نتایج جستجو برای: life origin
تعداد نتایج: 932403 فیلتر نتایج به سال:
Chemiosmotic coupling - the harnessing of electrochemical ion gradients across membranes to drive metabolism - is as universally conserved as the genetic code. As argued previously in these pages, such deep conservation suggests that ion gradients arose early in evolution, and might have played a role in the origin of life. Alkaline hydrothermal vents harbour pH gradients of similar polarity an...
The origin of life is one of the most fundamental, but also one of the most difficult problems in science. Despite differences between various proposed scenarios, one common element seems to be the emergence of an autocatalytic set or cycle at some stage. However, there is still disagreement as to how likely it is that such self-sustaining sets could arise “spontaneously”. This disagreement is ...
We discuss some of the cosmological constraints on the evolution and persistence of life in the Universe and in hypothetical universes other than our own. We highlight the role played by the age and size of the universe, and discuss the interplay between the main-sequence stellar lifetime and the biological evolution time scale. The consequences of different versions of the inflationary univers...
The role of carbon in the development of life and as the structural backbone of all organisms is universally accepted and an essential part of evolution. However, the molecular basis is largely unknown and the interactions of carbon with nitrogen and oxygen in space are enigmatic. In 1985, the previously unknown form of carbon, coined fullerene, was discovered. We hypothesize that by virtue of ...
The complexity of life boils down to the definition: "self-sustained chemical system capable of undergoing Darwinian evolution" (Joyce, 1994) [1]. The term "self-sustained" implies a set of chemical reactions capable of harnessing energy from the environment, using it to carry out programmed anabolic and catabolic functions. We briefly present our opinion on the general validity of this definit...
The origin of stable self-replicating molecules represents a fundamental obstacle to the origin of life. The low fidelity of primordial replicators places restrictions on the quantity of information encoded in a primitive nucleic acid alphabet. Further difficulties for the origin of life are the role of drift in small primordial populations, reducing the rate of fixation of superior replicators...
The mica hypothesis is a new hypothesis about how life might have originated. The mica hypothesis provides simple solutions to many basic questions about the origins of life. In the mica hypothesis, the spaces between mica sheets functioned as the earliest cells. These 'cells' between mica sheets are filled with potassium ions, and they provide an environment in which: polymer entropy is low; c...
There are diverse theories about the origin of life on Earth. Perhaps it started with an electric spark that generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia, and hydrogen, and over million years, larger and more complex molecules could form. Other possibility is that molecules of life met on clay due to DNA are relatively well preserved in those conditions...
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