Topic 2.3 - Cell Size

Cell size

Cellular metabolism depends on cell size. 

A cell’s membrane must let cellular waste leave and get rid of thermal energy, while still letting nutrients and other resources in. 

• Getting too large can hinder these operations.

Size dictates function.

A cell needs a high surface area-to-volume ratio to optimize the exchange in the membrane. 

• To calculate surface area-volume ratio, find the surface area and the volume and divide them over each other. 
  • Volume increases faster than surface area.

Smaller cells tend to be more efficient because they have more waste to get rid of, and the volume increases faster. 

• They are optimized for the exchange of materials. 

Cell folds to increase surface area. 

• EG: Root hairs help to increase surface area
• EG: Villi and microvilli (organelles) are present on some cells to increase the surface area by a lot, such as on small intestines, which help to increase efficiency in absorption of materials. 

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