How Is Information Content Measured

[Freedom777]

http://www.answersingenesis.org/home/area/feedback/negative_10september2001.asp

 

[fragmentsofdreams]

If you're too lazy to post anything other than a link, why shouldn't I be lazy and not read it?

 

[JohnR7]

Yesterday at 11:59 PM fragmentsofdreams said this in Post #2

If you're too lazy to post anything other than a link, why shouldn't I be lazy and not read it?

It is just some boring biology stuff. Maybe you would find that scientific stuff not to be of interest.

 

[Cantuar]

Since it's from AnswersinGenesis, I doubt it's "just" biology.

 

[Frumious Bandersnatch]

I have to just post a link and run but I have no time right now.

For a different perspective see

http://www.talkorigins.org/origins/postmonth/feb01.html

The Frumious Bandersnatch

 

[lucaspa]

Yesterday at 11:27 PM Freedom777 said this in Post #1

http://www.answersingenesis.org/home/area/feedback/negative_10september2001.asp

What we have with Spetner is an example of the shell game combined with the construction of a strawman.

"The information content of the genome is difficult to evaluate with any precision. Fortunately, for my purposes, I need only consider the change in the information in an enzyme caused by a mutation. The information content of an enzyme is the sum of many parts, among which are:
* Level of catalytic activity
* Specificity with respect to the substrate
* Strength of binding to cell structure
* Specificity of binding to cell structure
* Specificity of the amino-acid sequence devoted to specifying the enzyme for degradation
These are all difficult to evaluate, but the easiest to get a handle on is the information in the substrate specificity."

The first sentence is the correct one.  As Spetner notes there are several ways to measure information content, even with an enzyme.  What Spetner does is pick just one of them and say that all the information is that.

Spetner picks substrate specificity.  He then goes on to give an example of an enzyme that metabolizes ribitol.  A mutant form of that enzyme can also metabolize xylitol.

"The mutant enzyme had an activity large enough to permit the bacterium to live on xylitol alone. Fig. 1 shows the activity of the wild-type enzyme and the mutant enzyme on both ribitol and xylitol."   Spetner sets up the situation that this would be an increase in information because the mutant enzyme could then become more specific to xylitol.  He then destroys his strawman by noting that the mutant enzyme also has activity toward  L-arabitol:

"Burleigh and his colleagues also measured the activities of the two enzymes on another similar sugar, L-arabitol, and the results of these measurements are shown in Fig. 2. With the additional data on L-arabitol, a different picture emerges. No longer do we see the mutation just swinging the activity away from ribitol and toward xylitol. We see instead a general lowering of the selectivity of the enzyme over the set of substrates."

So, using his criteria of substrate specificity as the sole measure of "information", he concludes that there is a lowering of information.

But what happens if we look at the first criteria in Spetner's list?  Level of catalytic activity.  Now we have increased level of catalytic activity because the enzyme is catalyzing three reactions, not just one.  Is the ability to catalyze 3 reactions instead of just one an increase in information?  Intuitively, we would say YES.  Just as a Optical Recognition Program that can read standard type and longhand script has more "information" than a program that can only read type.

Watch out for con jobs, Freedom777.  Spetner has one.

Oh, yes, Spetner has not shown that, now that substrate specificity is broadened to include xylitol and L-arabitol, that further mutations could not eliminate the specificity for L-arabitol and make the mutant specific only for xylitol.  So the validity of NDT, even by Spetner's criteria, is still intact.