Biology Reference
In-Depth Information
Fig. 11.9 The relation between the amounts of coding (C) versus noncoding (N) DNA of 67
prokaryotic and 733 eukaryotic species in units of base pairs (Reproduced from Fink et al. 2007)
where
a
is proportionality constant and
w
is a “critical exponent” postulated to be
unique to organisms, reflecting the functional characteristics of their genomes.
For the prokaryotic genomes which consist of mostly drp genes and are devoid
of any dr- and d-genes:
w
¼
1
(11.6)
For eukaryotic species with only drp- and dr-genes:
w
¼
2
(11.7)
For eukaryotic species with drp-, dr-, and d-genes:
2
<
w
<
10
(11.8)
It is interesting to note that drp- and dr-genes each contribute one unit to the
numerical value of
w
, leaving d-genes to contribute one to about eight units to the
numerical value of
w
. It is suggested here that the numerical values of
w
greater
than 2 be referred to as “excess critical exponent (ECE).” Although the physical
meaning of ECE defined here is not yet clear, ECE may be related to the
number of
subunits in multisubunit complexes of enzymes
such as those participating in signal
transduction networks, translation, protein degradation, transcription (cf. transcrip-
tosomes), transcript degradation (cf. degradosomes), and nuclear pore complexes.
The number of the subunits constituting an enzyme complex ranges from 30 to 100.
If this interpretation of ECE is correct, there may be a profound difference between
