Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.
Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
A polymer is a substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals.
Polysaccharides, or polycarbohydrates, are the most abundant carbohydrate found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin.
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods like wheat, potatoes, maize (corn), rice, and cassava (manioc).
In genetics and biochemistry, sequencing means to determine the primary structure of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which succinctly summarizes much of the atomic-level structure of the sequenced molecule.
A macromolecule is a very large molecule, such as a protein. They are composed of thousands of covalently bonded atoms. Many macromolecules are polymers of smaller molecules called monomers. The most common macromolecules in biochemistry are biopolymers and large non-polymeric molecules such as lipids, nanogels and macrocycles. Synthetic fibers and experimental materials such as carbon nanotubes are also examples of macromolecules.
In biology, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate and residues that catalyse a reaction of that substrate. Although the active site occupies only ~10–20% of the volume of an enzyme, it is the most important part as it directly catalyzes the chemical reaction. It usually consists of three to four amino acids, while other amino acids within the protein are required to maintain the tertiary structure of the enzymes.
Ribozymes are RNA molecules that have the ability to catalyze specific biochemical reactions, including RNA splicing in gene expression, similar to the action of protein enzymes. The 1982 discovery of ribozymes demonstrated that RNA can be both genetic material and a biological catalyst, and contributed to the RNA world hypothesis, which suggests that RNA may have been important in the evolution of prebiotic self-replicating systems. The most common activities of natural or in vitro-evolved ribozymes are the cleavage or ligation of RNA and DNA and peptide bond formation. Within the ribosome, ribozymes function as part of the large subunit ribosomal RNA to link amino acids during protein synthesis. They also participate in a variety of RNA processing reactions, including RNA splicing, viral replication, and transfer RNA biosynthesis. Examples of ribozymes include the hammerhead ribozyme, the VS ribozyme, Leadzyme and the hairpin ribozyme.
A biomolecule or biological molecule is a loosely used term for molecules present in organisms that are essential to one or more typically biological processes, such as cell division, morphogenesis, or development. Biomolecules include large macromolecules such as proteins, carbohydrates, lipids, and nucleic acids, as well as small molecules such as primary metabolites, secondary metabolites and natural products. A more general name for this class of material is biological materials. Biomolecules are an important element of living organisms, those biomolecules are often endogenous, produced within the organism but organisms usually need exogenous biomolecules, for example certain nutrients, to survive.
A nuclease is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously affect single and double stranded breaks in their target molecules. In living organisms, they are essential machinery for many aspects of DNA repair. Defects in certain nucleases can cause genetic instability or immunodeficiency. Nucleases are also extensively used in molecular cloning.
Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. It is one of the two components of starch, making up approximately 20-30%. Because of its tightly packed helical structure, amylose is more resistant to digestion than other starch molecules and is therefore an important form of resistant starch.
Amylopectin is a water-soluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose.
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another.
Cycloamyloses are cyclic α-1,4 linked glucans comprising dozens or hundreds of glucose units. Chemically they are similar to the much smaller cyclodextrins, which are typically composed of 6, 7 or 8 glucose units.
Waxy corn or glutinous corn is a type of field corn characterized by its sticky texture when cooked as a result of larger amounts of amylopectin. The corn was first described from a specimen from China in 1909. As this plant showed many peculiar traits, the American breeders long used it as a genetic marker to tag the existence of hidden genes in other maize breeding programs. In 1922 a researcher found that the endosperm of waxy maize contained only amylopectin and no amylose starch molecule in opposition to normal dent maize varieties that contain both. Until World War II, the main source of starch in the USA was tapioca but when Japan severed the supply lines of the States, they forced processors to turn to waxy maize. Amylopectin or waxy starch is now used mainly in food products, but also in the textile, adhesive, corrugating and paper industry.
Enzyme mimic is a branch of biomimetic chemistry, which aims at imitating the function of natural enzymes. An enzyme mimic is a small molecule complex that models the molecular structure, spectroscopic properties, or reactivity of an enzyme, sometimes called bioinspired complexes.
DNA ends refer to the properties of the end of DNA molecules, which may be sticky or blunt based on the enzyme which cuts the DNA. The restriction enzyme belong to a larger class of enzymes called exonucleases and endonucleases. Exonucleases remove nucleotide from ends whereas endonuclease cuts at specific position within the DNA.
Floridean starch is a type of a storage glucan found in glaucophytes and in red algae, in which it is usually the primary sink for fixed carbon from photosynthesis. It is found in grains or granules in the cell's cytoplasm and is composed of an α-linked glucose polymer with a degree of branching intermediate between amylopectin and glycogen, though more similar to the former. The polymers that make up floridean starch are sometimes referred to as "semi-amylopectin".
