Regulation of gene expression

• What is a stem cell

  A stem cell are undifferentiated cells that can divide (by mitosis) an unlimited number of times and become specialised
• What is potency?

  The ability of a stem cell to undergo differentiation
• what are the three types of potency ?

  totipotency

  pluripotency

  multipotency
• What is differentiation

  The process by which stem cells become specialised
• what are totipotent stem cells

  stem cells that can divide and produce any type of body cells. totipotent cells occur only for a limited time in early mammalian embryos
• define pluripotent

  Pluripotent stem cells are embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into extra-embryonic cells (the cells that make up the placenta)
• What are the uses of pluripotent cells

  They are used in research and can be used to treat human disorders

  • issues - they can continually divide to create tumours
• define multipotent stem cells

  found in adults and can differentiate into a limited number of specialised cells.
• Evaluate the use of stem cells:

  what are the benefits of using stem cells

  Benefits :

  1. Treat wide range of diseases such diabetes and paralysis
  2. organs are developed from patients own stem cells which reduce the risk of rejection
• evaluate the use of stem cells

  state the risks and issues of using stem cells 


  -stem cells cultured in the lab could become infected with a virus which could be transmitted to the patient.

  -there is a risk of cultured stem cells accumulating mutations

  -low number of stem cell donors
• evaluate the use of stem cells

  social issues


  -It is possible for embryonic stem cells to be collected before birth (amniotic fluid) or after birth (umbilical cord blood) - this is expensive and is not an option for everyone

  -a lack of peer reviewed clinical evidence of the success of stem cell treatments.

  -educating the public about what stem cells can and cannot be used for.
• producing tissue cultures from cauliflower exoplanets

  Creating clones of cauliflowers is used to demonstrate totipotency through the production of tissue culture. (Tissue culture is when cells are grown artificially, separate to the parent organism).

  A small piece of pant is cut this is called an explant, which is then grown into a new clone of the original plant.

  This technique is used to reproduce endangered species of plants.
• Method for producing tissue cultures from cauliflower explants

  Method:

  1. Wipe all surfaces with disinfectant and sterilised apparatus ( ensure no fungi contamination)
  2. break of a small floret of cauliflower from the plant then using a scalpel cut a thin section of floret
  3. sterilise explant
  4. add explanation to a container of agar growth medium (contains all the nutrients that the plant needs for growth and also ensures no contamination)
  5. Leave the container holding the agar growth medium and explanation on a sunny windowsill for 3 weeks.
• what are the results to producing cultures from cauliflower explants?

  the results of this experiment is to grow a cauliflower clone from an explant.

  this shows that the cells in the explant have the capability to produce all the different cell types that make up the full cauliflower plant. Therefore they are totipotent.
• What is RNA analysis ?

  RNA analysis looks at gene expression

  when a cell expresses a gene, RNA is produced by transcription.

  RNA present in a cell can be analysed and can be matched to the RNA present in a cell to specific genes and work out which genes are being expressed in that specific cell.