stem cells and epigenetics

• polygenic

  characteristic showing continuous variation

  caused by multiple genes at different loci
• explain how epigenetic changes affect the development of tissues in the embryo

  • dna is wrapped around histones
  • histone modification will affect binding of RNA polymerase which affects how tightly the DNA is wound
  • methylation of DNA will affect the transcription of genes and production of mRNA
  • therefore gene expression is altered
• give one difference between a tissue and an organ

  a tissue is made out of one type of cell

  an organ is made of different tissues
• describe the decisions society has to make about the use of these embryonic stem cells

  embryonic stem cells are totipotent and can be used in a wider range of therapies

  the source of embryonic stem cells has to be considered or regulated

  there is also the ethical issues as the use of embryo cells destroys viable embryos

  there is also a need for research establishments to be regulated and licensed
• describe the decisions that society has to make about the use of these embryonic stem cells

  • source of embryonic stem cells has to be considered or regulated
  • using embryo cells destroys viable embryos
  • research establishments to be regulated and licensed
• totipotent cell

  a cell that has the ability to differentiate into all cell types
• describe how cells become specialised

  cell receives chemical stimulus

  causes specific gene to be activated

  genes are transcribed to mRNA

  mRNA is translated to ribosomes to produce specific proteins

  specific proteins modify the cell or determine structure of the cell
• explain why stem cells from the heart cannot be used to grow cells to repair the cornea


  the stem cells are not totipotent, means some genes have already been activated and deactivated , therefore they will be not be able to specialise into cornea cells