1. ** Cell sizes.**
To appreciate the differences in cell size, consider the following specific
examples.

(A)
Calculate the approximate volume of each of these three cell types in cubic
micrometers. (Recall that V = pr^{2}h
for a cylinder and that V = 4pr^{3}/3
for a sphere.)

(B) Approximately how many bacterial cells would fit in the internal volume of a human liver cell?

(C) Approximately how many liver cells would fit inside a palisade cell?

2. To get some feeling for the differences in size of various cellular structures, it is useful to compare the structures on a macroscopic scale. Listed below is a variety of structures, with their approximate dimensions. To compare their dimensions on a macroscopic scale, assume that each structure has been magnified a million-fold, using a scale such that 1 nm is represented by 1 mm. On this scale, a prokaryotic ribosome has a diameter of 25 mm, and is therefore the size of a large marble. Convert each of the other dimensions to this macroscopic scale, and suggest a physical object that has approximately the same dimensions.

1. Eukaryotic ribosome (Where proteins are made): 30 nm

2. Mitochondrion (Where chemical energy is released): 1 x 2 µm

3. Chloroplast (Which traps light energy): 2 x 8 µm

4. Nucleus (Control center of the cell): 6 µm in diameter

5. Liver cell: 20 µm in diameter

6. Chicken egg: 4 x 6 cm

7. Human being: 1.8 m tall

3. On the same macroscopic scale as in question 2, what would be the dimensions of the following?

(A) a typical cell membrane: 8 nm wide

(B) the thickness of Glad wrap: 10 µm

4. What would be the
dimensions *E. coli* and the palisade cell in question 1, if they were
placed on the same macroscopic scale as the cell structures in question 2 (i.e.,
if they were magnified a million-fold)?

5. How many cell membranes would have to be aligned side by side before the structure could be seen with the light microscope? How many with the electron microscope? (Assume a typical membrane to be about 8 nm wide.) (The limit of resolution for a light microscope is 200 nm and for an electron microscope 0.1-0.2 nm.)

Source: http://www.esb.utexas.edu/anneke/bio211/Handouts/cellexercise.htm