body cells divide in a series of stages called the cell cycle.
during the cell cycle the genetic material is doubled. it then divides into two identical nuclei in a process called mitosis.
before a cell can divide it needs to grow, replicate the DNA to form two copies of each chromosome and increase the number of sub-cellular structures.
in mitosis one set of chromosomes is pulle to each end of the cell and then the nucleus divides.
finally the cytoplasm and cell membranes divide and form two identical cells.
mitotic cell division is important for the growth, repair and development of multicellular organisms.
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B2.2: Growth and Differentiation
in plant cells, mitosis takes place throughout life in the meristems found in the shoot and root tips.
many types of plant cells retain the ability to differentiate throughout life.
most types of animal cells differentiate at an early stage of development.
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B2.3: Stem Cells
embryonic stem cells are from human embryos and adult stem cells are from adult bone marrow.
they can be cloned and made to differentiate into different types of cells.
treatment with stem cells may be able to help conditions such as paralysis and diabetes.
stem cells from plant meristems are used to produce new plant closed quickly and economically for research, horticulture and agriculture.
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B2.4: Stem Cell Dilemmas
treatment with stem cells, from embryos or adult cell cloning may be able to help with conditions such as diabetes.
in 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.
the use of stem cells has potential risks and some people have religious or ethical objections.
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