Cell Division Flashcards
What are chromosomes ?
Chromosomes carry genetic information in a DNA molecule
What is a gene
Section of a chromosomes that contains the code for the production of a particular protein
How many pairs of chromosomes does each body cell have ?
23
What is the point of the cell cycle + mitosis
Growth and repair
Outline the cell cycle
- The cell grows its subcellular structures
- DNA synthesis - the chromosomes are now double stranded
- further growth - DNA checked for errors
Outline mitosis
DNA replicates to form two copies of each chromosome
Nuclear membrane breaks down - chromosomes line up in the centre of the cell
One set of chromosomes is pulled to each end of the cell by fibres and the nucleus divides
The cytoplasm and cell membranes divide to form two identical daughter cells
Outline mitosis
DNA replicates to form two copies of each chromosome
Nuclear membrane breaks down - chromosomes line up in the centre of the cell
One set of chromosomes is pulled to each end of the cell by fibres and the nucleus divides
The cytoplasm and cell membranes divide to form two identical daughter cells
What is a stem cell ?
cells that have not undergone differentiation - not specialised for a specific function.
Stem cells are first found in the…
Embryo. If they are removed from the embryo ( embryonic stem cells ) they can differentiate into anything
Adult stem cells are found in…
Bone marrow brain eyes blood liver skin muscle
stem cells from bone marrow can differentiate into…
Blood cells or cells of the immune system
Stem cells in plant ?
Meristems. as cells grow older they differentiate in vacuoles
Cell differentiation
zygote must divide to produce a multicellular organism. Must differentiate to fulfil specific roles
Cloning in plants ?
Cells from meristems can be cloned
Meristematic cells removed from plant and grown in tissue culture
Cells grown in a culture medium that contains agar - provide water for growing cells
Done to produce identical plants quickly and economically
This is useful to provide crop plants for large-scale cultivation that have desirable characteristics such as disease resistance.
Using human stem cells
could be used to replace cells that have been damaged or destroyed
- diabetes
- paralysis
- could be embryonic stem cells
- could be adult stem cells
When are adult stem cells used
To replace blood cells that have been destroyed by cancer treatment
blood cell cancer such as leukemia
Therapeutic cloning ?
Not rejected by patients immune system. Could produce stem cells with the same genetic make up as its patient
Technique ?
- nucleus removed from patient’s cell
- nucleus of patient transferred to donor egg cell
- nucleus from donor egg cell discarded
- cell divides and forms an embryo
- after 4/5 days - stem cells removed
- Stem cells from embryo are cultivated for therapeutic use
Clinical issues with therapeutic cloning ?
- No guaranteed success rate
- difficulty in finding stem cell donors
- Mutations of stem cells - some have behaved like cancer cells
- Cultured stem cells could be contaminated with a virus that could be transferred to the patient.
Ethical issues with therapeutic cloning ?
seen as a commodity and not as a future person
- Is it right to create embryos for therapy and destroy them in the process
social issues about therapeutic cloning
Educating the public about what stem cells can, and can’t do, is important.
