L26: Cell differentiation, stem cells, modern medicine

• cells become more specialised and less flexible during development
• label 1

  A) 8-cell stage

  B) cell polarisation

  C) compaction

  D) inner, apolar cells cut off

  E) ICM

  F) Trophectoderm

  G) blastocyst

  
• an embryo begins as a small number of naive, totipotent cells.
• embryonic stem cells can give rise to all cell types except trophectoderm
• a cells fate is progressively limited until it becomes terminally differentiated and can only give rise to the same type of cell
• embryonic cells are not differentiated

  A) nucleus

  B) embryonic precurser cell

  C) myoD

  D) DNA

  E) OFF

  F) OFF

  G) any type

  H) differentiated cell

  I) muscle specific genes

  J) transcribed

  
• differentiated siganls from other cells lead to activation of a master regulatory gene called myoD. the cell makes a myoD protein, the translator that acts as an activator is called a myoblast
• FIRST THEIR FATE BECOMES DETERMINED

  A) myoblast (determined)

  B) mRNA

  C) OFF

  D) MyoD protein

  E) transscription factor

  F) muscle cell

  G) transcription factors

  H) activated

  
• determination from myoblast, the embryonic cell is irreversibly committed to a particular cell type
• Finally the cell is terminally differentiated, playing a functional role in the organism

  A) part of a muscle fibre

  B) fully differentiated

  C) mRNA

  D) MyoD

  E) mRNA

  F) transcription factor

  G) myosin

  H) muscle proteins

  I) blocking proteins

  
• differentiated cells contain all the DNA required to build an entire new organism
• embryonic stem cells are harvested from the inner cell mass of mammalian blastocyst embryos
• human embryonic stem cells are pluripotent: they can develop into any of the 200 or so types of cell in our bodies, given the right conditions
• the cells are derived from these ESCs are genetically identical to embryo donor
• induced pluripotent stem (iPS) cells are made by reprogramming adult skin cells. they can be made by anyone and are genetically identical to the source skin cells.
• ips are pluripotent, they can generate any cell type
• Adult stem cells can divide without limit.
• adult stem cells are undifferentiated, multipotent cells
• adult stem cells can divide to give rise to both stem cells and cells, which will go on to differentiate into one or more types of functional tissue cells
• umbilical cord cells, stem cells from blood isolated from umbilical cord of newborn babies are kept frozen (banked)
• umbilical cord stem cells are multipotent, as they are immature blood stem cells, they are less restricted than blood stem cells from adults.
• umbilical cord stem calls can be used to treat leukaemias and many other blood diseases
• label 2:

  A) renewal tissues

  B) tissues

  C) blood

  D) skin

  E) constant renewing

  F) haematopoietic

  G) bone marrow

  H) transplants

  I) stem cell

  J) cell division

  K) stem cell

  L) progenitor cell

  M) fat

  N) bone

  O) white blood

  
• A fertilised egg is totipotent, able to give rise to all cell types via cell division
• embryonic stem cells are pluripotent and can become all/any cells of the body
• adult stem cells such as bone marrow cells usually only give rise to one or a few cell types: multipotent
• different culture conditions are used to persuade stem cells to develop into different kinds of differentiated cells
• integrative gene therapy is based on the idea that it may be possible to alter the genetic code of an individuals cells. it is proposed as a way of corercting single gene disorders
• a normal allele could be inserted into cells of the affected tissue
• a virus can deliver material into human cells
• label 3:

  A) cloned gene

  B) insert RNA

  C) normal allele

  D) retrovirus

  E) viral vector

  F) viral RNA

  G) Viral capsid

  H) infect bone marrow cells

  I) removed

  J) patient

  K) bone marrow cell

  L) chromosome

  
• regenerative medicine is based on the idea that pluripotent stem cells can be used to repair or replace damaged organs or tissues
• pluripotent stem cells can be made from skin cells or blood cells from a patient or matched donors or from embryos
• these stem cells can be encouraged to differentiate into specific cell types such as neurons or retinal cells
• the differentiated cells can be transplanted into patients