B2 pages 26-35 cell division Flashcards
what is differentiation
the process where cells become specialised for a particular function
what is interphase in the cell cycle
cell grows in size
-DNA replicates and organelles replicate.
what is mitosis in the cell cycle
replicated chromosomes line up along the centre of the cell -Spindle fibres contract and the chromosomes get pulled to opposite poles
-Nucleus divides
what is Cytokinesis in the cell cycle
cell membrane and cytoplasm divide
- 2 new identical daughter cells are formed.
What is a stem cell
A cell that has not yet become specialised cell.
what can a stem cell do
Can replicate many times
Has the potential to become specialised (i.e. different types of cell)
name 3 types of stem cells
Embryonic stem cells
Adult stem cells
Meristems in plants
what are Embryonic stem cells
are stem cells found in embryos are known as embryonic stem cells and can differentiate into almost every cell type under the right conditions in a lab.
what are adult stem cells
are stem cells found in adult tissues (such as bone marrow, brain, muscle, liver stem cells). They can differentiate only into cells from the type of tissue where they are found. e.g. liver stem cells can only become liver cells.
where are meristems in plants found
Found in root and shoot tips
what can meristems in plants do
They can differentiate into any type of plant, and have this ability throughout the life of the plant
what can meristems be used to make
They can be used to make clones of the plant- this may be necessary if the parent plant has
certain desirable features (such as disease resistance), for research or to save a rare plant from extinction.
advantages of embryonic stem cells (unspecialised cells from embryos)
- Have the potential to develop into any type of cell/tissue.
- Cells can become any cell type.
- Used to treat human diseases.
- Painless
disadvantages of Embryonic stem cells
unspecialised cells from embryos
- Unethical embryos cannot give permission.
- Possible harm/death to embryo.
advantages of Adult stem cells
unspecialised cells from adult tissues e.g. bone marrow
- Plentiful supply
- No ethical issues (in
collection) as the person
can give consent. - Safer method as it is well
tried/tested
disadvantages Adult stem cells
unspecialised cells from adult tissues e.g. bone marrow
- Painful to extract
- Fewer diseases can be treated
- Can only form the type of cells
as the tissue they were taken
from. - Possibility of infection during
extraction of stem cells.
what have stem cells been used to treat
Stem cells have been used to treat conditions such as:
• Paralysis
• Diabetes
• Eyesight in the blind
what does therapeutic cloning involve
Therapeutic cloning involves an embryo being produced with the same genes as the patient.
what is therapeutic cloning used for
The embro prodced cold hen be haresed o obain he embronic sem cells
These cold be gron ino an cells he paien needed sch as ne isses or organs
what is an advantage of therapeutic cloning
The adanage is ha he old no be rejeced as he old hae he exact same genetic make-up as the individual.
describe the stages in therapeutic cloning
nucleus from skin cell
human egg with nucleus removed
inject skin cell nuclei into enucleated egg
cloned embryo created
stem cells extracted
stem cells can form any cell type for possible organ repair and transplant
