Protein biosynthesis

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Protein biosynthesis

Protein synthesis is the process in which cells

Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
build protein

Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
s. The term is sometimes used to refer only to protein translation

Translation (genetics)

Translation is the first stage of protein biosynthesis . Translation is the production of proteins by decoding mRNA produced in Transcription ....
but more often it refers to a multi-step process, beginning with amino acid synthesis

Amino acid synthesis

For the non-biological synthesis of amino acids see: Strecker amino acid synthesisAmino acid synthesis is the set of biochemical processes by which the various amino acids are produced from other compounds....
and transcription

Transcription (genetics)

Transcription is the synthesis of RNA under the direction of DNA. RNA synthesis, or transcription, is the process of transcribing DNA nucleotide sequence information into RNA sequence information....
which are then used for translation. Protein biosynthesis, although very similar, is different for prokaryote

Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus....
s and eukaryote

Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
s.

Amino acid synthesis
Amino acids are the monomers which are polymerized to produce proteins.

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Encyclopedia

Protein synthesis is the process in which cells

Cell (biology)

Protein

Translation (genetics)

Amino acid synthesis

Transcription (genetics)

Transcription is the synthesis of RNA under the direction of DNA. RNA synthesis, or transcription, is the process of transcribing DNA nucleotide sequence information into RNA sequence information....
which are then used for translation. Protein biosynthesis, although very similar, is different for prokaryote

Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus....
s and eukaryote

Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
s.

Amino acid synthesis

Amino acids are the monomers which are polymerized to produce proteins. Amino acid synthesis is the set of biochemical processes (metabolic pathways) which build the amino acids from carbon sources like glucose

Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
. Not all amino acids may be synthesised by every organism, for example adult humans have to obtain 8 of the 20 amino acids from their diet.

Transcription

Transcription is the process by which an mRNA template, encoding the sequence of the protein in the form of a trinucleotide code

Genetic code

The genetic code is the set of rules by which information encoded in genetic material is Translation into proteins by living cell s. The code defines a mapping between tri-nucleotide sequences, called codons, and amino acids....
, is transcribed from the genome

Genome

In classical genetics, the genome of a diploid organism including eukarya refers to a full set of chromosomes or genes in a gamete; thereby, a regular somatic cell contains two full sets of genomes....
to provide a template for translation. Transcription copies the template from one strand of the DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
double helix, called the template strand.

Transcription can be divided into 3 stages: Initiation, Elongation and Termination, each regulated by a large number of proteins such as transcription factor

Transcription factor

In the field of molecular biology, a transcription factor is a protein that binds to specific DNA sequence and thereby controls the transfer of genetic information from DNA to RNA....
s and coactivators that ensure the correct gene is transcribed in response to appropriate signals.

The DNA strand is read in the 3' to 5' direction and the mRNA is transcribed in the 5' to 3' direction by the RNA polymerase

RNA polymerase

RNA polymerase is an enzyme that produces RNA. In cell s, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called Transcription ....
.

Translation

The synthesis of proteins is known as translation. Translation occurs in the cytoplasm

Cytoplasm

The cytoplasm is the part of a Cell that is enclosed within the plasma membrane. In eukaryote cells the cytoplasm contains organelles, such as mitochondrion, that are filled with liquid kept separate from the rest of the cytoplasm by biological membranes....
where the ribosome

Ribosome

Ribosomes are complexes of RNA and protein that are found in all cell s. Ribosomes from bacteria, archaea and eukaryotes, the three domains of life on Earth, have significantly different structure and RNA....
s are located. Ribosomes are made of a small and large subunit which surrounds the mRNA. In translation, messenger RNA (mRNA) is decoded to produce a specific polypeptide according to the rules specified by the genetic code

Genetic code

Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s that form a protein. Translation is necessarily preceded by transcription

Transcription (genetics)

Transcription is the synthesis of RNA under the direction of DNA. RNA synthesis, or transcription, is the process of transcribing DNA nucleotide sequence information into RNA sequence information....
. Translation proceeds in four phases: activation, initiation, elongation and termination (all describing the growth of the amino acid chain, or polypeptide that is the product of translation).

In activation, the correct amino acid (AA) is joined to the correct transfer RNA (tRNA). While this is not technically a step in translation, it is required for translation to proceed. The AA is joined by its carboxyl group to the 3' OH of the tRNA by an ester bond. When the tRNA has an amino acid linked to it, it is termed "charged". Initiation involves the small subunit of the ribosome binding to 5' end of mRNA with the help of initiation factors (IF), other proteins that assist the process. Elongation occurs when the next aminoacyl-tRNA (charged tRNA) in line binds to the ribosome along with GTP and an elongation factor. Termination of the polypeptide happens when the A site of the ribosome faces a stop codon (UAA, UAG, or UGA). When this happens, no tRNA can recognize it, but releasing factor

Release factor

The release factor is a protein that recognizes the termination codon or stop codon in a mRNA sequence on the ribosome.The function of prokaryotic release factors and eukaryotic release factors involve different proteins but have many similarities....
can recognize nonsense codons and causes the release of the polypeptide chain. The capacity of disabling or inhibiting translation in protein biosynthesis is used by antibiotic

Antibiotic

In common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria. Antibiotics belong to the group of antimicrobial compounds used to treat infections caused by microorganisms, including fungus and protozoa....
s such as: anisomycin

Anisomycin

Anisomycin, also known as flagecidin is an antibiotic produced by Streptomyces griseolus which inhibits translation . Partial Enzyme inhibitor of DNA synthesis occurs at anisomycin concentrations that effect 95% inhibition of protein synthesis....
, cycloheximide

Cycloheximide

Cycloheximide is an Enzyme inhibitor of protein biosynthesis in Eukaryote organisms, produced by the bacterium Streptomyces griseus. Cycloheximide exerts its effect by interfering with the translocation step in protein synthesis thus blocking Translation ....
, chloramphenicol

Chloramphenicol

Chloramphenicol is a bacteriostatic antimicrobial originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949....
, tetracycline

Tetracycline

Tetracycline is a broad-spectrum polyketide antibiotic produced by the Streptomyces genus of Actinobacteria, indicated for use against many bacterial infections....
, streptomycin

Streptomycin

Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis....
, erythromycin

Erythromycin

Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins....
, puromycin

Puromycin

Puromycin is an antibiotic that is a potent inhibitor of translation ....
etc.

Events following protein translation

The events following biosynthesis include post-translational modification and protein folding

Protein folding

Protein folding is the physical process by which a polypeptide folds into its characteristic and functional protein structure.Each protein begins as a polypeptide, translated from a sequence of mRNA as a linear chain of amino acids....
. During and after synthesis, polypeptide chains often fold to assume, so called, native secondary

Secondary structure

In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids ....
and tertiary structure

Tertiary structure

In biochemistry and chemistry, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates....
s. This is known as protein folding
Protein folding

Protein folding is the physical process by which a polypeptide folds into its characteristic and functional protein structure.Each protein begins as a polypeptide, translated from a sequence of mRNA as a linear chain of amino acids....
.

Many proteins undergo post-translational modification. This may include the formation of disulfide bridges or attachment of any of a number of biochemical functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
s, such as acetate

Acetate

An acetate, or ethanoate, is either a salt or ester of acetic acid.In chemistry, the abbreviation Ac refers to the acetyl group. The anion and the functional group may be written as -OAc and AcO-, or OAc respectively....
, phosphate

Phosphate

A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry....
, various lipid

Lipid

Lipids are broadly defined as any fat-soluble , naturally-occurring molecule, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others....
s and carbohydrate

Carbohydrate

Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components ....
s. Enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s 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.

External links

Section of The Cell: A Molecular Approach by Geoffrey M. Cooper
For high school
Wesleyan University Learning Objects animation of protein synthesis.
From at the Niels Bohr Institute.
From RNA to Protein Synthesis .

Protein biosynthesis

Amino acid synthesis

Transcription

Translation

Events following protein translation

See also

External links