Gen Bio 2

• Genetic engineering


  Various techniques and procedures used in gene manipulation

  
• Recombinant DNA technology

  Refers to genetic engineering

  
• Natural DNA recombination occurs randomly during the crossing-over of homologous chromosomes during Meiosis I, during fertilization when two gametes fuse, or even through mutation
• DNA recombination, both natural and technology-manipulated, is being used to advantage in improving production of agricultural products, forensics, pharmaceuticals and medicine
• Genetic engineering compared to classical breeding

  • Genetic Engineering
  • Classical Breeding
• Genetic Engineering

  • Involves the use of molecular techniques to modify the traits of target organisms, often referred to as transgenic organisms or genetically modified organisms (GMO)
  • Genetic modification is achieved by adding a specific gene or genes or removing undesirable gene, to produce a desirable phenotype
  • The gene can be from the same species or different organism
  • Sometimes, the desired trait is attained faster than classical breeding

  
• Classical Breeding


  • Focuses on mating of organisms with desirable qualities
  • Relies heavily on the naturally occurring life cycle of organisms and homologous recombination to eliminate undesirable traits
  • Interbreeding can only be carried out with closely or distantly related organisms
  • It is time-consuming as breeding requires series of crossing and self-fertilization to be able to attain desired trait
• Tools used in Recombinant DNA Technology

  • Target DNA
  • Restriction enzymes
  • DNA cloning vectors
  • Host cell
  • Modifying enzymes

  
• Methods of Gene Cloning for DNA Recombination

  1. Isolation of target Gene

  2. Insertion of target gene into the vector

  3. Introduction of vector to the host cell

  4. Amplification of the target gene by the host cell

  
• Transgenic Organisms


  • BT Corn
  • Golden Rice
  • Transgenic Atlantic salmon
  • Transgenic Ruminants
  • Human insulin producing E. coli
  • Genetically modified Pseudomonas bacteria
• Gene


  The sequence of DNA that codes for a specific trait
• Allele


  The alternative forms of genes (minimum of two)
• Locus


  The location of the genes in the chromosomes
• Dominant


  The allele that is expressed in case more than one allele is present
• Recessive


  The allele that is not expressed in case more than one allele is present
• Homozygote


  A combination of similar alleles
• Heterozygote


  Combination of different alleles
• Genotype


  The combination of genes represented by letters
• Phenotype


  The appearance of the specified genotype
• Test cross


  Used to determine if an individual with dominant trait is homozygote or heterozygote
• Parental Generation (P)


  The first genotypes that are crossed

  
• First filial generation (F1)


  Generation after P
• Second filial generation (F2)


  Generation after F1
• Mendel's Law of Segregation

  • Alleles coming from the parents combine during fertilization, therefore there are two alleles per trait in an individual
  • During gamete formation (Meiosis), these pair of alleles will separate or segregate
  • When they are passed to the next generation, either but not both of the alleles are passed to one offspring
• Gregor Mendel


  Father of Genetics due to his discoveries on the passing of traits from one generation to another
• Mendel's garden peas experiment

  1. Revealed the concepts of heredity

  2. No concepts of nucleic acids and chromosomes at the time
• Mendel's Laws


  • Law of Segregation
  • Law of Independent Assortment
• Law of Segregation


  • Alleles coming from the parents combine during fertilization, there are two alleles per trait in an individual
  • During gamete formation (Meiosis), these pair of alleles will separate or segregate
  • Either but not both of the alleles are passed to one offspring
• Monohybrid cross (one trait)

  • Seed color of peas (yellow dominant, green recessive)
  • Genotypes and phenotypes of offspring

  
• Dihybrid cross (two traits)


  • Seed shape (round dominant, wrinkled) and seed color (yellow, green)
  • Genotypes and phenotypes of offspring

  
• Dihybrid cross (two traits)

  • Flower color (purple dominant, white) and seed shape (round, wrinkled)
  • Genotypes and phenotypes of offspring

  
• Law of Independent Assortment
• Genetic engineering