Selective Breeding Over 1000’s of years mankind has grown plants and domesticated animals. Characteristics have been selected for repeated breeding e.g - milk yield in cattle - meat yield in poultry and cattle - woolly fleece in sheep - corn seeds with high oil or protein content Only members of a species with the required characteristic are allowed to breed

Genetic Engineering - Bacterium Each cell has a complete chromosome and a plasmid Plasmid and chromosomes are made of genes Each gene makes up one protein (e.g enzyme - which then controls one specific reaction) Cell activity depends upon chromosomes e.g. One gene could make lactase to help bacteria break down lactose

Genetic Engineering Transfer of pieces of chromosomes from one organism to another e.g. human to bacterium Reprogrammed cell becomes a factory for the required product e.g insulin Several stages involved

Advantages of using reprogrammed bacteria By transferring a piece of chromosome, the organism receiving the material is being manipulated Advantages: Much easier (& cheaper) to mass produce bacteria cells, than to clone and mass produce complex organisms e.g. humans Mass quantities of a useful product e.g insulin can be produced

Genetic Engineering v Selective Breeding Both can alter the genetic makeup of a species for scientific benefit Selective Breeding Requires years of careful selection & breeding Doesn’t always produce the ideal organism Only animals that would normally produce the required product can be used

Benefits of Genetic Engineering Allows scientists to directly alter the genotype of a species by manipulating it’s chromosomes Altered organism has a new genotype suited to mankind’s needs Allows for a species to be programmed to make products previously only made by another species E.g. bacteria producing human insulin

Applications of Genetic Engineering Medical - copy table 10.2 on pg. 208 Commercial - - Bacteria can be used in detergents to digest stains, or to make antifreeze (ethylene glycol) - Yeast for beer making can be modified to produce more alcohol, but fewer carbs - Cheese making: rennin curdles milk, normally from calf stomach linings. Can now be produced by yeast cells

Transgenic multicellular organisms Genetic engineering on more complex organisms Agrobacterium tumefaciens - soil bacterium that injects a plasmid into plant tissue (‘natural genetic engineer’) Genetic material from plasmid is incorporated into the plants DNA. Plant expresses bacterial genes Scientists have altered the plasmids so the bacterium inserts useful genes into the plant DNA These are Transgenic plants

Transgenic Plants Plants that have gained new genetic material from foreign DNA At present the benefits to certain plants have included extended shelf life in apples & tomatoes, resistance to weedkiller in soya crops, pea plants that produce their own insecticide

Transgenic organisms - future Cereals : hoped that in future cereal crops will be modified to contain genes for certain characteristics e.g resistance to herbicides, drought, pests, micro-organisms & salinity/ increased photsynthetic rate Future - animal genes into plants e.g already haemoglobin grown in tobacco plants