Biological complexity:citric acid (Krebs) cyclical reactions (Introduction)

by David Turell , Friday, July 01, 2022, 19:09 (666 days ago) @ David Turell

DAVID: Just look at this entry to see the diagrams of the citric (Krebs) cycle which I was taught in med school, to see why a designer is needed:

https://sandwalk.blogspot.com/2019/12/the-evolution-of-citrate-synthase.html#more

This is now the subject of a book explaining the biochemistry of life:

https://www.sciencemagazinedigital.org/sciencemagazine/01_july_2022/MobilePagedArticle....

"The incredible scientific advances centered around DNA, RNA, and proteins have left many people with the impression that the essence of life is found in genetic information. Yet a cell that died seconds ago contains the same genes that it did moments earlier, suggesting that there are other processes at play that bring the inanimate to life. In his latest book, Transformer, biochemist Nick Lane reminds readers in accessible prose that it is life’s dynamic chemistry, its metabolism, that draws inanimate matter into the living state and back again. As Lane puts it, metabolism is not just “what keeps us alive—it is what being alive is.”

"The main hero of the book is the Krebs cycle, a sequence of chemical reactions that most of us were taught releases energy from molecules obtained from the breakdown of sugars or fats, expelling CO2 as a waste product. However, Lane points out that this perspective obscures this vital process’s place at the heart of all biology and life itself.

"Few laypeople know that the Krebs cycle can run in reverse, fixing CO2 and hydrogen gas to produce all the key building blocks of biochemistry—a process as natural and thermodynamically favored as water flowing downhill. Some versions of this reverse Krebs cycle contain a feedback loop that amplifies the quantity of its own chemical constituents. Rather than simply being an engine for the synthesis of the molecules of life, it may thus be more accurate to say that life is what one can make from the Krebs cycle. (my bold)

***

"Lane and others, such as Jack Corliss, Günter Wächtershäuser, Mike Russell, and Bill Martin, speculate that deep-sea hydrothermal vents were life’s birthplace. Some of these researchers argue that a primitive form of the Krebs cycle led to the first living systems and that the cycle may have initially run in the reverse direction. The proton gradients between the inorganic membranes found within these vents may have been key to promoting the chemistry of life, argues Lane."

Comment: I've been long convinced that deep-sea vents were involved in the origin of life. The Kreb's cycle is at the heart of living biochemistry. That is runs backward and forward is a strong indication of a designer at work. How could that have happened by chance? I haven't read this book, but it obviously would help anyone to understand how to look at life through its biochemistry.