Mendel in the Kitchen A Scientist's View of Genetically Modified Foods (2004) / Chapter Skim
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4 Genes and Species
4 Genes and Species
Pages 67-84
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From page 67... ...
Rather than following Edgar Anderson's whimsical suggestion that the wheat genus be renamed Aegilotriticopyron, to give due credit to its roots, taxonomists decided to demote Aegilops squarrosa and the other 20 or so Aegilops species and put them into the wheat genus, Triticum. Aegilops squarrosa was duly renamed Triticum aegilops.
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From page 68... ...
Seeking to include evolution in the definition of species, paleontologist George Gaylord Simpson called a species "a series of ancestor descendent populations passing through time and space independent of other populations, each of which possesses its own evolutionary tendencies and historical fate." The problem with Simpson's definition is that there are gaps in fossil records, and such gaps can create arbitrary boundaries between species. Searching for a better definition of "species," we simply find more definitions.
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From page 69... ...
In the grocery store, cabbages, kale, kohlrabi, cauliflower, broccoli, and Brussels sprouts are all neatly divided into their own bins. Diners who ordered Brussels sprouts in a restaurant would be outraged if they were served cabbage instead.
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From page 70... ...
in a Belgian garden in 1750. If grown carefully, with no chance of sharing pollen, each of these varieties of Brassica oleracea -- as well as all their subtypes, such as
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From page 71... ...
Genetic engineering is not constrained by these rules and crosses all boundaries set in place by natural law." To support their case, they quote John Hagelin, a physicist: "When genetic engineers disregard the reproductive boundaries set in place by natural law, they run the risk of destroying our genetic encyclopedia, compromising the richness of our natural biodiversity and creat
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From page 72... ...
This medieval concept of species was a major stumbling block for the theory of evolution when it was first introduced in the mid-nineteenth century. The French scientist Jean-Baptiste Lamarck set forth in 1809 the idea that creatures had changed -- or evolved -- since God created Earth.
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From page 73... ...
Like the notion of a species, the concept of the gene went through many revisions before a scientific consensus was reached and, like species, it has changed dramatically since then, as we have learned more about what actually occurs inside a cell. The field of genetics, the science of heredity, began in 1900 when Hugo De Vries and Carl Correns rediscovered the pea experiments Mendel had done in his monastery garden half a century earlier.
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From page 74... ...
Because half of the parents' hereditary units called for round seeds and half called for wrinkled seeds, one quarter (half of a half) of the offspring would receive only roundness units and another quarter would receive only wrinkliness units.
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From page 75... ...
Each name had an earlier theory attached to it, and none of them satisfied everyone. Then in 1909 Danish botanist Wilhelm Johannsen published his work on beans.
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From page 76... ...
Strasburger had described spindly structures that, as the cell divides, first lengthen, then shorten again to form compact little rods. In 1888 botanist Wilhelm Waldeyer noticed that these rods took up a stain well, so he named them "chromo" (colored)
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From page 77... ...
If a fruit fly offspring had white eyes, it was also likely to have a yellow body. The reason, Morgan believed, had to do with where the genes physically resided in the cell.
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From page 78... ...
The milk bottles were hardly a high biosafety-level containment facility for these genetic experiments. "Near the entrance of the room a stalk of bananas hung conspicuously, serving as a center of attraction for the numerous fruit flies that had escaped from their milk bottles or that had bred themselves, without the benefit and direction of science, in the garbage can that was never thoroughly cleaned," wrote Ian Shine and Sylvia Wrobel in their biography of Morgan.
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From page 79... ...
. In 1944 Oswald Avery, Colin MacLeod, and Maclyn McCarty at the Rockefeller Institute for Medical Research in New York carried out experiments that led to the identification of the chemical nature of genes.
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From page 80... ...
As James Watson and Francis Crick announced in a short paper in Nature in 1953, DNA is a double helix, rather like a spiral staircase. Watson and Crick had earlier proposed to their London colleagues, Rosalind Franklin and Maurice Wilkins, that DNA was a triple helix.
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From page 81... ...
The analogy is, of course, not exact. A true book contains many pages of sentences folded in upon each other: you read across a line of letters, then go to the beginning of the next line.
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From page 82... ...
Drosophila itself has 13,000 genes.Venter concluded: "The modest number of human genes means that we must look elsewhere for the mechanisms that generate the complexities inherent in human development." Nor are there only genes in the genome, if by gene we mean the sequence that codes for a protein. Of the string of 3.2 billion ATGCs that make up the human genome, for example, only a tiny fraction-between 1.1 and 1.4 percent -- actually codes for the organism's proteins.
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From page 83... ...
With less starch, the pea seed wrinkles as it dries. And in the early 1980s, it was an understanding of transposons -- what they are and what they can do -- that inspired scientists to harness the soil bacterium Agrobacterium tumefaciens to carry new genes into plants.
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