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An overview of protein synthesis.
Within the nucleus of the cell (light blue), genes (DNA, dark blue) are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA (red) that is then transported out of the nucleus and into the cytoplasm (peach), where it undergoes translation into a protein. mRNA is translated by ribosomes (purple) that match the three-base codons of the mRNA to the three-base anti-codons of the appropriate tRNA. Newly synthesized proteins (black) are often further modified, such as by binding to an effector molecule (orange), to become fully active.

Protein biosynthesis is the process in which cells build proteins. The term is sometimes used to refer only to protein translation, but more often it refers to a multi-step process, beginning with transcription and ending with protein translation.

1 Transcription

Main article: Transcription

Transcription only requires one strand of the DNA double helix. This is called the coding strand. The transcription starts with initiation. RNA polymerase, an enzyme, binds to a specific region on the DNA, marking the starting point, called the promoterIn genetics, a promoter is a DNA sequence that enables a gene to be transcribed. The promoter is recognized by RNA polymerase, which then initiates transcription. The perfect promoter is called a canonical sequence. Promoter elements Core promoter Transcr. As the RNA polymerase binds on to the promoter, the DNA strands are beginning to unwind.

As the RNA polymerase travels through the strand that is opposite to the coding strand (the cell wants a copy of the coding strand, so it needs to copy that from the DNA that is the opposite of the coding strand), it matches corresponding mRNA nucleotides to the DNA. The mRNA is elongated as the polymerase proceeds. This process is known as elongationElongation is an astronomical term that refers to the angle between the Sun and a planet, as viewed from Earth. When an inferior planet is visible after sunset, it is near its greatest eastern elongation . When an inferior planet is visible before sunrise.

As the polymerase reaches the termination, modifications are required for the newly transcribed mRNA to be able to travel to the other parts of the cell, including cytoplasm and ERThe endoplasmic reticulum or ER (endoplasmic means "within the cytoplasm", reticulum means "little net") is an organelle found in all eukaryotic cells. The ER modifies proteins, makes macromolecules, and transfers substances throughout the cell. Prokaryot. A 5’ cap is added to the mRNA to protect it from degradation. A poly-A tail is added on the 3’ end for protection and as a template for further process.

2 Translation

Main article: Translation

During translation, the message of mRNA is decoded to make proteins. Translation includes initiation, elongation, translocation , and termination. Initiation and elongation occur when the ribosome recognizes the starting codon on the mRNA strand and binds to it. The ribosome has sites, which allow another enzyme, tRNA to bind to the mRNA. On tRNA, there is an anticodon that is used to match the codon on the mRNA. tRNA also has a single unit of amino acid attached to it.

As the ribosome travels down the mRNA one codon at a time, another tRNA is attached to the mRNA at one of the ribosome site. The first tRNA is released, but the amino acid that is attached to the first tRNA is now moved to the second tRNA, and binds to its amino acid. This translocation continues on, and a long chain of amino acid (protein), is formed.

When the entire unit reaches the end codon on the mRNA, it falls apart and a newly formed protein is released. This is the termination.

It is important to know that during this process, many enzymes are used to either assist or facilitate the whole procedure.

3 Events following biosynthesis

The events following biosynthesis include protein folding and post-translational modification. During and after it synthesis, polypeptide chains often fold to assume, so called, native secondary and tertiary structures. This is known as protein folding.

Many proteins undergo post-translational modification. This is may include the formation of disulfide bridges or attachment of any of a number of biochemical functional groups, such as acetate, phosphate, various lipids and carbohydrates. Enzymes may also remove one or more amino acids from the leading (amino) end of the polypeptide chain, leaving a protein consisting of two polypeptide chains connected by disulfide bonds.

4 See also

5 External links

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Topics: Protein Biosynthesis, Transcription, Translation, Events...

Proteinmyoglobin, showing coloured alpha helices. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry. A protein is a complex,	Protein biosynthesisnucleus of the cell light blue , genes (DNA, dark blue are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA red that is then transported out of the nucleus and into the cytoplasm p	Protein kinaseA protein kinase is an enzyme that can transfer a phosphate group from a donor molecule (usually ATP) to an amino acid residue of a protein. The protein kinase mechanism is used in signal transduction for the regulation of enzymes: phosphorylation can act
Protein phosphataseProtein phosphatases are enzymes that remove phosphate groups that have been attached to amino acid residues of proteins by protein kinases. The phosphates are important in signal transduction by regulating the proteins they are attached to. To reverse th	Protein targetingProtein targeting includes the mechanisms by which a biological cell transports proteins to the appropriate organelle for insertion into a membrane or secretion to the outside. This article deals with protein targeting in eukaryotes except as noted. Prote	ProteinoidProteinoids are protein-like molecules formed inorganically from amino acids. Some theories of abiogenesis propose that proteinoids were a precursor to the first living cells. The inorganic polymerization of amino acids into proteins through the formation
Protein folding	Protein Data Bank	Proteinuria
Protein catabolism	Protein engineering	Protein sequencer
Protein (band)	Protein structure prediction	Protein subunit

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