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noha

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Everything posted by noha

  1. Hello, I have a question from a book called Models of mind by Grace Lindsay Here the writer talks about the difference between biologists and mathematicians and I couldn't get the point here: Biologists study living things that are abundant with specific traits and nuanced exceptions to any rule. Mathematicians – driven by simplicity, elegance and the need to make things manageable – squash that abundance when they put it into equations.
  2. Hello, I want to know the meaning of discharge and gradient in the following context: In the absence of sunlight, vent chemistry supports chemolithotrophic prokaryotes that synthesize sugars by oxidizing hydrogen sulfide and other geofuels including hydrogen, methane, ammonia, ferrous iron, and manganese. (This is analogous to the photosynthetic capture of CO2 powered by electrons obtained from water and energized by light absorption.) According to one model, the discharge of alkaline water through the porous chimneys of white smokers would have created a natural pH gradient in ancient oceans that might have served as a foundation for the origin of cells. I think discharge means flow gradient : gradual change not sudden change, what do you think?
  3. I can't get your point, could you please clarify this? you mean that unsustainable refers to the imbalance?
  4. Hello, I want to know what is meant by unsustainable in the following context from a book called Microbiology: a very short introduction. Soils exposed by deforestation lack the physical structure, chemical composition, and indigenous populations of microbes needed to cultivate consecutive harvests of cereals and other food crops. Intensive grazing of cattle on deforested land is similarly unsustainable. Even in areas where soils are exceedingly rich, crop productivity falls without soil amendment with organic matter and inorganic fertilizers. is it related to the continuity Intensive grazing?
  5. Hello dears, I'd like to understand what is meant by Oxygen has been quenched in the following context and the overall meaning of the context: The nature of the first cells is a subject of enthusiastic conjecture in the absence of objective data beyond the evident presence of life today. The relative timing of the origin of archaea and bacteria is unknown, but fossils show that filamentous prokaryotes resembling today’s cyanobacteria had evolved at least 3.5 billion years ago. It is possible that these microbes performed oxygenic photosynthesis, but measurements of radioactive isotopes show that the sharp rise in atmospheric oxygen known as the Great Oxygenation Event (GOE) did not occur until 2.3 billion years ago. The putative billion-year discrepancy between oxygenic photosynthesis and the oxygenation of the atmosphere may be explained by the transformation of the planet’s highly reduced marine chemistry to a more oxidized state. Oxygen released by photosynthesis would have been quenched by reacting with elements in their reduced forms for hundreds of millions of years after the evolution of cyanobacteria.
  6. Hello, I'd like to know what is meant by viral turnover in the following context: Rough estimates suggest that the lysis of cells by marine viruses removes 20 to 40 per cent of all of the bacteria every day. This astonishing viral turnover of planktonic microbes fertilizes the water below the sunlit surface of the sea.
  7. Hello, Does any body know what is what are mushroom-growing termites. does it refer to kinde of termites that help in growing mushrooms and fungi as set in one of the websites (Fungus-farming termites (Odontotermes obesus) are able to sniff out weedy, parasitic fungi (Pseudoxylaria) and selectively bury them alive because they smell different than the crops. Fungus-farming termites grow a fungus, Termitomyces, in carbon-dioxide rich environments of their nest mounds.)? Here is the context: A different nutritional strategy has evolved among a group of mushroom-growing termites in Africa and elsewhere in the Old World that use fungi rather than gut protists for cellulose digestion. Termites grow Termitomyces mushrooms on their cellulose-rich faeces in towering mud mounds and eat the resulting compost. From South America to parts of the southern United States, leaf-cutter ants cultivate different kinds of mushrooms in their underground nests. The ants eat special buds that form as swellings on the fungal colony.
  8. what do you mean by random mutation here?
  9. Hello, I am translating a book called Microbiology: A very Short introduction, and I don't understand the meaning of arbitrary measures of genetic novelty in the following context: The application of the term ‘species’ is even more problematic for viruses than bacteria and we rely upon arbitrary measures of genetic novelty when we refer to different kinds of bacteriophage.
  10. What is meant by shed in this context? Mucous membranes are the layers of epithelial cells that line internal organs and form a barrier against the external environment. These membranes secrete mucous in some locations. Microorganisms that become trapped in this sticky fluid are shed from the epithelial surface. does it meant to drop from?
  11. Hello, I'm working on Microbiology: A Very Short Introduction (Very Short Introductions) and I came up with the following sentence which seems unclear to me The induction of cancer is indirect, with the involvement of a specific viral gene (gene X) affecting the expression of genes in the host cells that control cell division. does the second sentence (with the involvement of ...) is an explanation why the induction is indirect? Here is the full context: The link between persistent infection with hepatitis B virus and cancer is clear from epidemiological studies showing that countries where the infection is most prevalent also show a high incidence of liver cancer. When the virus is active it destroys liver cells and causes inflammation. The induction of cancer is indirect, with the involvement of a specific viral gene (gene X) affecting the expression of genes in the host cells that control cell division.
  12. The ubiquity and prevalence of viral genes in the genomes of cellular organisms is a measure of the influence of viruses on the evolution of prokaryotes and eukaryotes and we are only beginning to grapple with the origin of viruses themselves. The science of virology is younger than the field of bacteriology. I think it means to discover or to understand not to face or stand against. Source: A very short introduction to microbiology by Nicolas P money
  13. Hello, I am translating a very short introduction to microbiology by Nicholas P. Money and I don't understand how complement of rna is studied using this technique : This is the context: Millions of copies of each DNA sequence are dotted onto the chip in a specific two-dimensional pattern and the investigator can study which of the genes are being transcribed under a particular set of conditions by adding a labelled solution of the mRNA from a population of cells. The mRNA is labelled with a fluorescent dye, and after this sample has been allowed to react with the microarray, mRNAs bound to the segments are identified from the positions of their complementary genes on the chip. This snapshot of transcription is one of the sources of information used in the study of the entire complement of RNA.
  14. noha

    Microbiology

    what is meant by compromise in the following context, does it mean to hinder? The heat shock response offers another example of the genetic control of cell activity. Heat shock proteins (HSPs) are produced by all organisms when they are stressed by heat and other factors that compromise their biological activities.
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