Re: Dinosaur Protein

[dinoboygraphics@aol.com]

> > > And, why does DNA not hold up so well?<<<

Some good answers have already made it to the list about the molecular 
reasons why DNA is suceptible to more rapid breakdown.  As it's a 
biology-related mailing list, I wanted to point out that there are 
underlying evolutionary reasons for is.  As many of you know DNA is not 
simply run from front to back through the protein synthesis machinery.  
Instead protein synthesis responds to a complex network of hormones and 
other intercellular communication, intracellular changes in chemical 
makeup, and environmental cues.  DNA has to be able to be opened easily 
(e.g. unwrapped from histones and the needed portion transcribed), and 
this "flexibility" in conformation is synonymous with breaking down 
easily.

Collagen, on the other hand, is the tough, non-elastic protein in 
connective tissue, and has been selected to the opposite selective 
pressures the previous several billion years.  In order to retain its 
shape and hold...whatever it's holding...in place, it needs to not 
respond to chemical alterations, and hence has evolved to be relatively 
innert.

So it really has to be this way, or else organisms as we understand 
them would not work.  We could even hypothesize that if future 
paleontologists are ever working on a very different form of life (that 
evolved separately from Earth), that we will again be far more likely 
to recover connective tissue proteins, but much less likely to recover 
intact whatever molcule is used to store the instruction set for 
producing and maintainng an organism.


Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com

________________________________________________________________________
AOL now offers free email to everyone.  Find out more about what's free 
from AOL at AOL.com.