lignin

Examples of lignin in the following topics:

• Thermosetting vs. Thermoplastic Polymers

  • A natural resinous polymer called lignin has a cross-linked structure similar to bakelite.
  • Lignin is the amorphous matrix in which the cellulose fibers of wood are oriented.
  • A partial structure for lignin is shown here:

• Bryophytes

  • However, because they lack of lignin and other resistant structures, bryophyte fossil formation is improbable and the fossil record is poor.
  • They generally lack lignin and do not have actual tracheids (xylem cells specialized for water conduction).

• Genomics and Biofuels

  • These include Clostridia species for their ability to degrade cellulose, and fungi that express genes associated with the decomposition of the most recalcitrant features of the plant cell wall, lignin, the phenolic "glue" that imbues the plant with structural integrity and pest resistance.
  • The white rot fungus Phanerochaete chrysosporium produces unique extracellular oxidative enzymes that effectively degrade lignin by gaining access through the protective matrix surrounding the cellulose microfibrils of plant cell walls.

• Dietary Fiber

  • Lignin, a major dietary insoluble fiber source, may alter the fate and metabolism of soluble fibers.
  • Chemically, dietary fiber consists of non-starch polysaccharides, cellulose, and many other plant components (e.g. lignin, waxes, chitins, pectin, among others) .
  • This model of a plant cell, showing the primary and secondary cell walls, as well as a vacuole (blue), illustrates the location of the dietary fiber sources lignin, pectin, and cellulose.

• Charales

  • They produce the compounds lignin and sporopollenin.

• Primary and Secondary Growth in Stems

  • The cells of the secondary xylem contain lignin, which provides hardiness and strength.

• Plant Adaptations to Life on Land

  • The evolution of a waxy cuticle and a cell wall with lignin also contributed to the success of land plants.

• Fungi Cell Structure and Function

  • Fungal exoenzymes are able to break down insoluble polysaccharides, such as the cellulose and lignin of dead wood, into readily-absorbable glucose molecules.

• Polycyclic Aromatic Hydrocarbons

  • The mycelium secretes extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber.

• Stem Anatomy

  • Both types have secondary cell walls that are thickened with deposits of lignin, an organic compound that is a key component of wood.