Studied by 1 personwhat is a stem cell?
cell types which can divide and renew; be eventually differentiated into different cell lineages
can stem cells self-renew to recreate functional tissues?
yes
can stem cells be used to replace cells/tissues that have been damaged or lost to disease?
yes
what are the two properties of stem cells
they can make copies of themselves and become two or more other cell types
which of these is not a property of stem cells?
A. stem cells can make copies of themselves
B. stem cells can become two or more other cell types
C. stem cells are found only in the embryo
C. stem cells are only found in the embryo
what differentiates different stem cell types?
how many other cell types they can become
what are the three stem cell types?
totipotent, multipotent, and pluripotent
totipotent cells
form all cell types in the body, including extra embryonic or placental cells (embryonic cells within the first couple of cell divisions after fertilization are the only cells that are totipotent)
pluripotent cells
can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent (post 8 cell divisions)
multipotent cells
can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells are cord blood stem cells are considered multipotent
up to the 8-cell stage, embryonic cells are what cell type
totipotent (can produce placenta and all cells of organism)
after the 8-cell stage, embryonic cells are considered
pluripotent (can produce all cells of adult organism but NOT the placenta)
cells of the inner cell mass are of what cell type
pluripotent (give rise to the fetus)
what is the name of a type of blastula cell (pluripotent), aka very early stage embryo
blastocyst
embryonic stem cells are what type of stem cell?
pluripotent
what are the three germ layers that make up the adult body?
mesoderm, ectoderm, endoderm
the inner cell mass isolated from the blastocyst (gives rise to the fetus) can differentiate into which germ layers?
mesoderm, endoderm, and ectoderm
external germ layer
ectoderm
middle germ layer
mesoderm
internal germ layer
endoderm
when do cells lose their pluripotency?
gastrulation stage
what is cell movements lead to the formation of 3 layers of cells called germ layers
gastrulation
when cells have reached the gastrula stage, can they be used for therapeutics?
no; they’ve received their specific mRNAs and can’t differentiate into anything different
what is the biggest source of embryonic stem cells?
in vitro fertilization (IVF) therapy
why can’t embryonic stem cells be used for research?
ethical issues and legal issues
what are benefits of human embryonic stem cells?
pluripotent cells provide max possibilities for developing therapeutics and understanding differentiation/development
what are drawbacks of using human embryonic stem cells?
unethical depending on beliefs, some states have banned human embryo research, and they can be difficult to grow and manipulate
why are adult stem cells necessary for the body?
some organs need a constant supply of cells (ex: GI tract, hair cells, etc.)
characteristics of adult stem cells
capable of self-renewal and differentiation, undifferentiated cells can continue dividing indefinitely but produce some daughter cells that undergo terminal differentiation, multipoint stem cells, can be unipotent stem cells (give rise to cells that differentiate into a single cell type)
benefits of using human adult stem cells
less ethical dilemmas, easier to differentiate a cell with limited potential (than one w unlimited), no risk of immune rejection
drawbacks of using adult stem cells
limited differentiation (multipotent vs. pluripotent), difficult to isolate, difficult to culture (ex: HSC can’t be cultured in vitro w/out losing SC character bc of differentiation)
which of these statements is correct?
A. embryonic SC are isolated from cells in blastocyst at a very early stage embryo
B. inner mass cells become fetus while trophoblast becomes placenta
C. inner cell mass of blastocyst are multipotent
D. early stage embryo up to 8-cell stage is totipotent and can produce placenta and all cells of organism
A. B. and D.
What are the drawbacks of adult human stem cells? (select all)
A. multipotent
B. often difficult to isolate
C. illegal in some states
D. ethical issues - depending on someone’s beliefs
E. difficult to culture
A. B. and E.
what is nuclear transfer?
inserting the nucleus of an already differentiated adult cell (ex: skin cell into donated egg that had its’ nucleus removed)
after nuclear transfer, what cell type is the cell stimulated to form?
blastocyst (ESC can be derived from here)
what famous experiment used nuclear transfer?
cloning of Dolly the sheep
what is transdifferentiation
conversion of one cell type to another
what is determination?
cell undergoes a self-perpetuating change of internal character, that distinguishes its progeny from other cells and commits it to a specialized course of development
what provided evidence that terminally differentiated chromatin from an adult can be reprogrammed to allow transdifferentiation?
Somatic Cell Nuclear Transfer (specific type of NT)
what are iPSCs?
a type of pluripotent stem cells that are particularly amenable to therapeutic uses
important features of iPSCs
can be made from any living person so they can be immune-matched (or DNA-matched) to any patient (reduces need for immune suppression)
can be made from any person, and used to model any disease
term for immune matched cells
“autologous”
term for unmatched immune cells
“allogenic”
how are iPSCs made?
skin cells (fibroblasts) or blood cells from adults are converted via reprogramming
how is the reprogramming process mediated?
via viruses or mRNAs that produce proteins involved in pluripotency
AND
with Yamanaka Factors
Rank these from highest to lowest degrees of SC potency
Multipotent, Pluripotent, Totipotent, Unipotent
Totipotent, Pluripotent, Multipotent, Unipotent
________ is the conversion of one cell type to another
transdifferentiation
which of these statements are correct?
A. hematopoietic SC are found in the peripheral blood and bone marrow
B. ES cells are pluripotent cells derived from inner mass of blastocyst
C. skin cells (fibroblasts) or blood cells from adults are converted into iPSCs via transdifferentiation
D. Yamanaka factors are a group of TFs that play a vital role in the creation of iPSCs
E. Electric pulses cause the donor cell to split into equal halves during the process of somatic cell nuclear transfer
A. B. and D.
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