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Transcription is the process by which the information contained in a molecule of DNA is transferred to a fragment of mRNA - the messenger RNA. It can be possible due to action of RNA polimerase and transcription factors.
In a short terms, the cell takes in reading out a needed part of its genetic instructions is to copy a particular portion of DNA - a gene - into an RNA sequence. This gene is codified by sequence of nucleotides that will determine the produce of specific proteins.
Moreover, RNA has also a singular property: it can holds catalytic functions - the ribozimes - due to its ability of fold into complex three-dimensional shapes.
During the production of a molecule of mRNA, the hydrogen bridges that connect the chains of the DNA are broken. When this occurs, the nucleosides that will compose mRNA, start to bind in one of the DNA chains. This bind obeys a rigorous pattern of attach between the nitrogenous basis: where in DNA has timine (T), a nucleoside with adenine is bound (A)... the pattern is shown below:
DNA (T) - (A) RNA
DNA (C) - (G) RNA
DNA (G) - (C) RNA
DNA (A) - (U) RNA.
(U) means “uracil”;
(G) means “guanosine”;
(C) means “citosine”.
When the nucleotides attach to DNA chain - that works as model - they are bound for the action of the RNA polimerase. It produces, thus, a RNA chain whose sequence of basis is complementary to sequence of the DNA.
When it is ready, the RNA untie of DNA and undergoes the splicing and the DNA comes back to its double-helix structure.
The fact of RNA to be produced from DNA, allows to deduce which will be its sequence of basis, since that be known the sequence of DNA chain that originated it.
A DNA chain that contains the ATGCTA sequence, for example, will produce a RNA with UACGAU sequence.
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Molecular biology is the branch of biology that focuses on the sub-cellular components and functions of living organisms. The analysis of sub-cellular components, that reponds to physical and chemical states of their structural biomolecules, shows the factors that establish function of the organisms as a whole.
Thus, the study of these components give the basis of all science that related to the life and your relationship with the environment.
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The term "Central Dogma" was coined by Francis Crick, co-discoverer of structure of the DNA.
The Central Dogma of Molecular Biology states that the genetic information of living organisms is encoded in the form of DNA (deoxyribonucleic acid). DNA is synthesized via replication. To synthesize proteins, the DNA must first be transcribed to messenger RNA (ribonucleic acid), which is then translated into protein.
The Central Dogma dictates a one-way flow from DNA to protein. The discovery of retroviruses challenged the Central Dogma when scientists discovered viruses that encoded their genomes as RNA. Upon infection of a host cell, the viral RNA was reverse transcribed into DNA. HIV (human immunodeficiency virus) is a popular example of a retrovirus. So, the central dogma may be extended with "RNA to DNA".
It can be stated in a oversimplified terms, as above, that DNA can be formed by RNA or by it self-replication and this DNA produces RNA that produces proteins. This process can be comprehended in four steps: Transcription, Translation, Replication and Splicing, according to the Molecular Biology of the Cell, by Bruce Alberts and cols.
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The DNA of cell produces three types of different RNA involved in protein synthesis: the messenger RNA (mRNA), the ribossomic RNA (rRNA) and the transfer RNA (tRNA). But only the messenger RNA contains instruction to synthetize proteins. Ribossomic and transfer RNAs, however, are indispensable to protein syntheses.
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In the eukaryotes, the majority of cells, at first, codifies pre-mRNA (a primary transcript). The pre-mRNA is consisted of exons and introns segments, which, reorganized by splicing, form mRNA.
The exons are functional; the not functional (introns) are removed. Thus, all the gene is in a long chain of RNA, that, later, will be reduced and converted into a functional molecule of mRNA.
This processing of the RNA occurs in the nucleus before mRNA being set free for cytoplasm.
The mechanism of alternative splicing makes possible to produce different types of mRNA, depending on what sequences are treated as introns and what remains as exons.
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The creation of a hybrid .
In molecular biology terms, this generally refers to the combination of segments of nucleic acid from different species.
In situ hybridization is a technique involves detection of hundreds of base pairs, in metaphase chromosomes or messenger RNA in individual cells.
Visualization by radioactive pre-labeling of nucleic acid, had now largely been replace by the use of fluorescent labels, ussually conjugated to antibodies which have specific affinity for nucleotide probes, or their "reporter molecules".
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Abbreviation for the technique of Fluorescence In Situ Hybridisation.
Using the Nick Translation reaction to incorporate a biotinylated nucleotide, a probe is prepared from a genomic clone or cDNA clone.
The chromosomes are denatured in a metaphase spread, the probe hybridized, and the site of hybridization located, in situ using streptavidin and fluorescent labeled antibody.
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