6 results found.
... Science Frontiers ONLINE No. 34: Jul-Aug 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Dna Even More Promiscuous It was a surprise when DNA sequences from mitochondria in yeast cells were discovered setting up shop in the nuclear genomes (i .e ., the normal genetic endowment of the cell nucleus). Now biologists find that DNA sequences in many species regularly and frequently hop from one genome to another. Genetic material from cell chloroplasts mix with that of the mitochondria and that of the normal nucleus in what seems to be a free-for-all. This genome hopping has earned DNA the adjective "promiscuous." The significance of DNA promiscuity is to be found in the general belief that the cell's mitochondria and chloroplasts were once independent biological entities that, in the course of life's development, invaded or were captured by cells and have led a symbiotic life ever since. The mitochondria and chloroplasts perform certain important functions in the cell but were thought, until now, to retain considerable genetic independence. (Lewin, Roger; "No Genome Barriers to Promiscuous DNA," Science, 224:970, 1984.) Comment. The promiscuity of DNA raises speculation that other DNA-bearing entities that invade the body, especially the viruses, may transfer their DNA to the host, and conceivably vice versa. With DNA apparently much more promiscuous than believed earlier, the role of disease in the development of life takes on a new importance. In other words, all species can potentially exchange genetic ...
Terms matched: 1 - Score: 123 - 15 May 2017 - URL: /sf034/sf034p10.htm
... Science Frontiers ONLINE No. 25: Jan-Feb 1983 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Promiscuous Dna The cells of plants (photosynthetic eukaryotes) are genetically the most complex that biologists have discovered. Each cell has three genetic systems: its own, that of the chloroplasts; and that of the mitochondria. It is supposed that the chloroplasts and mitochondria were once free-living cells that linked up with the embryonic plant cell to form a symbiotic partnership, with the host "plant" cell being the dominant member. Up until now, the three genetic systems were thought to be discrete, each going down its own pathway. But chloroplasts genes have now been found inside plant mitochondria, overturning conventional wisdom. To sum it all up, DNA seems promiscuous -- no respecter of privacy and breaking down all isolating genetic barriers. This discovery at once raises a dozen questions. For example, are mitochondria genes in chloroplast cells? How far does this promiscuity go? Can the same thing happen in higher organisms; say, with humans and symbiotic microorganisms or even not-so-symbiotic disease organisms? Is there no stopping this DNA? (Ellis, John; "Promiscuous DNA -- Chloroplast Genes inside Plant Mitochondria," Nature, 299:678, 1982.) From Science Frontiers #25, JAN-FEB 1983 . 1983-2000 William R. Corliss ...
Terms matched: 1 - Score: 106 - 15 May 2017 - URL: /sf025/sf025p06.htm
... Science Frontiers ONLINE No. 25: Jan-Feb 1983 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology A Far-wandering Lost Tribe? Manifestations of Earth Energy At Megalithic Sites? Astronomy More on "the Massive Solar Companion" Lageos Falls Too Fast Biology Learning by Injection Promiscuous DNA Why Don't We All Have Cancer? Review of the Tektite Problem The Andes Ice Islands Geology Three "proofs" of A Young Earth Geophysics Gas Hydrates and the Bermuda Triangle Psychology Schizophrenia and Season of Birth Chemistry & Physics Anomalons Are Lazy Or Fat ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf025/index.htm
... Science Frontiers ONLINE No. 34: Jul-Aug 1984 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology Ancient Wisconsin Astronomers The Guadeloupe Skeleton Revisited Pouring A Pyramid A Demurrer From the Epigraphic Society Ancient Old-world Lamps Turn Up in New England Astronomy Does String Hold the Universe Together? The Big Bang As An Illusion A Gathering of Quasars Biology Our Aquatic Phase! Dna even more promiscuous A Note on Perfect Pitch Sunspots and Disease Are Parasites Really the Masters? Geology The Carbon Problem Behind Magnetic Flip-flops Geophysics Aggressive Ball Lightning Low-level Aurora? The Marfa Lights Psychology The Mind's Control of Bodily Processes Hostage Hallucinations Techno-jinx Unclassified Strange Object in the Sky ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf034/index.htm
... Baker and Bellis draw upon their own studies and classifications of sperm types as well as research by R.A . Beatty and D. Ralt. They assert that sperm come in at least four varieties: "Fertilizers," the egg-penetration specialists, "Blockers," the ones that construct copulatory plugs to prevent further insemination, "Search-and destroy sperm" that hunt down as kill "enemy" sperm from other sources, "Family-planning sperm" that kill all sperm. One can liken this array of sperm types to polymorphic ant colonies with their castes of workers, soldiers, and queen. Baker and Bellis go further and suggest that the numbers of each sperm type are under the control (certainly not conscious control) of the males. For example, where promiscuity is observed, as is common in chimpanzee troops, the numbers of seek-and-destroy sperm are very high. All this out of a short review! Unfortunately, the book itself lists at $78.95, and we don't have a copy. (Sozou, Peter D.; "Mating Games," Scientific American, 274:102, January 1996) Comments. Exercising self control, we add only two comments. First, these specialized sperm cannot be as simple as those drawn in the biology books. The search-and-destroy type must have evolved biochemical "devices" that find, identify, and destroy other sperm and maybe even defend itself. Second, one should not ignore the eggs, which are much larger and likely more sophisticated ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf104/sf104p02.htm
... -Scale Extinctions Polyphyletic Origin of Reptiles Warm-Blooded Dinosaurs Mammal-Like Reptiles Snakes with Legs Hairy and Feathered Dinosaurs Origin of Turtles Dinosaur Feeding Habits Correlated with Origin of Flowering Plants Mysterious Reptile Footprints Caecelian Origin Fish-Reptile Transition Fossils Crocodile Origin (Chemistry Contradicts Fossils) Ichthyosaur-Fish Convergence Dinosaurs with Bird-Like Bones Dinosaur Species Separated by Oceans Evolution of Flight Evolutionary Stasis Fish-Amphibian Transition Fossils Filter-Feeding Dinosaurs Sudden Appearances in the Fossil Record Orthogenesis Preadaptation in Reptiles Many Examples of Convergent Evolution Frog Origin Perplexing Ruminating Dinosaurs Unknown Purpose of Back Fans on Dinosaurs Origin of Fins on Marine Reptiles Evolutionary Stasis Vertical Flexure in Marine Reptiles Dinosaurs with Trunks Dinosaurs with Whale-Like Nostrils Web-Footed Dinosaurs BRF BODILY FUNTCIONS Parthenogenesis, Virgin Birth [BRA All-Female Species] Advantages of Female Promiscuity Survival of Freezing Tadpoleless-Frog Species Frog-Brooding and Tadpole Care Incubating Pythons Limb Regeneration Nursing of Young (Caecilians] How Are Enormous Prey Digested? Live-Bearing Lizards Warm-Blooded Leatherbacks Reptiles Never Stop Growing Giant Tadpoles That Become Tiny Frogs! Metamorphosis Enigmas Newt-Eye Regeneration Frogs without Tadpole Stage Live Birth in Frogs Infertile Eggs Laid for Food BRG GENETICS Green Turtle Populations Have Very Small Genetic Differences Homeobox-Gene Control of Body Plans Strong Convergence in Island Lizards [BRD] Chromosome-Number Effect upon Amphibian Development Frog Genes Jump between Species "Cryptic Species": Look Alike But Genetically Different Marked DNA Differences within Same Species BRI INTERNAL SYSTEMS AND STRUCTURES Low Antibody Diversity in Reptiles and Amphibians Magnetite Concentrations BRO ORGANS Lungs Used for Hearing Independent Eye Motion Lungless Salamanders Amphibian Lateral Lines Reptile ...
Terms matched: 1 - Score: 5 - 15 May 2017 - URL: /cat-biol.htm
