B2 Cell Divison Flashcards
In body cells, chromosomes are found in…
Pairs
Stage 1 of the cell cycle
Replication of DNA to form two copies of each chromosome and synthesis of new sub-cellular structures
Stage 2 of the cell cycle
Mitosis-one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides
Stage 3 of the cell cycle
Cytoplasm and the cell membrane also divide to form two identical daughter cells
Mitotic division is important for the…
Growth, repair and development of multicelluler organisms
Most specialised cells can divide by mitosis but…
They can only form the same sort of cell
Some differentiated cells such as red blood cells and skin cells cannot…
Divide at all and so adult stem cells replace dead or damage cells
Nerve cells cannot…
Divide once they have differentiated and they are not usually replaced by stem cells
In animals, many types of cells become specialised…
Very early in life
In contrast to animal cells, most plant cells are able to differentiate…
All their lives
Meristems
Active regions of the stems and roots where undifferentiated cells are formed and where mitosis takes place almost continuously
Many types of plant cells retain the ability to differentiate…
Throughout life
Zygote
A single new cell formed when an egg and sperm cell fuse
Embryonic stem cells
Undifferentiated cells that can differentiate into any type of cell
Adult stem cells
Undifferentiated cell of an organism which can give rise to many more cells of the same type
Treatment with stem cells may be able to help conditions such as…
Paralysis and diabetes
How are stem cells from plant meristems used?
To produce new plant clones quickly and economically for research, horticulture, and agriculture
Problems with stem cells
Embryonic stem cells divide and grow rapidly and there is some concern that they might cause cancer. There is a risk of adult stem cells being infected with viruses. Stem cells from another adult may trigger an immune response in the patient
Ethics of embryonic stem cells
Some question the use of potential humans as a source of cells even to cure others. Some people feel it is a violation of human rights as the embryo cannot give permission. Religious beliefs mean they cannot interfere with human reproduction
Theraputic cloning
An embryo is produced with the same genes as the patient so the stem cells produced are not rejected and may be used for medical treatment
