Biology 4.2

• Chromosomes


  Found in the nucleus of cells, made up of hundreds of genes which are sections of DNA
• We all have the same genes for characteristics, but the differences in the genes lead to differences in appearances</b>
• Alleles


  Variations of the same gene
• Chromosomes


  Come in 23 pairs or 46 in total, long strands of DNA
• Gene


  A section of DNA which is the code for a certain characteristic
• Chromosomes come from the mother (23) and the father (23)
• Cancer cells


  Divide uncontrollably, producing a growth called a tumour
• Factors linked to cancer

  • Viruses (e.g. HPV)
  • Smoking cigarettes
  • Exposure to chemicals
  • Exposure to UV light
  • Poor diet
• Genetic factors


  Can increase the possibility of cancer, especially as you age and more mistakes are made during mitosis
• Removal of cancer


  1. Medication (chemotherapy)

  2. Cutting out the tumour

  3. Exposure to radiation
• Mitosis


  Replaces lost or damaged cells or tissue, allows growth by dividing into an identical copy of itself
• Daughter cells


  The two cells produced when the mother cell divides, they have the same genetic information
• Meiosis


  How parents reproduce sexually, the male gamete (sperm) fuses with the female gamete (egg) to produce a new cell (zygote or baby)
• Daughter cells (meiosis)


  The four non-identical cells produced, they have half the genetic information of the mother cell
• Stem cells


  Cells that have the ability to become a different type of cell, the first cell that formed us in the embryo was a stem cell
• Embryonic stem cells


  Undifferentiated cells that haven't become specialized
• Adult stem cells


  Can only differentiate into cells of a related type, e.g. bone marrow stem cells can differentiate into blood cells
• Uses of stem cells in humans

  • Treat burn injuries by growing new skin
  • Treat blood diseases by growing healthy red blood cells
  • Transplanted from the patient to avoid rejection
• Clinical issues with stem cell use

  • No guarantee of success
  • Difficulty finding donors
  • Difficulty obtaining/storing patient's embryonic stem cells
  • Mutations observed in cultured stem cells
  • Stem cells could be contaminated with viruses
• Ethical issues with stem cell use

  • Is it morally right to use life as an experiment?
  • When should an embryo be considered a person?
• Social issues with stem cell use

  • Educating the public
  • Whether benefits outweigh risks
  • Patients can be exploited or given false hope
• Meristems


  Regions in plants where stem cells are located, can differentiate into all types of plant cells
• DNA profiling


  1. Isolation of DNA

  2. Fragmentation of chromosomes

  3. Separation of DNA fragments by electrophoresis

  4. Comparison of DNA profiles
• Uses of DNA profiling

  • Solving crimes
  • Paternity tests
  • Identifying individuals
  • Classification of species
  • Early detection of diseases
• Ethical issues with DNA profiling

  • Privacy concerns if DNA is kept by police
  • Insurance companies may be informed and deny coverage