2.2 Cell Size

Cellular metabolism

Cellular metabolism depends on cell size(SA/V ratio)

cellular waste must leave

dissipate thermal energy

nutrients and other resources/chemical materials must enter

at a certain size, it begins to be too difficult for a cell to regulate what comes in and what goes out of the plasma membrane

Surface area to volume ratio (SA/V ratio)

the size of a cell will dictate the function

The surface area-to-volume ratio can restrict cell size and shape. Smaller cells typically have a higher surface area-to volume ratio as well as a more efficient exchange of materials with the

environment than do larger cells.

cells need a high surface area to volume ratio to optimize the exchange of material through the plasma membrane

Surface area divided by volume is the ratio

smaller cells have higher SA/V ratios so they are best for the exchange of material through the plasma membrane

larger cells have lower SA/V ratios so they are best for long term storage,lower rate of heat exchange

more complex cellular structures (ex. membrane folds) are necessary to adequately exchange materials with the environment

Total Surface area

height x width x number of sides x number of boxes

for spherical cells, 4(pi)r²

Total Volume

height x width x length x number of boxes

for spherical cells 4/3(pi)r³