the coiled spring

[...]... given him the capacity to present the modern synthesis in developmental biology to the reader in clear and accessible language The Coiled Spring starts with the most fundamental of premises in modern developmental biology: All cells contain the same genetic information He then logically progresses to ask, if this is so, why all cells in the body are not the same The rest of the book (and indeed embryogenesis)... understanding of the way in which an embryo forms In addition, the book includes boxes in which the contributions of some of the pioneers of the field are highlighted These go beyond biographical data and descriptions of their work and focus on their personalities and motivations These are only a small subset of the people who have had a major impact on the field, but including them gives the reader a... bipartite structure The Central Dogma of Biology s A Gene Analogy s 17 s A gene can be likened to an electric appliance such as a lamp, TV, or toaster The functional portion of the device is similar to the coding region of the gene (i.e., the light fixture of a lamp, the screen of the TV, or the heating coils of the toaster) The switches controlling these devices are analogous to the regulatory regions... dimensional forms The other functional part of the gene, called the regulatory or control region, is an on/off switch that determines whether or not the coding region of the gene will actively synthesize its protein product in a given cell type A gene actively directing the synthesis of its protein product is said to be “expressed” or “switched on.” When the protein is not being made, the gene is said... of the final protein product of the gene DNA is replicated and transcribed in the nucleus of the cell The nucleus contains densely packed DNA and is surrounded by a porous nuclear membrane, which permits newly synthesized RNA molecules to exit the nucleus and enter the main cellular compartment called the cytoplasm The cytoplasm is enclosed by a watertight cell membrane separating the inside of the. .. move down the DNA to the other end, inserting complementary bases into the growing strand as they go DNA polymerase and RNA polymerase are very different, however, in two important respects First, when DNA is replicated, as opposed to transcribed, both strands of the complete genome are copied The result of replication is the synthesis of a duplicate copy of the entire genetic information of the organism... the cell from the outside world The second step of reading the genetic information is called translation and takes place in the cytoplasm (see Fig 1.5) The term translation reflects the fact that one molecular language is being translated into another The s 19 20 s Chapter 1 first language, that of DNA or RNA, is represented by the order of the four bases Since DNA and RNA obey essentially the same base... implication of the strict complementarity between bases in double-stranded DNA is that if the sequence of bases on one strand is known, one can immediately deduce the sequence of bases on the opposite strand In other words, each strand of DNA carries all the information necessary to recreate the other This structural fact has deep ramifications for the way in which DNA molecules are replicated In their famous... writings of the ancient Egyptians and Mesopotamians Among the Greeks, Aristotle, often considered the first true embryologist, opened bird eggs at different stages of incubation and wrote careful descriptions of the process of ontogeny Hippocrates, the father of modern medicine, also used animals to form the basis of a descriptive embryology Yet in the thousands of years since then, while the descriptions... have been proposed over the years to explain how information stored in the egg might govern development The first model, which represents one extreme end of the spectrum of possibilities, is that the egg is far more organized than it appears to be The essence of this hypothesis is that the information for where to make various adult structures such as the head versus tail, the back versus belly, or .