What are Stem Cells? Flashcards Preview

BIO - 2.1.6 Cell Division > What are Stem Cells? > Flashcards

Flashcards in What are Stem Cells? Deck (6)
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What is differentiation?

- When cells become specialised for different functions.
- Stem cells divide to become new cells which then become specialised.
- Stem cells are also able to divide to produce more undifferentiated stem cells.


Production of erythrocytes and neutrophils derived from stem cells in bone marrow

- In bone marrow, adult stem cells divide and differentiate to replace worn out blood cells: erythrocytes (red) and neutrophils (white that fights infection).


Production of xylem vessels and phloem sieve tubes from meristems

- Plants are always growing, so stem cells are needed to make new shoots and roots throughout their lives.
- In plants, stem cells are found in the meristems. In the root and stem, stem cells of the vascular cambium divide and differentiate to become xylem vessels and phloem sieve tubes.


Sources of animal stem cells

- Embryonic stem cells:
Present at a very early stage of embryo development and are totipotent.
After 7 days, a mass of cells called blastocyst forms and cells are is pluripotent state.
They remain in this state in the fetus until birth.

Tissue (adult) stem cells:
Present throughout life from birth. Found in specific areas like bone marrow.


Stem cells and medicine

- Scientists think stem cells can be used to repair damaged tissues and treat neurological disorders like Alzheimer's and Parkinson's.
- Heart disease: muscle tissue in then heart is damaged as a result of a heart attack, normally irreparably.
- Parkinson's: symptoms are caused by the death of dopamine-producing cells in the brain; transplanted stem cells may help to regenerated those cells.
- Alzheimer's: nerve cells in brain die in increasing numbers, resulting in memory loss. Stem cells can be used to regrow healthy nerve cells.



- Removal of stem cells from embryos result in destruction of embryo.
- Religious objections against this: many believe life begins at conception so destruction of embryos is murder.