Download Cell Size

Cell Size
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Why are cells so small?
Background info:
Surface area= cell membrane
Volume= contents of cell
Raw materials= oxygen, nutrients, amino
acids, etc.
• In order for cells to function they must
transport materials across their cell
membranes and carry on metabolic
reactions all the time.
• As a cell gets larger, the amount of reactions
to keep the cell alive increase. The only way
for the cell to get the raw materials needed
for these reactions is across the cell
membrane.
• As the cell gets larger, its volume increases
faster than its surface area. So as a cell grows
its surface area to volume ratio decreases.
• At some point the cell’s volume becomes too
large for its surface area to supply it with raw
materials.
• So to reduce this effect, cells divide to stay
small or change shape by creating projections
in order to increase surface area or reduce
volume.
• The best size for a cell is to have a large
surface area compared to its volume.