Biology Reference
In-Depth Information
FIGURE 1.4
Christian de Duve (1917
e
).
Courtesy of Christian de Duve Institute of Cellular Pathology
[24]
.
the matrix, houses most of the enzymes involved in the Krebs Cycle (terminal steps in sugar
oxidation) and
-oxidation (fatty acid oxidation)
[21]
. The inner mitochondrial membrane is
surrounded by a second membrane, the outer mitochondrial membrane, which is very
different and far less dynamic than the inner membrane. Mitochondria have been defined
as 'semi-autonomous, self-replicating organelles', meaning they grow and replicate indepen-
dently of the cell in which they are housed. This is a vestige left over from their origin as
freely living prokaryotes that took up refuge inside larger prokaryotes about 1.5 billion years
ago. This concept, known as Endosymbiont Theory
[22,23]
, was originally ridiculed, but is
now generally accepted. Mitochondria contain their own, albeit small, genome and code
for a handful of mitochondrial membrane-protein components.
b
D. SIZE OF DOMAINS
Since membrane studies span a wide range of size and time domains, a variety of often
esoteric instrumentation must be employed. The studies addressed in this topic will range
in size from Angstroms (
˚
) to microns (
m):
˚
m (10
6
m).
We will first address the question of size by asking whether someone with excellent vision
can actually see a membrane. A person with excellent vision can resolve two spots about
0.1 mm apart.
(10
10
m), nm (10
9
m) and
m
m
10
4
m
10
2
10
5
nm
10
6
A
0
:
1
mm
¼
¼
m
m
¼
¼
