Cell division B2 biology aqa

cell division
1. the cell cycle
  1. call division is necessary for the grown and development of new cells
    1. cells grown and replicate their DNA so theres two sets
      1. chromosomes are pulled to opposite sides of cell
        cell membrane and cytoplasm divide creating two cells
2. there are 23 pairs of chromosomes in human cells
growth and differentiation
1. multicellular organisms do not contain one type of cell, over time the each differentiate
2. in early development unspecialised cells are called stem cells
3. plant cells can differentiate throughout their life, actively dividing ones are called meristems
4. difficult to clone because once they have differentiated they are like that until they die
stem cells
1. found in human embryo and adult bone marrow
2. egg and sperm fuse to form a zygote, it divides to form an embryo
3. adult stem cells can differentiate into other cells ie. blood cells
4. they can be used to cure conditions such as:
  1. paralysis (new nerve cells)
    1. diabetes (new cells that will accept/produce insulin)
stem cell dilemmas
1. some people believe its a violation of the embryos rights
2. we should not interfere in the natural process of reproduction
3. its difficult to 'persuade' the cells to differentiate
4. because they divide rapidly theres s concern that the could cause cancer
5. cells from same person have less chance of being rejected

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	Creado por Millie Jones hace más de 5 años