Biology Reference
In-Depth Information
Every aspect of membrane structural studies involves parameters that are very small and
very fast. As a result a variety of highly specialized and esoteric biophysical methodologies
must be employed, often simultaneously. It is the nature of the highly sophisticated techniques
used to investigate membrane structure that unfortunately forms an almost insurmountable
impediment between physical and biological approaches to membrane studies. This chapter
will investigate several fundamental membrane properties using specific examples taken
from the research literature. Emphasis will be placed on how the technique was employed to
address a particular question. It is not the objective of this chapter, or this topic, to discuss the
intricate details of each technique, but rather to understand what questions the technique can
address. In other words, the emphasis will be placed on application and not detailed
methodology.
A. SIZE AND TIME DOMAINS
Generally parameters of interest to the study of biological membranes will range in size from
microns (10
6
m) to Angstroms (
˚
,10
10
m) and in time from milliseconds (10
3
sec) to
.0001
x-ray
gamma
NaCl
amino acids
.001
MEMBRANE
.01
ultraviolet
.1
visible
1
10
infrared
erythrocyte
100
human ovum
1000
radiowaves
FIGURE 9.1
The electromagnetic spectrum and the size of various important biological components. Note the
average thickness of a biological membrane is a little less than 10 nm or 100
˚
.