What are Stem Cells? Flashcards
1
Q
What is differentiation?
A
- 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.
2
Q
Production of erythrocytes and neutrophils derived from stem cells in bone marrow
A
- In bone marrow, adult stem cells divide and differentiate to replace worn out blood cells: erythrocytes (red) and neutrophils (white that fights infection).
3
Q
Production of xylem vessels and phloem sieve tubes from meristems
A
- 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.
4
Q
Sources of animal stem cells
A
- 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.
Multipotent.
5
Q
Stem cells and medicine
A
- 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.
6
Q
Ethics
A
- 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.
