This book can be seen as a supplement to the previous column. It is suitable as a beginner's map for physics students to get started with biology.
As mentioned earlier During our summer reading club, the second book we read was How Life Works by Philip Ball. This book has not yet been translated into Chinese, so I translated it while reading it.
The author Philip Ball is a chemistry and physics major, but he has been the biology editor of Nature for many years. This blog has translated a column by him, "Why Physics Is Not a Discipline"
On the one hand, the author disagrees with biologists' refusal to reduce biology to a subset of physics. On the other hand, he is dissatisfied with physicists' repetition of "physics is the law of everything" while standing idly by when it comes to complex systems like biology. He can be said to be a biophysicist who is consistent with both idea and action.
This book can be seen as a supplement to the previous column. (Many researchers' names appear in both works.) It is suitable as a beginner's map for physics students to get started with biology.
One of the phenomena that distinguishes biological systems from ordinary physical systems at similar spatial scales is their multi-level organizational structure - atoms that fully follow the laws of physics and chemistry form biological macromolecules; biological macromolecules then form organelles with specific functions, which work in cells as the basic unit of life; cells of the same type gather into tissues, and different types of cell tissues form organs, and then form systems and organisms...
This is basically the narrative thread of this book. The book has 11 chapters, and I originally wanted to give each chapter a corresponding topic of the APS March meeting. When I went back to organize the meeting notes, I realized that the settings of the sub-venues are not exactly the same every year. The number is far more than the number of chapters in this book, and the focus of the book does not completely overlap.
The first 6 chapters, or nearly half of the book, are about molecular biology, while cell biology and developmental biology together make up the remaining half. This shows that the former has much more fruitful research results than the latter two.
This difference in the amount of information should not be understood as evidence that the former is superior to the latter. Instead, it is similar to survivor bias, because scientists are more likely to obtain clear results in molecular biology, which attracts more scientists to participate in it, and positive feedback has obtained more results. As the author said in Chapter 4:
The popular view that science is the process of studying what the world is like needs to be given an important qualification: science tends to be the study of what we can study. Its focus is biased toward those aspects of the world for which we have experimental and conceptual tools.
In molecular biology, after the discovery of the DNA double helix, Watson and Crick each expressed the "central dogma".
Watson's version is simple and crude, biological information goes from DNA to RNA, and from RNA to protein. This statement is no longer valid today because of the discovery of RNA replication and reverse transcription, as well as the spread of prions.
Crick's version simply says that after genetic sequence information flows to proteins, it will no longer flow to other proteins or return to nucleic acids. This statement is still valid today, and even the replication of prions does not constitute a falsification.
The reason why the first five chapters of this book are so long is mainly to describe how many extraordinary details there are in the specific implementation of this law. In short, the metaphor of "genes are the blueprints of biological systems" is not correct.
"Genes" are defined as protein-coding DNA fragments, but there are a lot of other contents in DNA molecules - some of them are not transcribed at all, some only rely on transcribed RNA molecules to function, and some even only need the transcription itself to interfere with other DNA fragments to complete their tasks...
Even in the most orthodox DNA → RNA → protein, the coding DNA is not a blueprint for the corresponding protein, but rather a parts list containing sequence information.
The amazing thing is that with just such an ordered list of parts, organisms can produce proteins with spatial structures and biological functions.
What is even more amazing is that many proteins do not have a clear and orderly structure. Some of these proteins are useless and harmless, so they have not been eliminated by evolution. Some can still perform biological functions even without a structure.
Such a miracle can happen mainly because the above biological information jointly assumes the same [meta-information] (what-is-intelligence-not-same-as-intelligence-is-what), that is, the cellular environment surrounded by the membrane structure and the physical and chemical laws that govern this environment.
Therefore, the author is a cell-centrist and disagrees with the book "The Selfish Gene" which discusses genes as the main body of the biological system. He believes that cells can be said to be living systems, while genes are not alive.
The contents of the following chapters are either classic results that have been seen in biophysics courses or are mainly metaphysical discussions. This is mainly because physics lacks recognized and effective mathematical tools for emergence and purpose, so this article will omit them.
In short, there is a broad field in cell biology and developmental biology with great potential.
PS: I'd like to say one a little more about the central dogma:
If we believe Nick Lane's [inference of the process of cell emergence] in "The Vital Question" (nick-lane-the-vital-question) - that is, metal ions near alkaline hydrothermal vents catalyzed early biochemical reactions, and today's enzymes are modified based on metal ions - then there must be a process of burning biological information from proteins to genetic information molecules. Of course, this process is not necessarily completed by cells, and it is not necessarily possible to observe the remains of substances involved in this process in today's cells.
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