STEM CELLS

• HOW ARE GENES PREVENTED FROM EXPRESSING?

  • preventing transcription therefore preventing mRNA production
  • preventing translation
• WHAT ARE STEM CELLS?

  unspecialised cells which are able to divide by mitosis and differentiate to become a specialised cell as they can express all genes
• ORIGINS OF DIFFERENT STEM CELLS?

  • embryonic
  • umbilical cord blood
  • placental
  • adult (specific to a particular tissue/ organ)
• TYPES OF STEM CELL?

  TOTIPOTENT

  • early embryo
  • can differentiate into any cell
  • zygote stem cells

  PLURIPOTENT

  • embryo
  • can differentiate into any cell except extra embryonic cells (placenta)
  • embryonic/ fetal stem cells

  MULTIPOTENT

  • adult
  • can differentiate into a limited number of cells
  • for example, stem cells in bone marrow can differentiate into any blood cell
  • adult/ umbilical cord blood stem cells

  UNIPOTENT

  • adult
  • can differentiate into one type of cell
  • cardiomyocyte cells
• INDUCED PLURIPOTENT STEM CELLS (iPS CELLS)?

  • pluripotent cells
  • produced from unipotent cells in the lab
  • genetically altered by inducing genes and transcriptional factors
  • capable of self-renewal
  • overcome ethical issues of embryo usage
• EXAMPLES OF USES OF PLURIPOTENT CELLS IN TREATMENT?

  1. Heart muscle: heart damage (e.g. result of a heart attack)
  2. Skeletal muscle: muscular dystrophy
  3. Beta cells of pancreas: type 1 diabetes
  4. Nerve: Parkinson's, multiple sclerosis, strokes, Alzheimer's, paralysis due to spinal injury
  5. Blood: leukaemia, inherited blood diseases
  6. Skin: burns and wounds
  7. Bone: osteoporosis
  8. Cartilage: osteoarthritis
  9. Retinal: macular degeneration
• WHAT ARE TRANSCRIPTIONAL FACTORS?

  proteins which control gene expression by switching genes on or off
• HOW DO TRANSCRIPTION FACTORS WORK?

  • bind to promoter
  • cause gene to be turned on
  • RNA polymerase is able to bind
  • catalyses transcription
  • produces mRNA
  • translation creates a protein