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Wyszukujesz frazę "RNA world" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
New face of the “RNA world”
Autorzy:
Tyczewska, Agata
Figlerowicz, Marek
Tematy:
non-coding RNA
small regulatory RNA
gene expression
RNA world
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/703400.pdf  Link otwiera się w nowym oknie
Opis:
For a very long time, RNA was considered just the medium by which information flows from DNA into the cell. The model proposed in the 1960s assumed that proteins are the main products and regulators of the gene expression process. In this context, the results of the Human Genome Project and the discoveries of RNA interference and small regulatory RNAs (srRNAs) came as a true surprise. The first ones demonstrated that less than 5% of the human genome encodes proteins. The second showed that RNA, especially 20-30 nt-long molecules should be placed among the most important factors controlling gene expression. srRNAs are capable of affecting the release and flow of genetic information in many different ways. They can induce changes in the genome structure, inhibit transcription, mediate mRNA degradation and repress translation. Interestingly, in different organisms, different pathways are used to regulate gene expression. It has recently been estimated that, in humans, the expression of 35-40% of genes is controlled by srRNA. As a result, RNA is currently believed to be a central molecule in many biological processes.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The old and new RNA world
Autorzy:
Szweykowska-Kulinska, Z.
Tematy:
Earth
RNA world hypothesis
life
ribozyme
small RNA
long noncoding RNA
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Wydawca:
Polskie Towarzystwo Botaniczne
Powiązania:
https://bibliotekanauki.pl/articles/57730.pdf  Link otwiera się w nowym oknie
Opis:
Among the numerous hypotheses offering a scenario for the origin of life on Earth, the one called “The RNA World” has gained the most attention. According to this hypothesis RNA acted as a genetic information storage material, as a catalyst of all metabolic reactions, and as a regulator of all processes in the primordial world. Various experiments show that RNA molecules could have been synthesized abiotically, with the potential to mediate a whole repertoire of metabolic reactions. Ribozymes carrying out aminoacyl-tRNA reactions have been found in SELEX (systematic evolution of ligands by exponential enrichment) approaches and the development of a ribosome from a RNA-built protoribosome is easy to imagine. Transfer RNA aminoacylation, protoribosome origin, and the availability of amino acids on early Earth allowed the genetic code to evolve. Encoded proteins most likely stabilized RNA molecules and were able to create channels across membranes. In the modern cell, DNA replaced RNA as the main depositor of genetic information and proteins carry out almost all metabolic reactions. However, RNA is still playing versatile, crucial roles in the cell. Apart from its classical functions in the cell, a huge small RNA world is controlling gene expression, chromatin condensation, response to environmental cues, and protecting the cell against the invasion of various nucleic acids forms. Long non-coding RNAs act as crucial gene expression regulators. Riboswitches act at the level of transcription, splicing or translation and mediate feedback regulation on biosynthesis and transport of the ligand they sense. Alternative splicing generates genetic variability and increases the protein repertoire in response to developmental or environmental changes. All these regulatory functions are essential in shaping cell plasticity in the changing milieu. Recent discoveries of new, unexpected and important functions of RNA molecules support the hypothesis that we live in a New RNA World.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modelling of molecule evolution in protocells
Autorzy:
Myszor, D.
Cyran, K. A.
Tematy:
RNA world
protocell
mathematical model
protokomórka
model matematyczny
Pokaż więcej
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/330879.pdf  Link otwiera się w nowym oknie
Opis:
In this article, we analyse the process of the emergence of RNA polynucleotides located in an enclosed environment, at an early stage of the RNA world. Therefore we prepared a mathematical model, composed of a set of differential equations, which simulates the behaviour of an early biological system bounded by a protocell membrane. There is evidence that enclosed environments were available on the primordial Earth. There are also experimental proofs that RNA strands can develop in these formations. The proposed model allows analysis of the influence of membrane permeability on the composition of internal material. It takes into account phenomena that lead to the elongation of an RNA strand (ligation), fission of molecules (phosphodiester bond breakage) and replication of polynucleotides. Results obtained from the model point out that the existence of protocells might support concentration of material and creation of longer molecules.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The origin of life on Earth and the hypothesis of panspermia
Powstanie życia na Ziemi a hipoteza panspermii
Autorzy:
Kucharski, Jerzy
Opis:
This is an overview of hypotheses (or theories) about the origin of organisms on Earth, or the possibility of sifting through life from other cosmic bodies. From Old Greek thought to the latest discoveries related to the development of life as well as possible migration. This is not a proof of self-actualization, but I present the possible paths of its development or on our planet, such as the possibility of space aliens coming to Earth and its habitation. Beginning with the abiogenesis, ending with a modified version of it - the emergence of chemical compounds of organic compounds and the possibility of their development into the first primitive organisms.
Jest to przegląd hipotez (lub teorii) na temat powstania organizmów na Ziemi lub też możliwości zasiania życia z innych ciał kosmicznych. Od myśli starogreckiej do najnowszych odkryć związanych z rozwojem życia jak i też możliwą migracją. Nie jest to dowód na powstanie samoczynnie życia, ale przedstawiam możliwe drogi jego rozwoju czy na naszej planecie, tak jak możliwości przybycia na Ziemię organizmów z kosmosu i jej zasiedlenie. Zaczynając od samorództwa, kończąc na zmodyfikowanej jego wersji – powstania ze związków chemicznych związków organicznych i możliwości ich rozwoju w pierwsze prymitywne organizmy.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
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    Wyświetlanie 1-4 z 4

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