- Created by: maddieecarr
- Created on: 26-11-19 14:41
B2.1: Cell Division
- in body cells, chromosomes are found in pairs.
- 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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