Protein: Difference between revisions
imported>Michael Hardy No edit summary |
imported>Christopher M. Worsham (expansion of several sections) |
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'''Protein''' molecules are chains of [[amino | '''Protein''' molecules are chains of [[Amino acid|amino acids]] that play many important roles in [[Life|living systems]]. As far as is known, proteins have existed as long as life on earth has existed and are an essential ingredient in all cells. For most [[organism|organisms]], including humans, proteins must be digested in order to obtain [[amino acid|essential nutrients]] that cannot be synthesized by the organism. | ||
== | ==Synthesis== | ||
: ''Main Article: [[Ribosome]]'' | |||
In both [[eukaryotic]] and [[prokaryotic]] [[cell (biology)|cells]], proteins are manufactured in [[ribosomes]], which are made up of two sub-units of specially folded strands of [[RNA]] as well as some small proteins. A eukaryotic ribosome (e.g., that of a human) is slightly larger than the prokaryotic ribosome (e.g., that of a bacterial cell), but the two perform essentially the same essential function. Ribosomes connect amino acids to each other via [[peptide bond|peptide bonds]] in order to form strings called [[polypeptides]]. | |||
== | ==Structure== | ||
The sequence of amino acids is determined by the [[genetic code]] on [[DNA]]; the simple sequence of amino acids alone is referred to as a protein's ''primary structure.'' Different residual groups on the amino acids can interact with water or each other, sometimes linking to each other, forming a certain three-dimensional structure, such as an [[alpha helix]] or a [[beta sheet]]; localized three-dimensional structure is referred to as a protein's ''secondary structure''. A protein's ''tertiary structure'' is the entire three-dimensional conformation of a given peptide. ''Quaternary structure'' exists in proteins that are made up of multiple peptides, and it is the entire three-dimensional structure of every peptide and the links between them. | |||
== | ==Function== | ||
Proteins are used within organisms for an extremely vast array of functions, which include but are not limited to structure, sending and receiving messages, regulation of processes, and [[enzyme|enzymes]] are proteins [[catalysis|catalyze]] [[chemical reaction|chemical reactions]]. | |||
===In the diet=== | ===In the diet=== | ||
===As toxins and poisons=== | ===As toxins and poisons=== | ||
===As a record of evolution=== | ===As a record of evolution=== | ||
==References== | ==References== | ||
==See Also== | |||
*[[Amino acid]] | |||
==External links== | ==External links== | ||
[[Category:Biology Workgroup]] | [[Category:Biology Workgroup]] | ||
[[Category:Chemistry Workgroup]] | [[Category:Chemistry Workgroup]] | ||
Revision as of 12:44, 27 June 2007
Protein molecules are chains of amino acids that play many important roles in living systems. As far as is known, proteins have existed as long as life on earth has existed and are an essential ingredient in all cells. For most organisms, including humans, proteins must be digested in order to obtain essential nutrients that cannot be synthesized by the organism.
Synthesis
- Main Article: Ribosome
In both eukaryotic and prokaryotic cells, proteins are manufactured in ribosomes, which are made up of two sub-units of specially folded strands of RNA as well as some small proteins. A eukaryotic ribosome (e.g., that of a human) is slightly larger than the prokaryotic ribosome (e.g., that of a bacterial cell), but the two perform essentially the same essential function. Ribosomes connect amino acids to each other via peptide bonds in order to form strings called polypeptides.
Structure
The sequence of amino acids is determined by the genetic code on DNA; the simple sequence of amino acids alone is referred to as a protein's primary structure. Different residual groups on the amino acids can interact with water or each other, sometimes linking to each other, forming a certain three-dimensional structure, such as an alpha helix or a beta sheet; localized three-dimensional structure is referred to as a protein's secondary structure. A protein's tertiary structure is the entire three-dimensional conformation of a given peptide. Quaternary structure exists in proteins that are made up of multiple peptides, and it is the entire three-dimensional structure of every peptide and the links between them.
Function
Proteins are used within organisms for an extremely vast array of functions, which include but are not limited to structure, sending and receiving messages, regulation of processes, and enzymes are proteins catalyze chemical reactions.