GCSE biology

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Author:
ghoran
ID:
150923
Filename:
GCSE biology
Updated:
2012-04-30 12:10:45
Tags:
genetic variation
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  1. The population of the eart is more than 6 billion people , and no two individuals except for indentical twins are gentically the same
    people are different because they
    inherit different characteristics from their parents
  2. each child carries a
    unique set og genes half from its mother and half from its farther
  3. a persons unique characteristics are caused by
    • the set of genes they inherited from their parents
    • the environment in which they developed
  4. some characteristics , such as eye colour and earlobe shape , are only determined by genes . these are called
    inherited characateristics
  5. other types of characteristics suh , ach as scars and hair lenght are not inherited but dependant on eneivonmengtal factors . these are called
    aquired chracteristics
  6. characteristics are due to
    a combination of both inherited and environmental factrors
  7. characteristics can be classifed in diffrent ways
    • a feature that can be measured and gen a value from a rangive of values shows continious variation
    • a feature tha cannot be measured but is one of a few distinct options shows discontionous variation
  8. mutations can arise spontaneosly ; for example through the incorrect copying of base pairs during DNA replication , or the unequal distribution of chromosomes during cell division .
    Mutations can also be caused by environmental factors , such as radiation and certain chemicals . these factors are called
    mutagens
  9. some mutations may be benificial but many are harmful and increase the risk of diseases such as
    cancer
  10. there are two types of reproduction
    • asexual
    • sexual
  11. animals and plants reproduce to make
    nes individuals
  12. in asexual reproduction this is only
    one parent
  13. in asexual reproduction all the offspring are
    identical to the parent they are clones
  14. in sexual reproduction there are
    2 parents
  15. in sexual reproduction the parents have sex organs , which
    produce sex cells called gametes
  16. the male gamete is called
    sperm
  17. female gamete is called an
    ovum
  18. during sexual reproduction at fertilisation an ovum and sperm join together to form a
    zygote
  19. sexual reproduction produces
    offspring that show variation
  20. the nucleus of the sperm and and the ovum contain
    thread like structures called chromosomes
  21. chromosomes are found in
    pairs . Humans have 23 pairs of chromosomes
  22. chromosomes are made up of
    thousands of genes
  23. genes control
    all the inherited chracteristics
  24. each gene is made up of a
    short piece of DNA
  25. describe the stages in embryo transplant , using cows as an example
    • sperm is taken from the best bulls
    • eggs are taken from the best cows
    • fertilisation in a petri dish
    • fertilised egg grows into an embryo
    • the cells of the embryo are slpit apart
    • each cell develops into a new embryo
    • the embryos are placed in wombs
  26. describe the stages in adult cell cloning using a sheep as an example
    where sheep A is the animal to be cloned and sheep B is the eg donor
    • cell from sheep A is taken from the udder , the nucleus is removed
    • eggs are taken from sheep B , the egg cell is enuculated
    • the nucleus from sheep A is inserted into the enuculated egg cell (sheep B's cell) which creates a diploid cell that grows like a zygote
    • implanted into a surrogate mother
    • cloned sheep
  27. decsribe tissue culture
    • a plant with desired charateristics is selected
    • the stem is cut into pieces , each with a bud
    • each explant is steralised in bleach solution
    • under sterile conditions the explants are transfered to agar
    • the explants grow and shoots and roots develop
    • after 3-4 weeks the plantlets are potted in sterile compost
  28. what are the advanatages of adult cell cloning
    • it will protect endangered species
    • clones could be used as donors
    • cloning could improve the food supply
  29. what are the disadavantages of adult cell cloning
    • because an "old nucleus" is used it may cause deformities in the offspring as it may have aged or developed faster thatn it should have done
    • the technology is not developed it has a low sucess rate as seen with dolly the sheep
    • in the future there woul be a loss of variation
  30. what are the disadvantages of cloning humans
    • doctors may taget humans for clones
    • a clone may end up having fewer rights than other people
    • clones may be created for specific reasons e.g. slavery
    • unethical and immoral
  31. genetic engineering uses
    enzymes to cut and paste genes
  32. explain the process of genetic engineering
    • the basic idea is to copy a useful gene from one organism's chromosome into the cells of another
    • a useful gene is cut from ones organism's chromosome using enzymes
    • enzymes are then used to cut another organism's chromosome and then to insert the useful gene
  33. describe genetic engineering of bacteria to produce human insulin
    • human cell with insulin gene
    • enzyme cut from DNA using an enzyme
    • bacteria plasmid cut withe same enzyme
    • insulin gene inserted into bacteria plasmid
    • the plasmid is the vector that puts the insuline genes into the bacterium
    • plasmid multiplies in the bacterium and the bacteria reproduce rapidly
    • insulin collected
  34. what can insulin be used for
    can be used in njections for diabetics

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