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Chapter 14

FOOD 2010 Chapter Notes - Chapter 14: Rhizobium Rhizogenes, Genetically Modified Crops, Dna Ligase


Department
Food Science
Course Code
FOOD 2010
Professor
Massimo Marcone
Chapter
14

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Chapter 14 - Food Biotechnology
14.1 What is Food Biotechnology
-refers to the technology of manipulating or modifying deoxyribonucleic acid for the
purpose of improving the quality and/or safety of food
-surmounting the species barrier
-cross-breading plants - can only take place with very closely related species
-backcrossing - taking the new crop with the parent one repeatedly to breed out
unwanted characteristics
-in short, results from traditional cross-breading technology are random,
difficult to control, often imprecise, and time-consuming
-benefits of food biotechnology
-has the potential to address broad global food issues
-alleviating food shortages in developing countries
-minimizing the impact of food production on the environment
-improving the nutritional health of populations
-rotting time of foods can be delayed
-crops can withstand harsh conditions
-disease resistant plants could be created
-crops can have an increased nutritional value
14.2 Genetic Engineering
-genetics = field of study concerned with the elements in nature responsible for passing
down traits from one generation to another
-bacteria don't have nuclei, they have DNA wound up in a tight coil called "bacterial
chromosome
-they also have small circular rings of DNA called plasmids
-genetic engineering = manipulation of genes and the organisms containing them
-protein synthesis
-BIO Tchu Notes
-genetic code is universal = transferring genes from one organism to another is
possible
-manipulating DNA in Food production
-restriction enzymes (cutting in the right place found in bacteria)
-DNA ligase (helps form chemical bonds that will join two DNA strands)
-using messenger RNA in Genetic Engineering
-RNA is used as its easier to manipulate instead of DNA
-DNA is made from the RNA using reverse transcriptase so that restriction
enzymes can be effective
-DNA polymerase is used to create the second strand of DNA
-inserting DNA into bacteria
-for insertion of DNA into microorganisms plasmids are used to carry the gene
into the cell
-inserting DNA into cells
PLANT CELLS
-ballistic bombardement is used
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Chapter 14 - Food Biotechnology
-DNA is first pasted onto microscopic gold or tungsten particles
-then are then shot into plant tissue at high velocity using a "metal gun"
-electroporation can also be used
-electric field is applied to target cell in a series of pulses
-momentarily pores appear on the membrane of a cell allowing DNA to
enter the cell
ANIMAL CELLS
-microinjection is used
-DNA injected into fertilized egg cells through a pipette
-egg cells are used to introduce new genes early in an animals
development
-eggs are then inserted into uterus of surrogate mother, allowing normal
development
-screening cells for gene insertion
-marker genes - code for an easily recognizable product, and inserted into cells at
the same time as the desired gene
-if the one gene is taken up then so is the marker gene
-PCR and genetic probing
-polymerase chain reaction and genetic probing is used
-PCR used to generate many copies of DNA in a shortish time
-Genetic probe can be used to detect the presence of the DNA
-Gene expression through Genetic Switches
-genetic switches - confirm that the cell receiving the desired gene has the ability
to express that gene and to synthesize the product coded by the gene. Genetic
switches are needed to trigger expression of other genes
-propagating growth of genetically engineered cells
-genetically engineered plant tissue is usually grown in cell culture
-infection with Agrobacterium rhizogenes that cause hairy root cultures can help
eliminate the need for traditional field planting methods
-cloning is a variation of genetically modified embryos, where each embryo is
split into 8 cells, each cell is implanted into a surrogate resulting in 8 identical
animals that contain the desired genetic trait
SEE PG 398 for summary of process
14.3 Regulations Controlling the Application of Food Biotechnology
-food regulations see chapter 7
-this section will focus on regulations for biotech foods
-FDA policy
-genetic modification - products resulting from insertion must be predictable
- stability of the insertion must be guaranteed
-genetic rearrangements must be minimized
-toxicants -not allowed to create toxic substances
-nutrients -nutritional value can be changed but only in a positive way
-nutrients must be bioavailable
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