GCSE A* REVISION NOTES


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B1.7: Genetic variation and its control

B1.7.1: Why organisms are different

Inheritance

Inherited Differences in humans

Genetic Variation

Environmental Variation

B1.7.2:  Reproduction

Asexual reproduction

Sexual Reproduction

Cloning in Animals

Pros
Cons
Embryonic Cloning
  1. Sperm is taken from a bull of a high yield dairy herd
  2. Cow is artificially inseminated with sperm
  3. Zygotes develop into embryos in cow and then are then removed from the uterus
  4. Embryos are split into several smaller embryos
  5. Each of these is placed in the uterus of a foster mother
  6. The calves born are genetically identical to each other
Adult Cell Cloning
  1. body cell is taken from sheep A
  2. DNA is extracted from cell
  3. Egg cell is taken from sheep B
  4. The nucleus is removed (nucleated)
  5. The DNA from sheep A is fused with the egg cell from sheep B
  6. Egg is given small electric shock to start it replicating
  7. Egg cell develops into embryo which is placed in the uterus of the foster mother
  8. Lamb is a clone of sheep A

Cloning in Plants

Pros
Cons
Cuttings
Tissue Culture

Genetic Engineering

Recombinant DNA – DNA altered during genetic engineering

Transgenic Organism – An organism produced via splicing

Insulin Production
  1. DNA removed from human pancreas cell
  2. The specific gene controlling insulin production is isolated
  3. The gene is ‘cut out’ of the DNA using restriction enzymes
    1. This leaves them with sticky ends
  4. Plasmid is removed from bacterial cell
  5. DNA is cut using restriction enzymes so it has sticky ends
  6. Human insulin gene is inserted into the bacterial DNA using ligase enzymes
  7. The recombinant DNA is inserted back into the bacterial cell
  8. The bacterial reproduces asexually and produces clones with the insulin gene
GMO’s

We genetically engineering:


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