15945247
Description
Mind Map by Maeesha Hussain, updated more than 1 year ago
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Created by Maeesha Hussain
about 6 years ago
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B2 Topics (AQA Biology)
- The need for mitosis New cells are produced from cells which already exist by cell division. Single
celled organisms can reproduce in this way to make new organisms, whilst in multicellular organisms
cell division leads to growth. In all cases cell division is the method of increasing the number of cells.
Chromosomes are threadlike structures found in the nucleus of most cells (remember red blood cells
have no nucleus and so these are not produced by mitosis). Chromosomes carry information in the
form of genes. Genes control the nature of the organism (e.g. what it looks like, its behaviour and all
its chemical reactions). Because it contains the chromosomes the nucleus controls all the activities of
the cell (including cell division). All the cells in the body of a particular species contain the same
number of chromosomes. Cell division, or mitosis, is the method of increasing the number of cells.
Single celled organisms can reproduce in this way to make new organisms. Multicellular o
- All animal and plant cells have a nucleus, cytoplasm and a cell membrane. Plant cells also have a cell
wall, chloroplasts and a vacuole. Different parts of the cell are adapted to perform different functions.
Humans grow at different rates at different stages in their lives. Gestation and infancy are the times
of fastest growth. Growth Plant and animal cells All animals and plants are made of cells. Animal cells
and plant cells have features in common, such as a nucleus, cytoplasm and cell membrane. Plant cells
also have a cell wall, chloroplasts and a large vacuole.
- Stem cells During the development of an embryo most of the cells become specialised. They cannot
later change to become a different type of cell. But embryos contain a special type of cell called stem
cells. These can grow into any type of cell found in the body. They are not specialised. Stem cells can
be removed from human embryos that are a few days old, for example, from unused embryos left
over from fertility treatment. Here are some of the things stem cells could be used for: • Making new
brain cells to treat people with Parkinson's disease • Rebuilding bones and cartilage • Repairing
damaged immune systems • Making replacement heart valves
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