LiroxtronIV (LiroxtronIV)-
describe unique features of stem cells
remain undy/dxed, unspecialised for long time; lacks tissues to perform specialised fns >
dy/dx unlimited no. of times, self-renewal via mitosis; allows for growth, senescence prevented via high telomerase activity; divide symmetrically(2x SC), asymmetrically(1x SC, 1 progenitor cell) >
dy/dx into specialised cell types when receiving internal, external signals; specialised cell expresses subset of genome
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describe features of totipotent stem cell, e.g. zygotic stem cell
dy/dx into any cell type within organism, including extra-embryonic tissues(make up structures supporting embryo, e.g. placenta)
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describe features of pluripotent stem cell, e.g. embryonic stem cell
dy/dx into any cell type within organism, except extra-embryonic tissues, e.g. placenta >
occurs due to differential switching of genes in genome
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describe features of multipotent stem cells, e.g. blood stem cell
dy/dx into limited but related range of cell types/tissues in organism
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describe role of embryonic stem cell
inner cell mass of blastocyst dy/dx into cells of 3 germ layers(endoderm,mesoderm,ectoderm) forming specialised cell types(organs) & eventually adult organism
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describe role of blood stem cell
dy/dx into types of RBC/WBC to maintain tissues surrounding blood by replacing worn-out/damaged RBC/WBC >
dy/dx into Myeloid PSCs >
further dy/dx into cells involved in innate immunity(macrophage, neutrophil, RBC, platelet) OR
dy/dx into Lymphoid PSCs >
further dy/dx into cells involved in adaptive immunity(B, T cell)
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discuss ethical implications of applying stem cells to research & medical applications
to obtain ESCs, must destroy embryos, poses moral dilemma of saving a human life over another >
creation of embryos is controversial as used as spare parts in research to benefit others >
embryo donor risks ↓ future reproductive success, may suffer OHSS & even death due to invasive nature of oocyte retrieval >
oocyte donors from 3rd world countries risk exploitation >
infringes on cultural/religious beliefs >
donors may face invasion of privacy/unaware of risks to give consent >
usage in medical treatment may be unfair b/w diff income groups
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what are human induced Pluripotent Stem Cells(iPSCs)?
type of pluripotent SCs formed from introduction of genes coding for TFs, causing GE of genes unique to ESCs that revert adult cells to pluripotent state; similar to ESCs to dy/dx into cell types of 3 germ layers >
risks:
retrovirus w/ genes for TFs carried in viral DNA, integrated in host genome randomly; may lead to mutagenesis as excessive gene expression occurs causing tumour formation & eventually cancer
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how human induced Pluripotent Stem Cells(iPSCs) overcome ethical dilemmas of stem cell research?
research w/ human ESCs;
iPSCs prevent destruction of embryos, lightens controversial nature of creation of embryos for research purposes & its infringement on cultural/religious beliefs
SCs clinical trials;
> safe as oocyte/embryo donors < @ risk of OHSS, death, reduces necessity of exploiting donors from impoverished countries
However, doesn't overcome issues pertaining to consent & privacy nor equity of SC usage in medical applications
