with specifically white sectors

Steps in using plasmids - into cells 5. The recombinant plasmid is introduced into plant cells in culture 6. A plant is regenerated with the new gene expression of the target gene.

Two more methods of modifying plants with chemistry TRANSFECTION - USING CALCIUM AND PHOSPHATE SALTS TO NEUTRALIZE THE CHARGE OF DNA AND ALLOW IT TO BE TAKEN UP BY PHAGOCYTOSIS LIPOSOMES - LIPID SACS THAT ARE AQUEOUS (WATER-BASED) ON THE INSIDE