Copy table into your notebook How Cell Surface

Copy table into your notebook How “Cell” Surface to Volume Ratio affects Rate of Diffusion Cell size 1 x 1 x 1 cm 2 x 2 x 2 cm 1 x 2 x 4 cm Surface area volume Surface / vol Time of diffusion (s) Xtra line needed

Cell size Limits The cell must be • large enough to hold materials it needs • small enough to be controlled by the genetic material • ***have large enough surface to volume ratio to allow for efficient exchange of materials with environment at a rate fast enough to sustain life Most cells are between 10 - 20 um Nutrients Waste

Each side 1 cm x 1 cm = 1 cm 2 / side X 6 sides Cell size 1 x 1 x 1 cm 2 x 2 x 2 cm 1 x 1 x 8 cm Surface area ∑ w*l 6 cm 2 Volume Surface / vol Time of diffusion (s)

Volume = 1 cm x 1 cm = 1 cm 3 Sfc/vol = 6: 1 Cell size 1 x 1 x 1 cm 2 x 2 x 2 cm 1 x 2 x 4 cm Surface area ∑ w*l 6 cm 2 Volume Surface / vol W*l*h 1 cm 3 6: 1 Time of diffusion (s)

Complete chart for other 2 sizes Cell size 1 x 1 x 1 cm 2 x 2 x 2 cm 1 x 2 x 4 cm Surface area ∑ w*l Volume Surface / vol 6 cm 2 1 cm 3 6: 1 24 cm 2 8 cm 3 3: 1 28 cm 2 8 cm 3 3. 5 : 1 Time of diffusion (s) W*l*h 1 cm x 2 sides = 4 cm 2 1 cm x 4 cm x 2 sides = 8 cm 2 2 cm x 4 cm x 2 sides = 16 cm 2

In general cells are rarely larger than 20 um. But not always, Can U think of a cell type that can be over a meter long? How could an organism increase its size wo decreasing efficiency?

1. Surface: volume ratio can be increased by 1. Altering cell shape: elongating ex. Microvilli, alveolar epithelium

Surface: volume ratio can be increased by • • Altering cell shape: elongating , foldsx. Microvilli, alveolar epithelium Cell ÷ creating more cells w/ same total vol. ex multicellular organism ppt 3