# The Relative Sizes of Cells

Various types of cells and cellular components are listed below. Based on the diameters of the cells and components (given in parentheses), calculate the number of each that you would expect to find in a single layer that is 0.7 mm in diameter. Assumption: each entity is spherical. Formulas: area of a circle = pi*r^2. pi=3.14

hepatocyte (d=20 micrometer)

mitochondria (d=1.5 micrometer)

actin molecule (d=3.6 nanometer)

#### Solution Preview

...= pi*r^2 = 3.14*(7/2)^2=38.5 mm^2

Next, calculate the area of a hepatocyte:

area = 3.14*(0.02mm/2)^2=0.000314mm^2

Now, calculate the number of hepatocyte areas that will fit in to one 0.7mm area:

#=total area/area of ...