By jennifer ross wallace f marshall data of the book building a cell from its building a cell from its component parts volume 128 methods in cell biology by jennifer ross wallace f marshall hardcover details see also ebook kindle details . Over its many years of publication methods in cell biology has built up a deep library of biological methods to study model developmental organisms organelles and cell systems as well as comprehensive coverage of microscopy and other analytical approaches. 1 a cell cannot survive if it is totally isolated from its environment the cell membrane is a complex barrier separating every cell from its external environment 2 this selectively permeable membrane regulates what passes into and out of the cell 3 the cell membrane is a fluid mosaic of proteins floating in a phospholipid bilayer 4. The formula for the surface area of a sphere is 4r 2 while the formula for its volume is 4r 3 3 as the radius of a cell increases its surface area increases as the square of its radius but its volume increases as the cube of its radius much more rapidly therefore as a cell increases in size its surface area to volume ratio decreases