1. Artifical Selection

2. Artificial Selection
Artificial selection is the deliberate selection of organisms with desirable characteristics that are useful to humans 
Humans determine which alleles pass onto successive generations.

3. Selective breeding
Useful varieties of plants and animals have been derived from species by selective breeding

4. Selective breeding Cattle have been bred for Plants
Quantity and quality of meat
Milk yield
Butterfat content of milk
Plants
Increasing yield of crops
Disease resistance

5. Inbreeding depression
Reduction in variation of alleles in the population
Increase risk of homozygosity (harmful recessive genes)

6. hybridisation.
Hybrid
Individual resulting from a cross of two genetically dissimilar parents of the same species
Hybrid vigour – some offspring produced are stronger (“fitter”) than either parent.
Re-establishes heterozygosity.

7. Hybridisation in Farm Animals
Hybrid vigour in cattle
Improved birth weight
Improved feed conversion efficiency
Sheep
Scottish blackface x French strain
Hybrid has improved meat yield and quality

8. Genetic Engineering

9. Genetic Engineering (Recombinant DNA technology)
Genome haploid set of chromosomes typical of a species
Recombinant DNA technology involves transferring genes from the genome of one organism to the genome of another.

10. Location of genes
Recognition of characteristic banding patterns on chromosomes
Giant chromosomes take up stains producing distinctive bands
Banding pattern is a constant characteristic of each type of chromosome
Example – red/white eye colour in fruit fly
Gene probes
Short length of chemically labelled single sided DNA
Complementary to the gene that the genetic engineers wish to locate
DNA is cut into fragments and the gene probe attaches to required gene

11. Genetic Engineering Select a gene for desirable characteristics
Select a suitable vector
Splice the gene into the DNA of the vector
Insert vector into host cell
Host cell propagated

12. Enzymes involved Endonuclease Ligase
Used to cut DNA into fragments and open bacterial plasmids
Recognizes a particular sequence of bases on DNA and makes its cuts at these sites.
Ligase
Seals “sticky ends”
Seals DNA fragment into bacterial plasmid

13. Vector
Recombinant plasmids carry DNA from genome of one organism into that of another.

14. Antibiotic
Recombinant plasmid also contains a gene coding for anti-biotic resistance

15. Useful products Insulin production interferon
Human growth hormone production

16. Transgenic crops
 Agrobacterium tumefaciens can inject a plasmid into plant cells, the plasmid’s genetic material can become incorporated into the plant’s DNA.
Scientists use this bacteria to insert desirable genes into plants. These plants are transgenic varieties.
e.g. gene inserted to produce an insecticide protein, the leaves of the plant can resist attack by caterpillars.

17. Crop plants Other inserted genes in plants
block production of chemicals which promote ripening
resistance to weed killer
production of antifreeze chemical
block enzyme production
ability to fix nitrogen
resistance to drought

18. Farm animals genetically modified to produce human proteins Examples
blood clotting factor
Eggs that contain anti-bodies needed for cancer fighting drugs

19. somatic fusion
Somatic fusion allows a fertile hybrid to be formed from two species.
Protoplasts from two different species are prepared by having their cell walls removed.
These protoplasts fused to form hybrid protoplast.
Somatic hybrid cell is induced to form a cell wall
Hybrid cell divides into a callus (undifferentiated cell mass)
Calluses develop into hybrid plants containing mixture of parents’ genetic traits.

20. Resistance to potato leaf roll
Through somatic fusion a potato plant has been produced which is tuber bearing and resistant to potato leaf roll virus.