B2: Cell Division Flashcards
What are embroyonic stem cells?
The egg and sperm cell form a zygote- it divides and becomes a hollow ball of cells-embryo
The inner ball of these cells are called the embryonic stem cells.
Why do cells divide my mitosis?
- to allow growth
- to repair bpdy tissues
- to replace old/dead/worn out cells
What are the stages of the cell cycle?
- interphase
- mitosis
- cytokinesis
What happens during the 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
- the spindle fibres contract and the chromosomes get pulled to opposite poles
- the nucleus divides
What happens during cytokinesis?
- cell membrane and cytoplasm divide
- 2 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
What ate the properties of a stem cell (2 answers)?
- can replicate many times
- has the potential to become specialised (any type of cell)
Where are embryonic stem cells found?
Embryos
Where are adult stem cells found?
Adult tissues such as bone marrow, brain, 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 disease?(4 answers)
- potential to develop into any cell/tissue
- cells can become any type
- used to treat human diseases
- painless
What are the advantages of using adult stem cells to treat disease(3 answers)?
- plentiful supply
- no ethical issues
- safer method(well tried/tested)
What are the disadvantages of using embryonic stemm cells to treat disease?(2 answers)
- unethical (no consent)
- possible harm/ death to embryo
What are the disadvantages of using adult stem cells to treat disease?( 4 answers)?
- painful to extract
- fewer diseases can be treated
- -can only form the type of cells from the tissue they were taken from
- infection risk during stem cell extraction
What has stem cells been used to treat?
- paralysis
- Diabetes
- eyesight in the blind
What is therapeutic cloning?
It involves an embryo being produced with the same genes as the patient
What are the stages of theraputic cloning (6 steps)?
- The nucleus from a human skin cell (doner) is removed and kept
- Nucleus from a human egg cell is removed and discarded
- Skin cell nucleus is inserted into the empty egg cell
- Egg cell is given an electric shock to stop it from dividing
- This develops into a embryo
- The cells from this embryo are used to treat diseases
Why is therapeutic cloning used?
So the stem cells produced are not rejected and may be used for medical treatment
Stages of an evaluate Qs
Comparison 1
Comparison 2
Comparison 3(use data provided)
(Remeber to use works like whereas)
Balanced conclusion
What is differentiation?
The process where a cell changes to become specialised for its job
What is a ‘specialised cell’?
A cell that has a specific structure and performs a specific function
When do animal cells lose the ability to differentiate?
They lose the ability to dofferentiate after they become specialised
What type of cells can adult stem cells differentiate into?
They can only differenciate into cells from the type of tissue where they are found (liver stem cells can only beocme liver cells)
What type of cells can embryonic cells differenciate into?
Almost every cell under the right conditions in a lab
When do plant cells lose the ability to differentiate?
Stem cells (found in meristems) can differentiate into any type of plant cell throughout the plants entire life
The stem cells in meristems can be used to_________
Make clones of the mature parent plant quickly and economically.
Why are plant clones good?(3 answers)
It gives is a away of producing large numbers of rare plants reliably and safely
- we could save some plants from extinction by doing this
- it gives us a good source of reasearch
- it can get a large amount of crops resistant to disease.
