![]() Polar heads (hydrophilic) face outside and nonpolar (hydrophobic) hydrocarbon tail hides inside making micelle (C) biological membrane made up of amphipathic lipids with integral protein and (D) CTAB captures the membrane lipids and forms the hybrid micelle.ĬTAB works differently based on the ionic strength of the solution. It has long hydrocarbon chain (hydrophobic tail) and positively charged trimethylammonium group (hydrophilic head) (B) CTAB forms the micelle into the aqueous solution. Plant tissue, which is rich in complex polysaccharides and secondary metabolites, interfere and co-precipitate with DNA CTAB along with some other chemicals like PVP is used to minimize the effect of these metabolites.ĬTAB’s role in removing membrane. During DNA extraction, under aqueous condition, CTAB comes in contact with the biological membrane, captures the lipids ( Figure 1), and results in the release of nucleus, which is devoid of membrane. It forms micelle in water because of the amphipathic nature. ![]() ĬTAB, a cationic detergent, constitutes a long hydrophobic hydrocarbon chain and a hydrophilic head. Ionic surfactant has been always better in denaturing protein molecules, and thus in dissolving the membranes. Surfactants are characterized based on their hydrophilic group, that is, ionic, nonionic, and zwitterionic. It dissolves in surfactant, detergents, which are amphipathic (hydrophobic tail and hydrophilic head) in nature, very much similar to phospholipid membranes. This can be weakened to open the cell wall, by applying mechanical force exerted during grinding along with CTAB buffer or liquid nitrogen.Ĭell membrane lies next to the cell wall and cellulose and is composed of a diverse set of phospholipid molecules and proteins. The plant cells enclose themselves in complex polysaccharide cell wall, of which cellulose is a major constituent, which is crystalline in nature, due to chain-like structure and intermolecular hydrogen bonding. The role of various chemicals involved in CTAB extraction method has been described in the present communication. The majority of the protocols developed for DNA extraction are modified versions of hexadecyltrimethylammonium bromide (CTAB) extraction. The plant DNA is extracted by either CTAB-based or sodium dodecyl sulfate (SDS)-based methods. The basic principle of DNA isolation is disruption of the cell wall, cell membrane, and nuclear membrane to release the highly intact DNA into solution followed by precipitation of DNA and removal of the contaminating biomolecules such as the proteins, polysaccharides, lipids, phenols, and other secondary metabolites by enzymatic or chemical methods. Generally, leaf samples contain large quantities of polyphenols, tannins, and polysaccharides. The main objective of various DNA isolation methods is development of relatively quick, inexpensive, and consistent protocol to extract high-quality DNA with better yield. If liquid nitrogen is unavailable, CTAB buffer can be used directly or prewarmed for grinding. Generally fresh leaves aged 15–20 days are preferred for plant tissues (fresh, freeze-dried, or frozen in liquid nitrogen) and usually ruptured by mechanical force in pestle and motor or TissueLyser. These contaminants can be removed during extraction by standardizing basic DNA extraction protocol. The amount of these components varies according to plant species, plant part used, environmental condition, and growth stage and it is very problematic when isolating DNA. For example, cereals are rich in carbohydrates whereas medicinal plants are rich in the polyphenols wherein stressed plants have higher polyphenols. Maintaining yield and quality of DNA during plant DNA extraction is one of the difficult tasks compared to that of animals, because of its rigid cell wall, which is made up of cellulose along with other variable levels of chemical components such as polysaccharides, polyphenols, proteins, and lipids that act as a contaminant during DNA extraction. The isolation of good-quality DNA is the prerequisite for molecular research.
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