b6.2 Flashcards
describe some of the biological factors affecting levels of food security
increased human population
changing diets- wealthier people tend to eat more varied, more meat, energy intensive than plant
climate change- increases in atmospheric carbon dioxide may lead to increasing yields of some crops
new pests and pathogens may evolve
selective breeding
breeding other animals and plants for particular characteristics
to produce highest yields, farmers choose best plants/ animals to breed from
can also produce crops with high resistance to disease
how does a farmer selectively breed organisms
decide which characteristic of the species is desirable
select parents with high levels of this characteristic
breed from these individuals
select the best offspring and breed again
repeat for many generations
disadvantages of selective breeding
reduces number of alleles (gene pool) of a species, reducing variation
therefore if new disease arises, may not be an organism that contains allele for resistance
species may become extinct
increases chance also of inheriting genetic disease
hydroponics
method of growing plants without soil- water containing dissolved minerals
sustainable food production
producing food in ways that can be continued indefinitely
biological control
when farmers use relationship between natural predators and crop pests to kill pests
what is genetic engineering
altering an organisms genome to produce an organism with desired characteristics, very accurate, single genes can be targeted, can occur in one generation
examples of genetically engineered
cotton - to increase crop yield from the same area of land
corn- to produce toxins that kill insects, makes plant resistant to pests, less pesticides needed
bacteria- produce medical drugs such as insulin or drugs to treat disease in domesticated animals
how are genetically ENGINEERED organisms produced
to make organism with desired characteristic, genes are taken from another organism that code for this character (foreign genes)
put these into plant/animal cell at early stage of organisms development
as it develops, displays characteristics coded for by foreign genes
risks of genetic engineering
don’t know longterm effects
may lead to health problems if eaten (new allergens?)
genetically engineered crops may cross pollinate with wild plants, introducing the new gene into wild plants, disrupt ecosystem balance
unethical- interfering science w nature
how does genetic engineering an organism acc work
identify genes that code for desired characteristic
remove gene from donor organism
insert gene into host organism (bacterium)
host will now display characteristics
how to genetically engineer bacteria
restriction enzymes cut the donor DNA at specific base sequences
make a staggered cut, leaving few exposed unpaired bases on ends of DNA strands (sticky ends)
same restriction enzymes also used to cut open bacterial plasmid
ligase enzymes then rejoin DNA strands at sticky ends
since both host and donor DNA have same sticky ends, new gene is joined into the plasmid DNA
do cells always incorporate foreign genes
insert an antibiotic resistance gene into the plasmid at the same time as inserting the gene coding for desired characteristic
transfer bacteria to agar plate with selected antibiotic. incubate and allow time for bacteria to grow
any bacterial colonies present will survive because they now contain AR marker gene. these bacteria will also contain desired gene
what are GMOs
created when foreign genes are transferred into an organism
genetically modifyin organism
plasmids bacteria and virus can all be used as vectors to transfer foreign dna
