Microfibrils??

Question

Can anyone help me with my AS homework and tell me what Microfibrils do and why they are so useful in the cell wall in plant cells...pleaseeeee help me!!

Answer 1

Microfibril is the basic structural unit of the plant cell wall, made of cellulose in higher plants and most algae, chitin in some fungi and mannan or xylan in a few algae. Higher plant microfibrils are about 10nm in diameter and extremely long in relation to their width. The cellulose molecules are oriented parallel to the long axis of the microfibril in a paracrystalline array, which provides great tensile strength. The microfibrils are held in place by the wall matrix and their orientation is closely controlled by the protoplast.
Components of the extracellular matrix consisting primarily of fibrillin. They are essential for the integrity of elastic fibers.
Extracellular matrix components occurring independently or along with elastin. Thought to have force-bearing functions in tendon. In addition to fibrillins, microfibrils may contain other associated proteins.

Conventional electron microscopy and rotary shadowing techniques have provided conflicting interpretations of microfibril ultrastructure. To address this issuescientists have used quick-freeze deep-etch (QFDE) microscopy to obtain 3-dimensional surface views of microfibrils that have not been fixed, dehydrated, or stained with heavy metals. By this approach, microfibrils appear as tightly packed rows of bead-like subunits that do not display the interbead filamentous links seen by other methods. At regular 50-nm intervals along the microfibril length, a larger bead is often recognized which tends to be aligned with those from adjacent microfibrils when the microfibrils are in bundles. This evidence of organized lateral associations of microfibrils is supported by the observation of small filaments that span between the adjacent microfibrils. When QFDE microscopy was used to examine microfibrils exposed to sonication, partially dissociated microfibrils with the more typical "beads on a string" appearance were observed. Beads are also seen alone, as monomers, often with an array of small thread-like filaments extending from the bead in a "crab-like" manner. They have suggested that the beads on a string appearance of sonicated microfibrils may result from a partial loss of protein components from the interbead domains, thus leading to exposure of a filamentous substructure. It is possible, therefore, that this phenomenon might also contribute to the beads on a string appearance of microfibrils seen using other electron microscopy techniques.

Answer 2

The cell wall generally determines the shape of the bacterial cell. The wall is a tough but resilient shell that keeps bacterial cells from drying out and helps them resist environmental stress. In some cases the cell wall protects the bacterium from attack by the body’s disease-fighting immune system cells. Some bacteria do not have much of a cell wall, while others have quite thick structures. Many species of bacteria move about by means of flagella, hairlike structures that project through the cell wall. The flagellum’s rotating motion propels the bacterial cell toward nutrients and away from harmful substances.
Like all cells bacteria contain the genetic material DNA. But bacterial DNA is not contained within a nucleus, as is DNA in plant and animal cells. Most bacteria have a single coil of DNA, although some bacteria have multiple pieces. Bacterial cells often have extra pieces of DNA called plasmids, which the cell may gain or lose without dying. Surrounding the DNA in a bacterial cell is cytoplasm, a watery fluid that is rich in proteins and other chemicals. A cell membrane inside the wall holds together the DNA and the constituents of the cytoplasm. Most activities of the bacterial cell are carried out within the cytoplasm, including nutrition, reproduction, and the manufacture of proteins.

B How Bacteria Function
Bacterial cells, like all cells, require nutrients to carry out their work. These nutrients must be water soluble to enter through pores in the cell wall and pass through the cell membrane into the cytoplasm. Many bacteria, however, can digest solid food by secreting chemicals called exoenzymes into the surrounding environment. The exoenzymes help break down the solid food outside the bacteria into water-soluble pieces that the cell wall can absorb. Bacterial cells use nutrients for a variety of life-sustaining biochemical activities known collectively as metabolism.

Answer 3

The microfibril is a very fine fibril. It is usually, but not always, used as a general term in describing the structure of protein fibre, examples are hair and sperm tail. Its most frequently observed structural pattern is 9+2 pattern in which two central protofibrils are surrounded by nine others. Cellulose inside plants is one of the examples of non-protein compounds that are using this term with the same purpose.

Answer 4

its thin, hairlike but tinier. if you put a bundle of microfibrils together, you make a muscle cells, you bunch up muscle cells, you make a muscle bundle and a bunch of mucles bundles make your muscle. im not sure though y their are useful in cell plant cell. (this info is based on anatomy)