Interacting with the Outside World: How We Found Out

What model was used to study cell membranes?
Much of the early research on membranes was done on red blood cells. Red blood cells have lost all their organelles. They contain only the oxygen-carrying protein, hemoglobin.

Red cells are important to learn about for several reasons:

Red cells are easy to get (from people, animal slaughter houses, etc.).
Small amounts of blood have lots of cells (1 ml has about 5,000,000,000 or 5 billion cells). So, if you want to measure a single cell you can measure a whole bunch and then divide by the total number of cells. This would give you information for each cell.

Red cells are fairly sturdy. When put in a test tube, they can be spun at high speeds to pack all the cells tightly together at the bottom of the tube.

The round shape makes it easy to use equations to estimate diameter and surface area.

Many of our ideas about membranes came from the study of red blood cells.
(click on image for larger view)

Red Blood Cells