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The Ribosome: A Record of Evolution
Space Ref (press release)
In a new study co-funded by the NASA Astrobiology Institute, scientists compared three-dimensional structures of ribosomes from a variety of species of varying biological complexity, including humans, yeast, bacteria and archaea. The team found …
DNA encodes the information necessary to make all the proteins in a cell, but the vast majority of the DNA in a cell is non-coding DNA, in the past sometimes referred to as ‘junk’ DNA. … Mar. 31, 2014
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The Cells That Changed The Earth
Some of the oldest cells on Earth are single-cell organisms called bacteria. Fossil records indicate that mounds of bacteria once covered young Earth. Some began making their own food using carbon dioxide in the atmosphere and energy they harvested from the sun. This process (called photosynthesis) produced enough oxygen to change Earth’s atmosphere. Soon afterward, new oxygen-breathing life forms came onto the scene. With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen. Bacteria are single-celled organisms with a circular DNA molecule and no organelles.
NCSE is pleased to offer a free preview (PDF) of David M. Hillis, David Sadava, H. Craig Heller, and Mary V. Price’s new textbook Principles of Life (Sinauer Associates and W. H. Freeman, 2010). The excerpt constitutes the whole of chapter 15, “Mechanisms of Evolution,” and offers as seven “key concepts” the principles that evolution is both factual and the basis of broader theory; that mutation, selection, gene flow, genetic drift, and nonrandom mating result in evolution; that evolution can be measured by changes in allele frequencies; that selection can be stabilizing, directional, or disruptive; that genomes reveal both neutral and selective processes of evolution; that recombination, lateral gene transfer, and gene duplication can result in new features; and that evolutionary theory has practical applications.
The publishers proclaim, “Numerous recent studies … confirm what a growing number of educators already know: the typical majors biology textbook has become too long, too detailed, and too expensive. … Written in the spirit of the reform movement that is reinvigorating the introductory majors course, Principles of Life cuts through the thicket of excessive detail and factual minutiae to focus on what matters most in the study of biology today. Students explore the most essential biological ideas and information in the context of the field’s defining experiments, and are actively engaged in analyzing research data. The result is a textbook that is hundreds of pages shorter (and significantly less expensive) than the current majors introductory books.”