The Machinery of Life

The Machinery of Life

David S. Goodsell

Language: English

Pages: 168

ISBN: 0387849246

Format: PDF / Kindle (mobi) / ePub


Imagine that we had some way to look directly at the molecules in a living organism. An x-ray microscope would do the trick, or since we’re dreaming, perhaps an Asimov-style nanosubmarine (unfortunately, neither is currently feasible). Think of the wonders we could witness firsthand: antibodies atta- ing a virus, electrical signals racing down nerve fibers, proteins building new strands of DNA. Many of the questions puzzling the current cadre of sci- tists would be answered at a glance. But the nanoscale world of molecules is separated from our everyday world of experience by a daunting million-fold difference in size, so the world of molecules is completely invisible. I created the illustrations in this book to help bridge this gulf and allow us to see the molecular structure of cells, if not directly, then in an artistic rendition. I have included two types of illustrations with this goal in mind: watercolor paintings which magnify a small portion of a living cell by one million times, showing the arrangement of molecules inside, and comput- generated pictures, which show the atomic details of individual molecules. In this second edition of The Machinery of Life, these illustrations are presented in full color, and they incorporate many of the exciting scientific advances of the 15 years since the first edition.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

also binds and delivers other carbon-rich molecules such as steroid hormones and drugs. This can be very important when deciding on the proper dosage for a given drug. If it binds strongly to serum albumin, most of it will be hidden away in the protein and won’t get to its proper site of action. However, it can also prolong the action of a drug. Serum albumin creates a long-lasting reservoir of drug, which is slowly released as it continues to circulate through the blood. Serum albumin also

by viruses and shuts down protein synthesis in an infected cell. Since all protein synthesis is stopped, the cell will die, but this will ensure that no viruses are made as well. Many viruses, however, fight back by creating a protein that specifically disables Pkr, keeping the protein synthesis machinery running and making more viruses. Poliovirus and Rhinovirus 129 Remarkably, these few ingredients—a tiny time bomb composed of RNA and protein, barely the size of a ribosome—are all that is

them between enzymes involved in fat metabolism, and alcohol dehydrogenase uses NAD in reactions that destroy (or in bacteria, to create) alcohol (left, 5,000,000 X; right, 20,000,000 X) Vitamins 145 Fig. 9.4 Vitamin D Vitamin D is formed from cholesterol in a reaction that requires ultraviolet light. It acts as a hormone by entering cells and binding to receptors in the nucleus. These receptors bind to DNA and direct the formation of proteins involved in calcium metabolism (top, 20,000,000

15 minutes to cross the room! In this time, you may be pushed all over the room, perhaps even back to your starting point a few times. This is similar (although molecules do not have a goal in mind) to the contorted path molecules take in the cell. You might ask how anything ever gets done in this chaotic world. It is true that the motion is random, but it is also true that the motion is very fast compared to the motion in our familiar world. Random, diffusive motion is fast enough to perform

strongly with water. The rest of the molecule is composed primarily of carbon and hydrogen (colored white), which is hydrophobic and does not interact strongly with water. When lipids are mixed with water, they separate into small droplets (or lipid bilayers, as described later in the chapter), minimizing the contact with the surrounding water. At the bottom, many phospholipids have coalesced into a compact globule, with all the hydrophobic parts sheltered inside Nucleic Acids 13 The large

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