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Biology revision Notes:
Cell Membrane- Holds the cell together and controls what enters/ leaves the cell
Nucleus- Controls all cell activity. Contains chromosomes and DNA
Cytoplasm- All cell activity takes place e.g. respiration
Chloroplasts- Contains chlorophyll which absorbs light energy for photosynthesis
Cellulose Cell Wall- Gives structural support, converted from glucose
Large Vacuole- Contains water and dissolves substances- cell sap
Undifferentiated, unspecialized cells with the potential to become any cell in the body; all cells in any
organism have originated from stem cells.
Adults also have stem cells, but only in certain places, such as bone marrow, these can only turn into
certain cells, not any one.
During mitosis, one cell will remain a stem cell, while one will vary slightly- the first step/ `choice' to
specializing. A series of choices must be made to get from stem cells in a zygote to an embryo.
Lots of plants don't lose the ability to specialize their cells.
Scientists are experimenting with stem cells to try and cure diseases and for transplants etc.
However, there are many moral issues, such as;
Human embryos must be destroyed- some people argue this is killing
Campaigners feel that scientists should concentrate on finding a cure.
Stem cell research is banned in many countries, but legal in the UK if guidelines are followed.