B2 Flashcards
How is cell division in mitosis important in fully grown/mature animals
Because it helps repair tissue/replace cells
What do chromosomes do?
Carry the genes for making all the new cells, tissues and organs in an organism
Gene
A small packet of DNA that controls a characteristic in an organism
How many chromosomes are in the nucleus of your body cells
46, arranged in 23 pairs
Areas with continued growth/replacement of cells
(due to mitosis)
Hair follicles
Skin
Blood
Lining of digestive system
Is mitosis quicker in a child or adult?
In a child
How long is the cell cycle?
Depends on the cells involved and the stage of life of the organism. The cell cycle is a short as a baby develops new cells before it’s born, increases during childhood but slows down when an adult goes through puberty.
Growth
A permanent increase in size as a result of cell division/enlargement
Adult stem cells
Replaces dead or damaged differentiated cells that can’t divide e.g. red blood cells and skin cells
Cloning
Producing identical offspring
Animal cloning
It’s difficult to clone animals as they differentiate early in their embryo development.
Embryonic stem cells
Form as the egg and sperm cell fuse to form a zygote and
this cell divides to become a hollow ball of cells - the inner cells here are the embryonic stem cells. These cells can differentiate into any type of cell needed in the body.
Adult stem cell
Undifferentiated cell of an organism that can give rise to many more cells of the same type
Problems with embryonic stem cells
Ethical concerns
Could cause cancer
Slow/difficult progress
Problems with adult stem cells
Could be infected with a virus
Could trigger an immune response
Patient may need some immunosuppressant drugs
Therapeutic cloning
Using cells from an adult to produce a cloned early embryo of themselves. This provides a source of embryonic stem cells.
Advantages of therapeutic cloning
The embryonic stem cells produced are used for medical treatments
New organs made from the original donor in a medical treatment won’t be rejected by body as they’ve been made from the body’s own cells and have the same genes
Where are plant stem cells
Meristems
Gene
A section of DNA that controls the development of specific characteristics in an organism.
Zygote
The single new cell formed by the fusion of gametes in sexual reproduction
How can stem cells treat diabetes?
Stem cells can turn into the special insulin-producing cells in the pancreas that are so important for controlling blood sugar.
Disadvantages of therapeutic cloning
Poor success rate
Shortage of donors/eggs
One economic use of plant stem cells
To produce large numbers of identical plants
1 nanogram
-9
10 g
