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Basic Biology - Organisms and cells
 All organisms consist of small cells
Typically these cells are too small to be seen by a naked
eye, but big enough for an optical microscope.
Each cell is a complex system
consisting of many different building blocks enclosed in membrane bag, see picture. There are
unicellular (consisting only of one cell) and multicellular organisms. Bacteria
and baker's yeast are examples of unicellular organisms - any one cell is able
to survive and multiply independently in appropriate environment.
There are estimated about 6x1013 cells in a human body, of about 320 different
types. For instance there are several types of skin cells, muscle cells, brain
cells (neurons), among many others.
The cell sizes may vary depending on the cell type
and circumstances. For instance, a human red blood cell is about 5 microns
(0.005 mm) in diameter, while some neurons are about 1 m long (from spinal cord
to leg). Typically the diameter of animal and plant cells are between 10 and 100
microns.
- Karyn's Genomes - contains general information about organisms whose genomes are completely sequenced. The main aim of the database is to provide a short and concise explanation as to why it is important to obtain these organisms genomic sequences
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Organisms and cells 1/4 >>> |
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