Freethought & Rationalism Archive

pz · 01-29-2003, 08:17 PM

Quote:

Originally posted by never been there

For example, a cell deprived of other sources of nutrition but having lactose available must express a lactase gene. A simple one-gene, one-protein problem. It should be well addressed in various texts at various levels.

Well, yeah. It has been for 40 or so years, since Jacob & Monod worked out one model.

Of course, it was a multiple-gene, multiple-protein answer.

Quote:

The answers to rest of your questions derive from that simple case.

Uh, actually, no. Everything has gotten much more complicated, and none of it is derivable from one simple premise. Sorry.

Late_Cretaceous · 01-31-2003, 11:29 AM

Q: How does the cell work?
A: Very well, thank you.

A good book to check out of the library is "the Molecular Biology of the Cell" By ALberts, Bray, Lweis, Baff, Roberts and Watson

lpetrich · 01-31-2003, 01:31 PM

To me, at least, molecular mechanisms often have a Rube-Goldberg quality.

One very interesting curiosity is ATP. That's adenosine triphosphate, and it's an important energy intermediate. The energy resides in the phosphate-phosphate bonds, and the rest of the molecule, a RNA nucleotide, is simply a handle. And ATP is rebuilt with the help of energy-metabolism reactions.

So why use a RNA nucleotide as a handle? This, and other odd occurrences of RNA and RNA-like molecules, has suggested the former presence of an "RNA world", where RNA was both informational macromolecule and enzyme.

DNA, by comparison, is a later invention; DNA nucleotides are produced from RNA ones, and DNA-replication systems were apparently developed in detail more than once.

Boro Nut · 02-03-2003, 05:02 AM

Quote:

Originally posted by I ate Pascal's Wafer
How does the cell work

Basically, you make sure there is only one way in and you keep the door locked. Simple really.

Boro Nut

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01-31-2003, 11:29 AM	#12
Late_Cretaceous Veteran Member Join Date: Oct 2001 Location: Alberta Posts: 1,049	Q: How does the cell work? A: Very well, thank you. A good book to check out of the library is "the Molecular Biology of the Cell" By ALberts, Bray, Lweis, Baff, Roberts and Watson

01-31-2003, 01:31 PM	#13
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	To me, at least, molecular mechanisms often have a Rube-Goldberg quality. One very interesting curiosity is ATP. That's adenosine triphosphate, and it's an important energy intermediate. The energy resides in the phosphate-phosphate bonds, and the rest of the molecule, a RNA nucleotide, is simply a handle. And ATP is rebuilt with the help of energy-metabolism reactions. So why use a RNA nucleotide as a handle? This, and other odd occurrences of RNA and RNA-like molecules, has suggested the former presence of an "RNA world", where RNA was both informational macromolecule and enzyme. DNA, by comparison, is a later invention; DNA nucleotides are produced from RNA ones, and DNA-replication systems were apparently developed in detail more than once.

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