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Explain transcription and translation in protein synthesis.

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Explain transcription and translation in protein synthesis. The transcription stage of protein synthesis. DNA cannot leave the nucleus of a cell, though it plays a fundamental role in the process of protein synthesis. Though DNA doesn't directly get involved with protein synthesis it provides the blueprints, the instructions for the process and thus is considered to be a permanent reference library, holding all the important information required. Because all the important information needed for protein synthesis is locked away in a nucleus of a cell a systems is required which allows for the transfer of the information needed for protein synthesis, from the nucleus to the ribosomes, (held in the cytoplasm of a cell)-to facilitate the production of polypeptide chains and resultantly proteins. Protein synthesis can be looked at in two principle stages a stage named transcription and a stage called translation. For protein synthesis to occur specific information stored in the DNA must be copied into/on an RNA molecule and this process is where the stage of transcription can be seen. Transcription is essentially a process which allows DNA to communicate with the ribosomes in the cytoplasm. The process starts in the nucleus of a cell and begins when the double helical structure of a DNA molecule begins to unwind, this process is facilitated by an enzyme known as DNA helicase, which causes hydrogen bonds between the two DNA polynucleotide strands to break, separating the strands.' ...read more.


not large enough for DNA to pass through- which is just as well because DNA is vital to the continued functioning of a cell/organism and is too valuable to lose from the nucleus. Once in the cytoplasm the mRNA molecule seeks out a ribosome (the protein factories), where the conversion of the information replicated during the transcription stage can occur, (this information will then be used in the production of peptide chain building from the ribosome). As considered the process of translation occurs at the site of a ribosome, which reside in the cytoplasm of a cell. We know that from our basic biology knowledge gained previously that a ribosome is composed of two units, a large subunit and a small subunit and it is the small subunit of a ribosome with which the strand of mRNA binds. mRNA because of its structure (made from one strand of complementary bases in the replication process of transcription), carries specific information in the form of codons (a triplet of nitrogenous bases), which have a corresponding and complementary relationship with amino acids to be used in the protein synthesis. The translation process occurs with the assistance of another form of RNA in the flavour of transfer RNA (tRNA). Perhaps the most crucial property of tRNA is its ability to bind to an amino acid at one of it ends of its molecule and to an mRNA strand at its other end, it is therefore said to possess two functional sites. ...read more.


This process works by, taking the example of the process of translation from above where once a triplet is read and an amino acid delivered the ribosome moves onto the next triplet code, once both tRNA molecules housed in a ribosome have move on, the strand may be read again by subsequent ribosomes queued up behind the previous ribosome. The result of course will be the same polypeptide chain being synthesised seeing as the same coded template is being translated, it is seen as an advantageous process allowing large number of polypeptides to be made from a single mRNA strands in a short space of time. Once a strand has been read it and is finished with it will fragment and breakup allowing for the recycling of the constituent nucleotides. The newly created synthesised polypeptide chain isn't yet a protein at this stage, as it is subject to folding and coiling and the influences of differing forms of bonding, depending upon the particular protein coded for of course will dictate its protein structure and ultimate shape and function. The stage of translation is complete the moment the primary structure, the polypeptide chain detaches from the mRNA strand and the ribosome. The mRNA coded instruction has thus been translated into a primary structure of a protein. Protein synthesis is a continuous ongoing process within the life of a cell. ...read more.

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