B2. Cell division and Stem Cells Flashcards
Why do cells divide by mitosis?
- To allow growth
- To repair body tissues
- To replace old/dead/worn out cells
What are the 3 stages of the cell cycle?
- Interphase
- Mitosis
- Cytokinesis
What happens during interphase?
- The cell grows in size.
- DNA replicates
- Organelles replicate.
What happens during mitosis?
- The replicated chromosomes line up along the centre of the cell.
- Spindle fibres contract and the chromosomes get pulled to opposite poles.
- Nucleus divides.
What happens during cytokinesis?
- Cell membrane and cytoplasm divide.
- 2 genetically identical daughter cells are formed.
What are the products of mitosis?
2 genetically identical daughter cells
What is a stem cell?
A cell that has not yet become specialised cell.
Give 2 properties of a stem cell?
- Can replicate many times
* Has the potential to become specialised (i.e. different types of cell).
What are the 2 main types of stem cell?
- Embryonic stem cells (from embryos)
* Adult stem cells (from adult tissues)
Where are embryonic stem cells found?
Embryonic stem cells are stem cells found in embryos.
Where are adult stem cells found?
Adult stem cells are stem cells found in adult tissues (such as bone marrow, brain, muscle, liver stem cells).
Where are stem cells found in plants?
- They are found in the meristems of a plant.
* Found in root and shoot tips
What are the advantages of using embryonic stem cells to treat diseases?
- Have the potential to develop into any type of cell/tissue.
- Cells can become any cell type.
- Used to treat human diseases.
- Painless
What are the advantages of using adult stem cells to treat diseases?
- Plentiful supply
- No ethical issues (in collection) as the person can give consent.
- Safer method as it is well tried/tested.
What are the disadvantages of using embryonic stem cells to treat diseases?
- Unethical – embryos cannot give permission.
- Possible harm/death to embryo.