biology B1 (6)

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  • Created by: haidee
  • Created on: 30-04-12 20:04


  • Offspring look like their parents because of genetic information passed on to them in the gametes (sex cells) from which they developed
  • The information is contained it the chromosomes which are found in the nucleus of a cell
  • The information is carried by the genes DNA is a molecule from which chromosomes are made
  • Chromosomes found in pairs one inherited from my father and one from your mother
  • Each chromosomes in a pair carries genes which code for the same characteristics
  • Everybody is different even identical twins
  • Some of the differences are caused by our genes
  • Some differences are caused by the conditions in which we have developed many differences are caused by a combination of both

Plant tissue culture or micropropagation

  • A small number of cells is taken from a parent plant
  • The cells are transferred to a sterile jelly or liquid rich in nutrients and plant growth hormones
  • The cluster of cells will divide rapidly and develop roots and shoots
  • The tiny plantlets are transferred into plotting trays where they develop into plants
  • Cloning of plants has many important commercial implications
  • Successful varieties of plants can be produced commercially on a massive scale in a relatively short tome, enabling scientists to develop:
  • -fast growing crops that give more than one harvest in a year
  • -or crops with better disease-resistant qualities
  • Advantages of tissue culture:
  • -you can grow many plants in a small amount of time
  • -all the plants have the same genetic information so inherit the same desirable characteristics
  • -little space is needed and the conditions can be precisely controlled
  • Disadvantages to tissue culture:
  • -because they all have the same genetic information they are susceptible to disease or pests
  • -No variation means there is danger of reducing the gene pool
  • -No possibility of new beneficial characteristics by chance

Embryo cloning

  • At this very early stage of development every cell of the embryo can still form all of the cells needed for a new cow
  • They have not become specialised
  • Divide each embryo into several individual cells
  • Each cell grows into an identical embryos in the lab
  • Transfer embryos into their host mothers, which have been given hormones to get them ready for pregnancy
  • Identical cloned calves are born
  • They are not biologically related to their mothers

Adult cell cloning

  • A cell from the udder of one sheep is taken and the egg cell from another sheep
  • The egg


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