Tuesday, September 4, 2007

A sticky situation for Marcsana

Marcsana’s latest response in A creationism vs. evolution discussion,. Part 2 is extremely lengthy and wordy. I feel no need to address most of it here, as it’s just beating a dead horse- most of it is rehashing of the same arguments that have already been presented over and over again- truly “no new information!”- irrelevant side excursions, and failure to address most of the points I’ve already made. I’ll sum up Marcsana’s points in my next post.

However, the last section is so egregious as to demand addressing. It is apparent, when looking over this discussion, that most of Marcsana’s material consists of canned quotes and paraphrases from AIG. When he attempts to deal with something outside of the limited realm of AIG’s predigested responses, it is often obvious that he really does not know what he is talking about. This quote shows a profound lack of understanding of the subject at hand, an ignorance that is truly so appalling as to cast extreme doubts on any of Marcsana’s opinions on anything having to deal with matters biological.

Once again, Marcsana's original is plain text, my responses are in bold.

Let’s look at this quote line-by-line.

Not so fast. Your iron-sulfur surface does not capture and store the energy.

We have already shown that iron sulfide membranes generated in conditions simulating those of the early Earth can hold a tension of 500 millivolts," says Russell. "(That's) quite enough to drive a primitive metabolist
Metal cells may have held the chemicals of life's origin captive

Nor can the conversion mechanism be so simply stated. First, look at my post on your thermal vents. Then remember BOTH posts on Thermodynamics.

None of those posts have anything to do with this system.

The iron-sulfur surface more or less deals with acetate. This is for all intents and purposes an adhesive.

I must ask, Marcsana- have you ever taken a college-level class in any of the life sciences or in organic chemistry? You are somehow confusing acetate (a salt or ester of acetic acid, a vital compound in many organic reactions) with something like polyvinyl acetate, which is an adhesive. This is not a mistake that anyone with any training or education whatsoever in basic biology would make. If you don’t understand something as fundamental as the bare-bones basics of biology, how can you possibly make educated statements on any matters biological? Please don’t try to explain this away as a simple typo or a meaningless slip-up. This is somewhat Zen-like, but if you don’t realize how grave an error you made, you don’t have the knowledge necessary to realize how grave an error you made.

Let’s take a simple lesson in biochemistry and look at acetates and why they are important.

In order for life to exist, metabolism (chemical processes that occur inside cells) must exist. These processes convert energy into energy forms usable by cells (catabolism) or into components of the cells such as proteins (anabolism.)

These conversions occur through what are called “metabolic pathways,” through which the chemicals are transformed by enzymes. These pathways may be linear, such as photosynthesis (converting sunlight, carbon dioxide and water into glucose and oxygen) or cyclical, such as the Krebs cycle.

Many of these metabolic pathways show extreme conservation across phyla. For example, the Krebs cycle (often known as the citric acid cycle) is found in all organisms that utilize oxygen for cellular respiration. Cellular respiration has nothing to do with breathing; it’s how a cell obtains and uses fuel and disposes of the resultant wastes.

Glycolysis is the process through which cells break down glucose into pyruvate, in the process also releasing ATP, the currency of cellular energy. . In the presence of oxygen, the pyruvate is then converted, via pyruvate decarboxylation, into acetyl CoA, which is used in several cellular processes, but primarily in the Krebs cycle, where it provides carbon that is oxidized to form energy. The Krebs cycle is a vital part of the metabolic pathway that transforms nutrients (protein, fat and carbohydrates) into energy, carbon dioxide and water.

So what does this all have to do with acetates? Well, as you might guess from its name, acetyl CoA has something to do with acetates. An acetyl group is formed from acetate. So acetate is a vital compound in the chemistry of life, with the pyruvate decarboxylation reaction just one example of its use. And, quite obviously, it has nothing to do with “adhesives!”

So what does this all have to do with thermal vents?

One of the foremost authorities on the possibility of life first forming in bubbles at thermal vents is Dr. Michael J Russell of NASA and the University of Glasgow. All of the papers which I cite can be found here .

Russell postulates that the precursor to acetyl CoA pathway formed when carbon dioxide and hydrogen reacted with metal sulfides (such as iron sulphate) at hydrothermal vents.
Geologists have suggested that life might have emerged at hydrothermal vents, chemists have shown that metal sulphides such as FeS and NiS can catalyse biochemical reactions in the absence of proteins, and biologists have suggested that the acetyl-coenzyme-A (CoA) pathway of CO2 fixation might be very ancient. New findings from the enzymes at the heart of the acetyl-CoA pathway, carbon monoxide dehydrogenase (CODH) and acetyl-CoA synthase (ACS), indicate that metals and metal sulphides go the biochemical work of CO2 fixation. Here we propose that biochemistry got started when the two volatiles that were thermodynamically furthest from equilibrium on the early Earth – namely, marine CO2 from volcanoes and hydrothermal H2 – met at a hydrothermal vent rich in metal sulphides. In this ‘hydro-
thermal reactor’ hypothesis, a primitive, inorganically catalysed analogue of the exergonic acetyl-CoApathway, using H2 as the initial electron donor and CO2 as the initial acceptor, was instrumental in the synthesis of organic precursors to fuel primordial biochemical reactions. We suggest that primordial biochemistry was housed in an acetate-producing hydrothermal reactor that retained reduced carbon compounds produced within its naturally forming inorganic confines.
“The rocky roots of the acetyl-CoA pathway”
This theory helps explain not only the origin of various metabolic pathwhays that use acetates, but of enzymatic metal clusters that are very similar to those still used by many organisms today.
The slow trickle of hydrogen and carbon dioxide through such chambers and across the iron sulfide catalyst promotes formation of acetate, according to Russell and Martin. Acetate is a key intermediate in virtually all biosynthetic pathways, and in modern cells, enters these reactions tethered to sulfur. In modern bacteria, the two enzymes that make acetate depend on a catalytic core of iron, nickel, and sulfur, arranged almost exactly as they are in the free mineral itself. “In other words,” Russell and Martin have written, these enzymatic metal clusters “are not inventions of the biological world, rather they are mimics of minerals that are indisputably older, and which themselves have catalytic activity in the absence of protein”
Jump-Starting a Cellular World

These vents provided gradients of both pH and temperature that were more favorable to the production of organic molecules than hotter “black smoker” type vents.

The seepages are caused by convection of ocean water through hot crust composed mainly of magnesium and iron silicates (5). Exothermic hydration of hot rock would have maintained the convecting waters at ~100°C and pH ~10 (3). Gradients within such a porous seepage mound, from hydrothermal fluid to ocean, would have been from pH ~10to ~6 and from ~100°C to <20°c.>
“The Importance of Being Alkaline.”

And, to get back to the acetate…this theory also helps explain the origins of two different types of lipid membranes in prokaryotes (bacteria and other life forms without a nucleus) and eukaryotes (all other living things.)
[T]he scientists say that the prokaryotic branches of bacteria and archaea split while still contained within the iron sulfide birthplace. The ancestors of today's bacteria made one kind of lipid membrane, while the ancestors of the archaea generated lipids in a completely different way.
"Both the fatty acid lipids for bacteria and the isoprenoid lipids for archaea start from acetyl-coenzyme A, a truly universal intermediate," says Martin. "The function of the fatty acid and isoprenoid lipids is the same, but the route to get there differs. As a modern example, think of wings in insects and birds; those wings arose completely independently."
Metal cells may have held the chemicals of life's origin captive

Furthermore, the half-lives of adenine, uracil, guanine or cytosine won’t allow for a simple capture.

What in the world are you talking about? Where and how did the nucleobases come into this? Are you somehow thinking that the iron-sulfur system was postulated to “capture” bases? Again, do you understand what you’ve been reading? What you have written is meaningless gibberish.

You haven’t provided anywhere near a sufficient enough response to satisfactorily explain requirements three and four

As I have previously explained rather thoroughly, these “requirements three and four” are obstructionist creationist fabrications, not science. I will deal with them even more thoroughly in my next post.

In short, you need a “machine” already in place that can convert geothermal energy. This, of course, would take time to evolve. But it can’t evolve if the raw geothermal energy is bombarding whatever is in those vents.

Once again, you totally fail to understand the theory- both of the Second Law of Thermodynamics and of thermal vents. Please read what I have written above, plus the various quotes from Dr. Michael Russell, and if you care to address them, please address the exact specifics of the theory that I am discussing and that he has researched.

Think of the skin cancer analogy.

Yes- let’s think about that skin cancer analogy. Thinking about it- questioning its logic, whether it makes sense, whether it is used approipriately or is logically flawed, is exactly the right thing to do!

Hmmm…. “If a person stands out in the sun too long, he or she won’t get more complex. He or she will get skin cancer. Why? Because we can’t harness raw solar power.”

This analogy is utterly meaningless on several points-
- We cannot generalize from humans to the universe. Our abilities to handle raw solar power have nothing to do with the rest of the universe’s ability to do so. A seedling, for example, easily transforms that solar energy into complexity. All over the world, plants provide proof of local increases in complexity.
- It’s wrong, even when applied to humans. We may not be photosynthetic, but we can and do harness raw solar energy! Sunlight –specifically ultraviolet rays- is needed to produce vitamin D in the skin. Sunlight stimulates melanocytes to produce melanin and increase tanning.
- Like it or not, cancer can be an increase in complexity. Thus, cancer cause by sunlight can be viewed as an overall increase in complexity.

So I thought about your analogy. And I found it wanting, illogical, and irrelevant.

DNA and RNA are almost unimaginably complex and this proposed model can’t explain the rise of information. It is far too simplistic.

This argument is called “”the argument from incredulity” or “the god of the gaps.” Just because you cannot explain something doesn’t mean it cannot be explained. Throughout history, various gods were claimed to be the cause of all sorts of things that people could not explain, such as plagues, volcanic eruptions, and mental illnesses. As our scientific knowledge has grown, we have replaced such outmoded beliefs with scientific ones.

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