Genetic information sharing in bacteria

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What do we see in a bacterial cell with an electron microscope and a super-resolution microscope?

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Bacteria are called "bag of enzymes" due to the lack of specific properties of bacterial cell and blood cells. In other words, only a pouch filled with enzymes. But for the past few decades, biologists have been blown away by the microscopic apparatus, and they have been blown away by the specialty of the Kaviguru's mythology. Some new gemstones have been thrown out, in which the bacterial cell of brightness has glimpsed. Scientists have begun to understand that complex biochemistry is still running in the bacteria and bacterial atoms. This has led to the new ideas about the biology of bacteriology. So is the biology, exchange of genetic information, this story.

One-way flow of information: DNA → RNA → Protein

In the beginning, the reader may raise the question, what exactly do we mean by "genetic information"? We know that the structural and functional units of the organism are "cells". Here we identify genetic information in cell structure, work, and evolution. This genetic information is stored in Dyxerobonucleic Acid or DNA in short. But according to this data, all the functioning of the cell performs Protein Molecule. Genetic data is transmitted from RNA to ribonucleic acid (RNA), then RNA from DNA. Except for some exceptions, this one-way flow of genetic information is true throughout biology. This is called "Central Dogma of Molecular Biology".

The information flow from this DNA to RNA is in two steps.

1. Transcription - DNA and RNA are both nucleic acids. Genetic data is transmitted from one nucleic acid to another nucleic acid in the first phase of torrents [1]. This step is the transcription or transcription.

2. Translation - Protein is not made with nucleic acids, but the protein unit of protein is amino acids. [1] Each word-per-protein protein contains amino acids. In the second phase of torrents, genetic information from nucleic acids (RNA) is transmitted in the language of amino acids. This step is translation or translation.

When two steps were recognized separately

Scientist Francis Crick, whom many of us know as DNA's inventor of double helix composition, proposed in 1958 an article "The Basis of atomic Biology" about the exchange of genetic information in [2]. However, a clear idea about two streams of torrent and their identity is not found in that article. The first focus was on this in 1961, the breakthrough study of scientist François Jakob and Jacques Mono [3]. Jacob-Mono proposed that genetic information flow from proteins in DNA is done by a chemical intermediate or chemical medium. In this chemical medium, they name the messenger as "informational". In modern biology, Messenger (Messenger) is called RNA or mRNA [4].

Genetic data is transmitted from DNA to RNA, and then from RNA to proteins. That's the fundamental doctrine of molecular biology.

Here are two steps for "Transcription" and "Translation" - "The Basics of Molecular Biology". It is necessary to say that RNA is generated from DNA, the inventor of that information but not Jacob-Mono. This discovery has already happened. In 1956, why did Valkin and Larry Ostrichen first notice that when the virus infected a bacterium, some new RNAs were formed from the virus's DNA in the bacteria [5]. However, this was not known when the RNA was the intermediate medium of DNA and protein on the path of genetic torrents. As the claimant of that achievement, but the names of Jacob and Mano will remain.

But what happens to the bacteria

In the flow of genetic information, what is the structure of the cell, it plays a very important role. Because, the genetic data-rich DNA is in the center of the cell nucleus. The whole organism surrounding this nucleus has been divided into two parts: "Prokaryote" and "Eukaryote" or can be thought of in this way, primitive and modern. In "eukaryotic cells", this DNA-containing nucleus is in a screen. The screen separates the nucleus from the remaining components of the cell. But this screen is missing for "prokaryotic cell" or "original cell". Bacteria fall into this "prokaryotes" group.

Cell screen has significant significance in exchange of information in cells. The first of two phases of data flow in eukaryotic cells, ie transcription, is either in the nucleus behind the screen. When the RNA of the DNA is completed in the nucleus (figure 1.A), the RNA comes out of the nucleus screen. Protein (Figure 1.B) is produced from this RNA with the help of original translator or translation machine ribosome in cytoplasm outside the nucleus. The prokaryotic group bacteria does not have the screen of this nucleus. Does the bacteria take place two stages of torrential activity in the same place?

       Genetic torrent: (A) Phase I: Transcription or transcription. The main factor for replication is RNA polymerase 
     (RNAP) that creates RNA from DNA. (B) Second Phase: Translation or Translation. Protein is produced from RNA 
   through the translation machine ribosome. (c) Cartoon of co-transcriptional translation and (D) Millennium and his 
     colleagues' co-transcriptional translation's experimental evidence.

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Almost half a century ago, a similar proposal was made by biologist Gunda Stent. In an article in "Science" in 1964, while discussing the research of Jacob-Mono, he said that there is a correlation between translation between transcription in bacteria [6]. Protein preparation begins with incomplete mRNA during transcription, without having to separate the two stages. It is possible for the absence of the nucleus screen in the bacteria. This suggestion is derived from the word co-transcriptional translation. But to prove it, it is necessary to peep into the bacteria.

Want electron microscope

General microscope is not of special value in bacterial cells, because the bacteria in the form are very small. Bacterial size is usually between 500 to 5000 nanometers (1 nanometer = 10 -9 m). The general microscope is used in the "visible" radiation. For the extent of the length of the wavelength, "visible" light can not be seen in any formative structure smaller than 200 nanometers. So, if the bacteria can be seen through a common microscope, their inner structure is beyond reach.

Electron Microscope is the main tool for evaluating bacterial structure. For the small wavelength of "electron", the electron microscope discovered in 1931 can be found to produce approximately 1 nanometer size.

Proof in hand

With the help of this electron microscope, the first experimental evidence of transcription and translation of bacterial mutations is found. Some scientists at the Harvard Medical School in 1970 used the electron microscope to see the exchange of genetic information inside the bacteria [7]. Some of the bacteria they use for this test are cell walls whose fragments are very fragile. E. Some "mutant" bacteria were created by some genetic changes in coli bacteria, Whose cell walls are more fragile than normal. When these bacteria are mixed in water very quickly, the bacterial material breaks out cell wall and cell walls by pressing the conjunctive pressure of the cell. Scientists Oscar Miller and his colleagues photographed photosynthesis with the help of electron microscope, which provides some of the fancy and invaluable information about the exchange of genetic information in bacteria.

These pictures show that almost all mRNAs are associated with genetic DNA. More pictures also show that every mRNA contains only 20 nanometers in size (Figure 1.D). These particles are actually cell translator, ribosome.

We know today that one can build multiple rhizomes together from a mRNA. The polymerum (Figure 1.C) tells this set of multiple rhubozes with mRNA. Pictures of Miller and his colleagues are the first evidence of the existence of this polyisome (Figure 1.D). But apart from this, a feature of the pictures plays a very important role in establishing relationships between the two stages of gene-data-flow. In photos of electron microscope, there is no polyisomic picture cut off from the genes - the last DNA !!

All translations of bacteria are transcribed during transcription.

What happens to the isolated polygenom from the genetic DNA? That means, we used to see a complete mRNA and protein from which multiple ribosomes. "Complete" mRNA means a mRNA that has been transmitted to the genes. If translation and transcription procedures were done independently of each other, then surely there would be some isolated polysomes.

But it did not match. The absence of isolated polymomes in photos taken in electron microscope proves that protein synthesis from mRNA in bacteria is always during transcription. Dr. Miller and his colleagues say " all translations are during transcription" . So, there is not only correlation between bacteria in the two stages of information flow, but the phases are interconnected with each other. Miller and his colleagues who have studied these images can be said to be the visual evidence for the accuracy of Trent's suggestion.

     Difference between the two-phase flow of information in prokaryotic and eukaryotic cells.

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So what happened?

It was found, apart from structural differences, there is also biological activity between "prokaryotes" (without nucleus screen) and "eukaryotes" (nucleus screen). Significantly, the possibility of functional differences has been created from structural differences here.

Immediate translation of the mRNA does not begin immediately after the mRNA production is completed in the eukaryotic cells under the nucleus screen. The mRNA, which is made from the newly replicated process, is called the nascent RNA. Enhanced mRNA from this nascent RNA is generated through post-transcriptional processing after transcription. Translation possible from this matrimonial mRNA

The condition of this "nascent RNA" is absent in the bacteria. Prior to the completion of mRNA, new protein synthesis begins with "co-transcriptional translation" from the incomplete mRNA during transcription. But what is the significance of this trend? That discussion is in the next part.

Before concluding, Dr. Miller and his colleagues see this decision as "all translations are in transitional period". There is a possibility of transcription from the incomplete mRNA during the transcription, it is one thing to say. But in the bacteria "All translations are in transcription", this decision gives a final black-and-white dimension to the difference between bacteria and eukaryotes. Because, all transcription transcriptions in eukaryotic cells begin after the completion.

The question is, a decision that was made in the 1970s could have passed the real time test? Or did scientists find their fault in a while? We will enter that discussion in the next phase of writing. Over time, this decision and its significance will be welded by the continuous and evolving science research. However, it can be said that the uninterrupted link between the gene and the protein together with the absence of the nuclei screen absence, it was left in the 70's in the scientific field.

(Will continue)

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References and other chunks:

[1] The genetic information that is written in the language is a single "nucleotide" (Nucleotide). Three nucleotides are made up of a 'codon'. Similar words are created around the characters, as well. A genetic message is produced by a number of code encoded in sequence, just as a word is made in order of sequence.

[2] Francis Crick, On Protein Synthesis, Symp Soc Exp Biol. 1958;12:138-63

[3] François Jacob and Jacques Monod, On the Regulation of Gene Activity, Cold Spring Harb Symp Quant Biol. 1961. 26: 193-211

[4] Apart from mRNA there are some other types of RNA types. There will be discussions on this topic in the next episode.

[5] Elliot Volkin, L. Astrachan, Phosphorus incorporation in Escherichia coli ribonucleic acid after infection with bacteriophage T2, Virology 2(2):149-161

[6] Gunther S. Stent, The Operon: On its third anniversary, Science 144(3620):816-20

[7] Miller, O.L., Hamkalo, B.A., and Thomas, C.A., Visualization of bacterial genes in action,  Science 169(3943):392-5