Daniel Smith
Posts: 970
Joined: Sep. 2007
|
I know, I know...
You are all brilliant scientific minds - able to master complex arguments and logic - while I'm easily distracted by shiny things.
You are all witty and hilarious - wordsmiths of the highest order - while I am not allowed around sharp objects.
I get it.
Anyway, here is an overview of the amino acid synthesis pathway for E. coli I've been harping about:
Oxaloacetate
(1)
Aspartic Acid* (2) Asparagine*
(3)
(4)
Aspartic ?-semialdehyde (5)(6)(7)(8)(9) Meso-diaminopimelate (10) Lysine*
(11)
Homoserine (18)(19)(20) Methionine*
(12)
Threonine* (13)(14)(15)(16)(17) Isoleucine*
Notes:
Amino acids are marked with an asterisk *
Each number in parentheses represents a discrete biochemical step requiring a unique enzyme.
(While constructing this little map, I noticed that I left a couple amino acids out of my original argument. I've corrected that.)
So boys, here is the challenge:
1. Explain how this amino acid synthesis system in E. coli originated via natural mechanisms.
2. Explain how and why each of the twenty unique enzymes came to be. To further complicate matters let me add here that enzymes are proteins, and proteins are made from (you guessed it) amino acids! So enzymes are required to make amino acids and amino acids are required to make enzymes. A divine catch-22!
3. Explain how each of the twenty steps in the biochemical pathway came together in the correct order to form these essential amino acids.
4. Tell us what the immediate precursor to the current system was.
5. What were all the intermediate steps? Remember that this explanation must account for each enzyme and each step.
6. Explain how each enzyme came to be regulated. These enzymes are only produced as needed. If enzymes were unregulated you could either have too many of them, causing a chemical imbalance or even cell rupture; or too few, which would stop amino acid synthesis. How did this regulation come about?
Let me be honest though: at this point, I'm not expecting fine details from any of you. I'll be happy with a guess. Just take a guess! Preferably one that goes somewhat beyond "oldmanintheskydidntdoit"! At least try to imagine a scenario that would result in the current system.
Remember, this is one of the simplest systems in one of the simplest unicellular lifeforms on the planet. It is a basic, foundational system - not a highly complex, multicellular system such as the vision system, the circulatory system, or even skin, teeth or toenails. Those systems are orders of magnitude more complex than this one.
In my opinion, if you can't explain something as simple as this within the bounds of your theory, you should find a new theory.
--------------
"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance." Orville Wright
"The presence or absence of a creative super-intelligence is unequivocally a scientific question." Richard Dawkins
|
