Biology - B1.6 - Variation, Reproduction and New Technology

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B1.6.1 - Inheritance

  • Cell nuclei contain chromosones, which carry genes
  • In the nucei of sex cells (gametes) there's only a single set of chromosones, so the nuclei of both a male and female sex cell would contain one set of genes
  • Genetic information is passed from parents to offspring, so the offspring have two sets of genes inherited from both parents
  • Different genes = control different characteristics
  • Chromosones are in pairs - one from each parent
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B1.6.2 - Types of Reproduction

  • Asexual reproduction - gametes don't fuse, genetic information all from one parent, offspring identical to parent - little variation, identical copies that are formed called clones
  • Sexual reproduction - gametes fuse, mixing of genetic information - variation, sex cells (in animals) - sperm and egg, offspring similar to both parents but not identical - have two sets of genes
  • Random mixing of genes = variation - important for survival as some characteristics give offspring better chance of surviving in difficult conditions
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B1.6.3 - Genetic and Environmental Differences

  • Different characteristics due to - genes, conditions and combination of both
  • Genes are the most important factor in controlling appereance
  • Plants affected by - light, nutrients and space - weaker plants with the same genes as a stronger plant but wouldn't grow as well
  • Human development affected during pregnancy - mother smoking or drinking can cause the baby to have a small birth weight
  • Too little/much food alter characteristics - eg. genes determine potentential to be an athlete but training and diet will also alter the body
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B1.6.4 - Cloning

  • Clones - identical to parent
  • Cloning animals is harder than clonign plants
  • Used to produce new and useful, in farming and agriculture, individuals
  • Plant cloning -> cheap and effective - take cutting and grow it, or, more expensive - take small group of cells and grow them under special conditions (tissue culture) - used to reproduce large numbers of rare or top quality plants
  • Animal cloning -> embryo transplants - embryo with unspecialised cells spilt into smaller groups of cells, each group is transplanted and allowed to develop in a host animal
  • Can be genetically modified, before cloning, to produce useful substances
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B1.6.5 - Adult Cell Cloning

  • Adult cell cloning - nucleus of adult cell (eg. skin cell) replaces nucleus of an egg cell - nucleus taken out of unfertilised egg -> nucleus from skin cell removed and placed inside 'empty egg' - > electric shock to start division -> ball of cells called embryo -> ball of cells put into womb of host mother
  • Embryo is genetically identical to to adult skin cell
  • Dolly the sheep - produced by adult cell cloning in 1997
  • Adv - cloned animals can be genetically engineered to have medical uses, can save animals from extinction
  • Disadv - ethical concerns, limits gene pool - cause problems for natural selection if environment changes, concerns about using it on humans in the future
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B1.6.6 - Genetic Engineering

  • Genetic engineering - changing genetic make-up of organism
  • Genes can be transferred to animal, plant and microorganism cells at an early development stage
  • A gene is cut out of chromosone using enzyme -> gene placed in chromosone of another organism
  • Genes can be put in organism of same species for desired characteristics or a different species, eg. a bacterium - gene to produce human insulin can be put in bacteria, which can produce large amounts of insulin to treat diabetes
  • Genes can be transferred to crop plants - crops with changed genes = genetically modified (GM) crop plants - Gm crops can be insect/herbicide-resistant and usually have increased yields
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B1.6.7 - Making Choices About Technology

  • Adv and disadv in using clong and genetic engineering
  • Adv - clonging cattle = herds of cattle with useful characteristcs, adult cell cloning - copies of the best animals (eg. race horses), faulty gene = genetic disorder - correct gene transferred = cure, medical drugs been produced by genetic engineering (eg. insulin and antibodies), GM crops - insect/herbicide-resistant
  • Disadv - GM crops are infertile - farmer has to buy new seeds each year, concerns about introducing genes to wild flowers, non-pest insects affected by GM crops, effect o eating GM crops on human health, ethical? - long term effects, creating new organisms, ethically correct
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This is actually amazing! Thanks for this :)

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