Illustration of a polypeptide macromolecule

The term macromolecule by definition implies "large molecule". Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In the context of biochemistry, the term may be applied to the four conventional biopolymers (nucleotides, proteins, carbohydrates, and lipids), as well as non-polymeric molecules with large molecular mass such as macrocycles. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Biopolymers are a class of Polymers produced by living organisms Nucleotides are Organic compounds that consist of three joined structures a nitrogenous base a Sugar, and a Phosphate group Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble A macrocycle is as defined by IUPAC, "a cyclic macromolecule or a macromolecular cyclic portion of a molecule

Usage

The term macromolecule was coined by Nobel laureate Hermann Staudinger in the 1920s although his first relevant publication on this field only mentions high molecular compounds (in excess of 1000 atoms). The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Hermann Staudinger ( March 23, 1881 &ndash September 8, 1965) was a German chemist who demonstrated the existence of Macromolecules Year 1920 ( MCMXX) was a Leap year starting on Thursday (link will display 1920 of the Gregorian calendar ^[1]. At that time the phrase polymer as introduced by 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 ^[2]. Friherre Jöns Jacob Berzelius (20 August 1779 &ndash 7 August 1848 was a Swedish chemist This article is about the chemical concept For "isomerism" of atomic nuclei see Nuclear isomer. Benzene, or benzol, is an organic Chemical compound and a known Carcinogen with the molecular formula C 6 H 6 Acetylene ( IUPAC name ethyne), C2H2 is a Hydrocarbon belonging to the group of Alkynes It is the simplest of all alkynes

Usage of the term to describe different forms of large molecules varies among the disciplines. For example, while biology refers to macromolecules as the four large molecules living things are composed of, from the perspective of chemistry, the term may refer to aggregates of two or more macromolecules held together by intermolecular forces rather than covalent bonds but which do not readily dissociate. Foundations of modern biology There are five unifying principles Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties In Physics, Chemistry, and Biology, intermolecular forces are forces that act between stable Molecules or between functional groups of ^[3]

According to the recommended IUPAC definition, the term macromolecule as used in polymer science refers only to a single molecule. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization For example, a single polymeric molecule is appropriately described as a "macromolecule" or "polymer molecule" rather than a "polymer", which suggests a substance composed of macromolecules. ^[4]

Structure of a polyphenylene dendrimer macromolecule reported by Müllen,k and coworkers in Chem. Dendrimers are repeatedly branched Molecules The huge number of papers on dendritic architectures such as dendrimers dendronized hyperbranched and brush-polymers has generated -Eur. J. , 2002, 3858-3864.

Because of their size, macromolecules are not conveniently described in terms of stoichiometry alone. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable The structure of simple macromolecules, such as homopolymers, may be described in terms of the individual monomer subunit and total molecular mass. The molecular mass (abbreviated m of a substance, more commonly referred to as molecular weight and abbreviated as MW, is the Mass of one Complicated biomacromolecules, on the other hand, require multi-faceted structural description such as the hierarchy of structures used to describe proteins. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl

Properties

Substances that are composed of macromolecules often have unusual physical properties. Although too small to see, individual pieces of DNA in solution can be broken in two simply by suctioning the solution through an ordinary straw. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known This is not true of smaller molecules. The 1964 edition of Linus Pauling's College Chemistry asserted that DNA in nature is never longer than about 5000 base pairs. Linus Carl Pauling (February 28 1901 – August 19 1994 was an American Scientist, Peace activist, Author and educator. In Molecular biology, two Nucleotides on opposite complementary DNA or RNA strands that are connected via Hydrogen bonds are called This is because biochemists were inadvertently and consistently breaking their samples into pieces. In fact, the DNA of chromosomes can be tens of millions of base pairs long. A chromosome is an organized structure of DNA and Protein that is found in cells.

Another common macromolecular property that does not characterize smaller molecules is the need for assistance in dissolving into solution. Many require salts or particular ions to dissolve in water. Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Proteins will denature if the solute concentration of their solution is too high or too low. Denaturation is a process in which Proteins or Nucleic acids lose their structure (tertiary structure by application of some external stress or compound for

References

External links

• Synopsis of Chapter 5, Campbell & Reece, 2002
• Lecture notes on the structure and function of macromolecules
• Several (free) introductory macromolecule related internet-based courses