20.2 Stem cells and totipotency Flashcards
define totipotency
Having the ability to differentiate into all cell types
where are totipotent cells often found?
Early embryo stages (zygote)
why do stem cells self-renew and differentiate?
self-renewal maintains the stem cell pool
differentiation replaces dead or damaged cells throughout your life e.g creates muscle or nerve cells etc..
differentiated cells produce different proteins
list the types of stem cells
embryonic adult umbilical placental induced pluripotent (iPS) stem cells
where do we find embryonic stem cells?
blastocyst
the cells inside, the inner cell mass
What is the outer layer of a blastocyst called?
trophectoderm
what is the process of collecting embryonic stem cells for use?
remove from blastocyst
culture in a lab to grow more cells (in a fluid with nutrients)
differentiate cells into the specialised cell type required
what potency to embryonic stem cells have?
early embryo stages are totipotent
later stages are pluripotent
where do we find adult stem cells?
surface of the eye brain skin breast testicles muscles bone marrow intestines (gut)
what potency do adult stem cells have?
multi-potent
what potency do umbilical cord blood stem cells have?
multi-potent
where can we find placental stem cells
found in the placenta
what potency do placental stem cells have?
multi-potent
what types of cells can we differentiate adult stem cells into?
only specialised types of blood cell
red blood cells, white blood cells, platelets
how do we create iPS cells?
collect a cell from the body
genetically reprogram, add certain genes to the cell
cell behaves like an embryonic stem cell and can now be differentiated
what is an advantage of iPS cells?
no need for embryos
define potency
a measure of how many types of specialised cell a stem cell can make
define pluripotent
can make almost all types of specialised cells in the body
define multipotent
can make multiple types of specialised cells, but not all types. e.g tissue stem cells
define unipotent
can make one type of cell, derived from multipotent stem cells
what are stem cells?
a stem cells is a cell that is able to replicate itself while maintaining an undifferentiated state, and is then able to differentiate into mature cell types
generally, where can adult stem cells be found?
within most organs, where they replace dead or damaged cells
where can we obtain stem cells?
spare embryos created during IVF : those that aren’t implanted can have stem cells removed from the inner blastocyst.
umbilical cord blood
adult stem cells obtained from several places, come in small quantities and are hard to harvest but are used to treat many cancers
how are we currently using stem cells in research?
used in research about creating replacement human organs
therapeutic cloning
describe the process of therapeutic cloning
the nucleus of an ovum is removed and replaced with the nucleus of a cell from the patient
the cell is then administered a small electric shock to start it dividing.
once it reaches the blastocyst stage, the stem cells could be removed and cultured to create genetically identical tissues for the patient
this research has been allowed by the government, but all embryos must be destroyed after 14 days to avoid human cloning.
who would benefit from stem cell research
it could help people suffering from diseases caused by faulty cells
