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-{{for|the scientific journal|Macromolecules (journal)}}
-[[Image:ProteinStructure.jpg|thumb|300px|Chemical structure of a [[polypeptide]] macromolecule]]A '''macromolecule''' is a very large [[molecule]] commonly created by [[polymerization]] of smaller subunits ([[monomers]]). They are typically composed of thousands or more [[atoms]]. The most common macromolecules in [[biochemistry]] are [[biopolymers]] ([[nucleic acid]]s, [[protein]]s, [[carbohydrate]]s and [[polyphenols]]) and large non-polymeric molecules (such as [[lipid]]s and [[macrocycles]]).<ref name="Stryer_2002">{{cite book |author= Stryer L, Berg JM, Tymoczko JL | title = Biochemistry | publisher = W.H. Freeman | location = San Francisco | year = 2002 | edition = 5th | isbn = 0-7167-4955-6 | url = http://www.ncbi.nlm.nih.gov/books/NBK21154/ }}</ref> Synthetic macromolecules include common [[plastics]] and [[Synthetic fiber|synthetic fibres]] as well as experimental materials such as [[carbon nanotubes]].<ref>[http://www.americanchemistry.com/s_plastics/doc.asp?CID=1571&DID=5972 Life cycle of a plastic product]. Americanchemistry.com. Retrieved on 2011-07-01.</ref><ref>{{cite journal |last1=Gullapalli |first1=S. |last2=Wong |first2=M.S. |year=2011 |title=Nanotechnology: A Guide to Nano-Objects |url=http://www.aiche.org/uploadedFiles/Publications/CEPMagazine/051128_public.pdf |journal=Chemical Engineering Progress |volume=107 |issue=5 |pages=28–32}}</ref>
-==Definition==
-{{Quote box
- |title = IUPAC definition
- |quote = '''Macromolecule'''<br/>'''Polymer molecule'''
-A molecule of high relative molecular mass, the structure of which essentially<br/>comprises the multiple repetition of units derived, actually or conceptually, from<br/>molecules of low relative molecular mass.
-;Notes
-. In many cases, especially for synthetic polymers, a molecule can be regarded<br/>as having a high relative molecular mass if the addition or removal of one or a<br/>few of the units has a negligible effect on the molecular properties. This statement<br/>fails in the case of certain macromolecules for which the properties may be<br/>critically dependent on fine details of the molecular structure.<br/>
-. If a part or the whole of the molecule fits into this definition, it may be described<br/>as either ''macromolecular'' or ''polymeric'', or by ''polymer'' used adjectivally.<ref>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|date=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|url=http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.pdf}}</ref>
-}}
-The term ''macromolecule'' (''[[wikt:macro-#Prefix|macro-]]'' + ''molecule'') was coined by [[Nobel Prize|Nobel laureate]] [[Hermann Staudinger]] in the 1920s, although his first relevant publication on this field only mentions ''high molecular compounds'' (in excess of 1,000 atoms).<ref>{{cite journal|author=Staudinger, H.; Fritschi, J. |title=Über Isopren und Kautschuk. 5. Mitteilung. Über die Hydrierung des Kautschuks und über seine Konstitution|doi=10.1002/hlca.19220050517|date=1922|journal=Helvetica Chimica Acta|volume=5|issue=5|pages=785}}</ref> At that time the phrase ''polymer'', as introduced by [[Jöns Jakob Berzelius|Berzelius]] in 1833, had a different meaning from that of today: it simply was another form of [[isomerism]] for example with [[benzene]] and [[acetylene]] and had little to do with size.<ref name=Jensen>{{cite journal|doi=10.1021/ed085p624|title=The Origin of the Polymer Concept|date=2008|last1=Jensen|first1=William B.|journal=Journal of Chemical Education|volume=85|pages=624|issue=5|bibcode = 2008JChEd..85..624J }}</ref>
-Usage of the term to describe large molecules varies among the disciplines. For example, while [[biology]] refers to macromolecules as the four large molecules comprising living things, in [[chemistry]], the term may refer to aggregates of two or more molecules held together by [[intermolecular force]]s rather than [[covalent bond]]s but which do not readily dissociate.<ref>van Holde, K.E. (1998) ''Principles of Physical Biochemistry'' Prentice Hall: New Jersey, ISBN 0-13-720459-0</ref>
-According to the standard [[IUPAC]] definition, the term ''macromolecule'' as used in polymer science refers only to a single molecule. For example,a single polymeric molecule is appropriately described as a "macromolecule" or "polymer molecule" rather than a "polymer", which suggests a [[Chemical substance|substance]] composed of macromolecules.<ref>{{cite journal|url=http://www.iupac.org/reports/1996/6812jenkins/6812basicterms.pdf|journal=Pure and Applied Chemistry |volume=68|page=2287|date=1996|author=Jenkins, A. D.|title=Glossary of Basic Terms in Polymer Science|doi=10.1351/pac199668122287|last2=Kratochvíl|first2=P.|last3=Stepto|first3=R. F. T.|last4=Suter|first4=U. W.|issue=12}}</ref>
-Because of their size, macromolecules are not conveniently described in terms of [[stoichiometry]] alone. The structure of simple macromolecules, such as homopolymers, may be described in terms of the individual monomer subunit and total [[molecular mass]]. Complicated biomacromolecules, on the other hand, require multi-faceted structural description such as the hierarchy of structures used to describe [[proteins]].　In [[British English]], the word "macromolecule" tends to be called "'''high polymer'''". <ref> [http://www.highpolymer.org.uk/ High Polymer Research Group] </ref>
-==Properties==
-{{Refimprove section|date=May 2013}}
-Macromolecules often have unusual physical properties that do not occur for smaller molecules.
-For example, [[DNA]] in a solution can be broken simply by sucking the solution through an ordinary straw because the [[Shearing (physics)|physical forces]] on the molecule can overcome the strength of its [[covalent bonds]]. The 1964 edition of [[Linus Pauling]]'s ''College Chemistry'' asserted that DNA in nature is never longer than about 5,000 [[base pair]]s.<ref>{{Cite book|title = College Chemistry|last = Pauling|first = Linus|publisher = W.H. Feeman and Company|year = 1964|isbn = |location = |pages = |url = https://archive.org/details/CollegeChemistry}}</ref> This error arose because biochemists were inadvertently [[Shearing (physics)|breaking]] their samples into fragments. In fact, the DNA of [[chromosome]]s can be hundreds of millions of base pairs long, packaged into [[chromatin]].
-Another common macromolecular property that does not characterize smaller molecules is their relative insolubility in water and similar solvents, instead forming [[colloids]]. Many require [[Salt (chemistry)|salts]] or particular [[ion]]s to dissolve in water. Similarly, many proteins will [[Denaturation (biochemistry)|denature]] if the solute concentration of their solution is too high or too low.
-High concentrations of macromolecules in a solution can alter the [[reaction rate|rates]] and [[equilibrium constant]]s of the reactions of other macromolecules, through an effect known as [[macromolecular crowding]].<ref name="Minton">{{cite journal |author=Minton AP |title=How can biochemical reactions within cells differ from those in test tubes? |journal=J. Cell. Sci. |volume=119 |issue=Pt 14 |pages=2863–9 |date=2006 |pmid=16825427 |doi=10.1242/jcs.03063}}</ref> This comes from macromolecules [[excluded volume|excluding]] other molecules from a large part of the volume of the solution, thereby increasing the [[activity (chemistry)|effective concentrations]] of these molecules.
-== Linear biopolymers ==
-All [[Organism|living organisms]] are dependent on three essential [[biopolymers]] for their biological functions: [[DNA]], [[RNA]] and [[Proteins]].<ref name="isbn1-4292-2936-5">{{cite book |author = Berg, Jeremy Mark; Tymoczko, John L.; Stryer, Lubert|title = Biochemistry, 7th ed. (Biochemistry (Berg))|publisher = W.H. Freeman & Company|location = |year = 2010|pages = |isbn = 1-4292-2936-5|oclc = |doi = |accessdate = }} Fifth edition available online through the NCBI Bookshelf: [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer link]</ref> Each of these molecules is required for life since each plays a distinct, indispensable role in the [[Cell (biology)|cell]].<ref name="isbn0-8153-4111-3">{{cite book |author = Walter, Peter; Alberts, Bruce; Johnson, Alexander S.; Lewis, Julian; Raff, Martin C.; Roberts, Keith|title = Molecular Biology of the Cell (5th edition, Extended version)|publisher = Garland Science|location = New York|year = 2008|pages = |isbn = 0-8153-4111-3|oclc = |doi = |accessdate = }}. Fourth edition is available online through the NCBI Bookshelf: [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4 link]</ref> The simple summary is that [[Central dogma of molecular biology|DNA makes RNA, and then RNA makes proteins]].
-DNA, RNA and proteins all consist of a repeating structure of related building blocks ([[Nucleotides|nucleotide]]s in the case of DNA and RNA, [[amino acids]] in the case of proteins). In general, they are all unbranched polymers, and so can be represented in the form of a string. Indeed, they can be viewed as a string of beads, with each bead representing a single nucleotide or amino acid monomer linked together through [[Covalent bond|covalent chemical bonds]] into a very long chain.
-In most cases, the monomers within the chain have a strong propensity to interact with other amino acids or nucleotides. In DNA and RNA, this can take the form of Watson-Crick [[base pair]]s (G-C and A-T or A-U), although many more complicated interactions can and do occur.
-=== Structural features ===
-{| class="wikitable floatright"
-!
-! href="Nobel Prize" | DNA
-! href="Hermann Staudinger" | RNA
-! Proteins
-|-
-| href="Jöns Jakob Berzelius" | Encodes genetic information
-| href="isomerism" | Yes
-| href="benzene" | Yes
-| href="acetylene" | No
-|-
-| href="biology" | Catalyzes biological reactions
-| href="chemistry" | No
-| href="intermolecular force" | Yes
-| href="covalent bond" | Yes
-|-
-| href="IUPAC" | Building blocks (type)
-| Nucleotides
-| href="Chemical substance" | Nucleotides
-| Amino acids
-|- href
-| resource="Image:Dendrimer ChemEurJ 2002 3858.jpg" height width | Building blocks (number)
-| 4
-| href="dendrimer" | 4
-| 20
-|- href="stoichiometry"
-| href="molecular mass" | Strandedness
-| href="proteins" | Double
-| Single <td role="presentation"> Single</td>
-|- href="Category:All articles needing additional references"
-| Structure
-| Double helix
-| href="DNA" | Complex
-| href="Shearing (physics)" | Complex
-|- href="covalent bonds"
-| href="Linus Pauling" | Stability to degradation
-| High
-| href="base pair" | Variable
-| href="Shearing (physics)" | Variable
-|- href="chromosome"
-| href="chromatin" | Repair systems
-| Yes
-| href="colloids" | No
-| href="Salt (chemistry)" | No
-|}
-Because of the double-stranded nature of DNA, essentially all of the nucleotides take the form of [[Watson-Crick pairs|Watson-Crick base pair]]s between nucleotides on the two complementary strands of the [[Double-Helix|double-helix]].
-In contrast, both RNA and proteins are normally single-stranded. Therefore, they are not constrained by the regular geometry of the DNA double helix, and so fold into complex [[Biomolecular structure|three-dimensional shape]]s dependent on their sequence. These different shapes are responsible for many of the common properties of RNA and proteins, including the formation of specific [[Binding site|binding pockets]], and the ability to catalyse biochemical reactions.
-==== DNA is optimised for encoding information ====
-[[DNA]] is an information storage macromolecule that encodes the complete set of [[Nucleic acid sequence|instructions]] (the [[genome]]) that are required to assemble, maintain, and reproduce every living organism.<ref name="isbn978-0062730992">{{cite book |author = Golnick, Larry; Wheelis, Mark.|title = The Cartoon Guide to Genetics|publisher = Collins Reference|year = |isbn = 978-0-06-273099-2|oclc = |doi = |accessdate = }}</ref>
-DNA and RNA are both capable of encoding genetic information, because there are biochemical mechanisms which read the information coded within a DNA or RNA sequence and use it to generate a specified protein. On the other hand, the sequence information of a protein molecule is not used by cells to functionally encode genetic information.<ref name="Stryer_2002"/>{{Rp|5}}
-DNA has three primary attributes that allow it to be far better than RNA at encoding genetic information. First, it is normally double-stranded, so that there are a minimum of two copies of the information encoding each gene in every cell. Second, DNA has a much greater stability against breakdown than does RNA, an attribute primarily associated with the absence of the 2'-hydroxyl group within every nucleotide of DNA. Third, highly sophisticated DNA surveillance and repair systems are present which monitor damage to the DNA and [[DNA repair|repair]] the sequence when necessary. Analogous systems have not evolved for repairing damaged RNA molecules. Consequently, chromosomes can contain many billions of atoms, arranged in a specific chemical structure.
-==== Proteins are optimised for catalysis ====
-[[Proteins]] are functional macromolecules responsible for [[Enzyme catalysis|catalysing]] the [[Metabolism|biochemical reaction]]s that sustain life.<ref name="Stryer_2002"/>{{Rp|3}} Proteins carry out all functions of an organism, for example photosynthesis, neural function, vision, and movement.<ref name="isbn978-1593272029">{{cite book |author = Takemura, Masaharu|title = The Manga Guide to Molecular Biology|publisher = No Starch Press|location = |year = 2009|pages = |isbn = 978-1-59327-202-9|oclc = |doi = |accessdate = }}</ref>
-The single-stranded nature of protein molecules, together with their composition of 20 or more different amino acid building blocks, allows them to fold in to a vast number of different three-dimensional shapes, while providing binding pockets through which they can specifically interact with all manner of molecules. In addition, the chemical diversity of the different amino acids, together with different chemical environments afforded by local 3D structure, enables many proteins to act as [[Enzymes]], catalyzing a wide range of specific biochemical transformations within cells. In addition, proteins have evolved the ability to bind a wide range of [[Cofactor (biochemistry)|cofactors]] and [[Coenzymes]], smaller molecules that can endow the protein with specific activities beyond those associated with the polypeptide chain alone.
-==== RNA is multifunctional ====
-[[RNA]] is multifunctional, its primary function is to [[Protein synthesis|encode proteins]], according to the instructions within a cell’s DNA.<ref name="Stryer_2002"/>{{Rp|5}} They control and regulate many aspects of protein synthesis in [[eukaryote]]s.
-RNA encodes genetic information that can be [[Translation (biology)|translated]] into the amino acid sequence of proteins, as evidenced by the messenger RNA molecules present within every cell, and the RNA genomes of a large number of viruses. The single-stranded nature of RNA, together with tendency for rapid breakdown and a lack of repair systems means that RNA is not so well suited for the long-term storage of genetic information as is DNA.
-In addition, RNA is a single-stranded polymer that can, like proteins, fold into a very large number of three-dimensional structures. Some of these structures provide binding sites for other molecules and chemically-active centers that can catalyze specific chemical reactions on those bound molecules. The limited number of different building blocks of RNA (4 nucleotides vs >20 amino acids in proteins), together with their lack of chemical diversity, results in catalytic RNA ([[ribozymes]]) being generally less-effective catalysts than proteins for most biological reactions.
-== Branched biopolymers ==
-[[File:Raspberry ellagitannin.png|thumb|250px|right|[[Raspberry ellagitannin]], a [[tannin]] composed of core of glucose units surrounded by gallic acid esters and ellagic acid units]]
-[[Carbohydrates|Carbohydrate]] macromolecules ([[polysaccharide]]s) are formed from polymers of [[monosaccharides]].<ref name="Stryer_2002"/>{{Rp|11}} Because monosaccharides have multiple [[functional groups]], polysaccharides can form linear polymers (e.g. [[cellulose]]) or complex branched structures (e.g. [[glycogen]]). Polysaccharides perform numerous roles in living organisms, acting as energy stores (e.g. [[Starch]]) and as structural components (e.g.[[chitin]] in arthropods and fungi). Many carbohydrates contain modified monosaccharide units that have had functional groups replaced or removed.
-[[Polyphenol]]s consist of a branched structure of multiple [[Phenols#Naturally occurring|phenolic]] subunits. They can perform structural roles (e.g. [[lignin]]) as well as roles as [[secondary metabolites]] involved in [[Cell signaling|signalling]], [[plant pigment|pigmentation]] and [[plant toxin|defense]].
-== Synthetic macromolecules ==
-[[Image:Dendrimer ChemEurJ 2002 3858.jpg|thumbnail|250px|Structure of a polyphenylene [[dendrimer]] macromolecule reported by Müllen, et al.<ref>{{cite journal | doi = 10.1002/1521-3765(20020902)8:17<3858::AID-CHEM3858>3.0.CO;2-5 | title = Single-Crystal Structures of Polyphenylene Dendrimers | date = 2002 | author = Roland E. Bauer, Volker Enkelmann, Uwe M. Wiesler, Alexander J. Berresheim, Klaus Müllen| volume = 8 | pages = 3858 | issue = 17 | journal = Chemistry – A European Journal}}</ref>]]Some examples of macromolecules are synthetic polymers ([[plastic]]s, [[synthetic fiber]]s, and [[synthetic rubber]]), [[graphene]], and [[carbon nanotube]]s.
-==References==
-{{reflist|35em}}
-* {{cite book
-  | last = Tanford
-  | first = Charles |authorlink=Charles Tanford
-  | title = Physical Chemistry of Macromolecules
-  | publisher = [[John Wiley & Sons]]
-  | date = 1961
-  | location = [[New York City|New York]], NY
-  | pages =
-  | url =
-  | doi =
-  | id =
-  | isbn = }}
-==External links==
-* [http://www.mansfield.ohio-state.edu/~sabedon/campbl05.htm Synopsis of Chapter 5, Campbell & Reece, 2002]
-* [http://www.langara.bc.ca/biology/mario/Biol1115notes/biol1115chap5.html Lecture notes on the structure and function of macromolecules]
-* [http://swift.cmbi.ru.nl/teach/courses/ Several (free) introductory macromolecule related internet-based courses]
-* [https://web.archive.org/web/20060902103714/http://www.issa.stevens.edu/ISSA_Review/Files/Spring2003_Newsletter.pdf Giant Molecules!] by Ulysses Magee, ''ISSA Review'' Winter 2002–2003, [[ISSN]] 1540-9864. Cached HTML version of a missing PDF file. Retrieved March 10, 2010. The article is based on the book, ''Inventing Polymer Science: Staudinger, Carothers, and the Emergence of Macromolecular Chemistry'' by Yasu Furukawa.
-{{biological organisation}}
-{{Authority control}}
-[[Category:Molecules]]
-[[Category:Molecular physics]]
-[[Category:Biochemistry]]
-[[Category:Polymer chemistry]]
-[[Category:Polymers]]