Transcription
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The first step of protein synthesis is called <b>transcription</b>. The DNA transcription to mRNA is actually the first step of the protein synthesis. During the transcription step the instructions encoded in the DNA of the genes are transcribed into the nucleotide sequence code of a ribonucleic acid (RNA). Because this RNA molecule carries the protein synthesis instructions, or in other words a “message”, from the genes to the ribosomes, it is called messenger RNA (abbreviated as mRNA).</p>
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The second step of protein synthesis is <b>mRNA Translation (or just Translation).</b> The mRNA Translation step follows right after the first step of protein synthesis called DNA Transcription (or just Transcription). During the transcription, the information encoded in the DNA is copied to a messenger RNA sequence (mRNA), which then can move through the nucleus membrane and can reach the ribosomes in the cytoplasm. The production of proteins happens during the second step of protein synthesis process – the Translation. Sometimes protein synthesis process is referred only to Translation step, because no actual protein synthesis happens during the Transcription. However transcription is responsible for moving the genetic instructions from the nucleus to the cytoplasm, where the DNA/RNA code is translated by the ribosomes to a polypeptide sequence, which will later be folded into a protein.</p>
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The translation process requires the involvement of three different types of RNA molecules, each having it’s own function:</p>
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<b>messenger RNA (mRNA)</b> which acts as a “middle-man” or “messenger” between the DNA which caries the genetic material and the protein production workshops (the ribosomes) which reside in the cytoplasm.
different<b> ribosome RNA (rRNA)</b> molecules which participate in the formation of the ribosome sub-units
multiple <b>transport RNA (tRNA)</b> molecules for each individual amino-acid residue--there is also a pre-mRNA which predates the processed RNA full of Introns --in Eukaryotes not in Prokaryotes
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The <b>Pribnow box (also known as the Pribnow-Schaller box)</b> is the sequence <b>TATAAT</b> of six nucleotides (thymine-adenine-thymine-etc.) that is an essential part of a promoter site on DNA for transcription to occur in bacteria.It is an idealized or consensus sequence—that is, it shows the most frequently occurring base at each position in a large number of promoters analyzed; individual promoters often vary from the consensus at one or more positions. It is also commonly called the -10 sequence, because it is centered roughly 10 base pairs upstream from the site of initiation of transcription.</p>
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The <b>Pribnow box has a function similar to the TATA</b> box that occurs in promoters in eukaryotes and archaea: it is recognized and bound by a subunit of RNA polymerase during initiation of transcription. This region of the DNA is also the first place where base pairs separate during prokaryotic transcription to allow access to the template strand. The AT-richness is important to allow this separation, since adenine and thymine are easier to break apart (not due to the hydrogen bond count
It is named after David Pribnow and Heinz Schaller.</p>
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