2.1.6 Cell Division: Stem Cells

2 features of stem cells

Self renewing; undifferentiated

Sources of stem cells

Adult; embryonic; fetal; umbilical cord; artificially convert somatic cell

Where could you find adult stem cells

Bone marrow

Where are embryonic stem cells taken from

Inner cells of early embryo

Where are foetal stem cells taken from

Miscarried/aborted foetus

Totipotent meaning

Can form any embryo cell + extra-embryonic tissues

What are extra-embryonic tissues

Tissues not part of embryo e.g. placenta

Pluripotent meaning

Can differentiate into any cell type in embryo

Multipotent meaning

Limited potency

Potency of adult stem cells

Multipotent

Potency of embryonic stem cells

Pluripotent

Where could you find totipotent stem cells

Zygote up to 16 cells

Potency of foetal stem cells

Multipotent but approaching pluripotent

Cons of harvesting stem cells from bone marrow

Risky/painful; babies conceived to provide bone marrow for sibling

Ethical considerations of fetal stem cells

Miscarried/aborted foetuses - foetuses are not killed

Cons of embryonic stem cells

Embryo destroyed, can’t give consent

Where might you get embryos from to get stem cells

Excess IVF embryos

2 types of cells that could derive from bone marrow stem cells

Erythrocytes; neutrophils

Why is it important that RBCs develop in bone marrow

RBCs have no nucleus so cant divide by mitosis

What kind of things happen while differentiating into an erythrocyte

Loss of nucleus; shape change; increased Hb production

What kind of things might happen while differentiating into a neutrophil

Increased production of hydrolytic enzymes; increased membrane flexibility

2 different outcomes that may arise from meristem stem cells

Xylem vessel; phloem sieve tube

Uses of stem cells in medicine/research

Repair of damaged tissue; treatment of neurological disorders; developmental biology research

What kind of diseases might stem cells be used to repair damaged tissue

T1 diabetes (pancreas cells); burns (skin cells)

How can stem cells help treat neurological disorders

Differentiate into nerve cells - replace dysfunctional ones

How can stem cells help with research into developmental biology

Can study embryonic stem cells developing into embryos