Cell Size Limits


Cell Size

Surface area : Volume

Ch 8.2 pg 201

Cell Size Limits

Are whale cells the same size as sea stars cells?


Cell Size Limitations

Getting things into cell at an efficient rate

– Nutrients

– Water

– Oxygen

Removing things from the cell quickly

– wastes

DNA limits cell size

– If cell is too big then DNA cannot make enough proteins to support the cell

What limits the size of cells?

Surface Area to Volume Ratio - How much space is on the outside (cell membrane) compared to the space on the inside of the cell.

As the surface area of something increases, it’s volume increases faster

Surface area = L x W x # of sides (cm 2 ) the surface of an object. The outside covering of a cell. (cell membrane)

Volume = L x W x H (cm 3 ) The space inside the cell

A small object has a high surface area to volume ratio ex: 6/1

A large object has a small surface area to volume ratio ex: 24/8

Large Cell

It takes more time for the nutrients to reach the center of this cell

Smaller cell

It takes less time for the same nutrients to reach the center of this cell



As a cell gets larger which increases at a faster rate, the surface area or the volume?



If a cell were larger, would it’s interior structures be closer or further from the cell membrane?



What problems might occur if cells were too large?

Not enough nutrients in fast enough


As cell size increases, the surface area to volume ratio Decreases (small surface area to volume ratio) , which can lead to death of a cell.

Having a large surface area to volume ratio is important to the functioning of cells since it gets materials, nutrients, O 2 , & wastes into & out of it faster.

Cells divide before they get too big!