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The Smallest Vessel of Life

Cells are the smallest unit that can carry out life processes.  The role that a cell plays in life depends on several factors.  One is the type of cell it is.  If it is a bacteria, it has only itself to depend upon because bacteria are single celled organisms.  This type of cell is a unicellular (single celled) organism.  Another type of cell belongs to larger organisms.  These types of organisms
are called multicellular (many celled) organisms.
The cells that make up these organisms have
different sizes.  What determines how large
a cell can get?  Is size important to cells?  Of
course size is very important to cells.  Because
cells have to get energy, the components that
make up the inside of the cells, the organelles
must lie close to the cell membrane.  The
membrane is the "gate" that regulates what gets
in and what leaves the cell.  Nutrients have to
pass through the membrane.  Because the
organelles of the cell have to use the nutrients and there is no way for the nutrients to be distributed within the cell, the organelles must lie close to the cell membrane.  The things that limit cell size are surface to volume ratio and how close the organelles are to the membrane. 


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