Ratio of Surface Area to Volume in Cells

Suppose you DOUBLE the length, height, and width of a cube. How many times does the OUTSIDE area of the cube increase by?

4x

Suppose you double the length, height and width of a cube. How many times does the INSIDE area of the cube increase by? Hint: count the number of little cubes inside the big cube.

8x

What is the surface area in terms of a cell

Cell membrane

What is the volume in terms of a cell

Cytoplasm

What does a cell do to make sure that it does not grow too big?

Divide

The inside area, called the volume, grows by how much?

Eight times

Cell size limitations

Exchange of materials Information crisis/ more demands on DNA Surface area to volume ratio

Information crisis

More demands on DNA

What is the name for this outside area?

Surface area (cell membrane)

Think about what you jus learned about what happens to the surface area and volume of a cue when it doubles. What will happen to the surface area and volume of a cell if it doubles?

Surface area => 4x (cell doubles) Volume => 8x (cell doubles)

X4: X8

Surface area: volume

When a cube is doubled in size what happens to the surface area?

The surface area grows by four times the size

Surface area to volume ratio

VOLUME increases FASTER than SURFACE AREA

What increases faster, volume or surface area?

Volume increased faster than surface area

Exchange of materials

Wastes out/ nutrients in

Surface Area

length x width x 6

Volume

length x width x height