Colenkim Cell Composition and Fiber Sclerenkim
Can be found on stems, leaves as well as in the flowers, fruit and roots, especially if the roots are exposed to light. Colenchymal cell walls are examples of primary walls that expand and thicken as cells grow enlarged. Colenchymal walls consist mainly of cellulose and pectin compounds and contain a lot of water. Fresh colchemical wall ingredients contain about 67% water. Fahn (1982) states that according to Roelofsen, the collenchyma cell wall contains 45% pectin, 35% hemicellulose and about 20% cellulose.
Colenkim cell composition
Colenchymal cells have active protoplasts that are able to eliminate wall thickening when cells are stimulated to divide as they form cork cambium. Colenchymes such as parenchyma can contain chloroplasts so they can carry out photosynthesis.
Type Or Kinds Of Kolenkim
Angular Kolenkim (angular)
Thickening takes place at the corners, and extends along the axis of the cell. For example, in the leaf stalks of Vitis sp, Begonia sp, Solanum tuberosum.
Board Kolenkim (lamellar)
Thickening occurs in the tangential cell wall (parallel to the surface of the organ), so that the transverse slices look like rows of boards. For example, in the cortex of the Sambucus javanica stem.
Tubular collagen (lacuna)
It is present in the kolenkim which has intercellular spaces and its thickening occurs on the surface of the space between the cells. For example, on the leaf stalks Salvina, Malva, and Althaea.
Ring type kolenkim
At the cross section of the cell the lumen is circular. At the time of adulthood it appears that because of the type of continuous thickening angle on the cell wall, the lumen no longer angles.
Kinds of Kolenkim
Sklerenkim Network
Sclerenkim tissue is a supporting network found in plant organs that are no longer experiencing growth and development or in mature plants. The sclerenkim tissue consists of fibers (sclerenkim fibers) and sclereid (stone cells).
Sclerenkim tissue is a mechanical network that is only found in plant organs that no longer hold growth and development or plant organs that have been fixed. Sklerenkim serves to deal with all pressures so that it can protect weaker tissues.
Sklerenkim does not contain protoplasts, so the cells have died. The cell wall is thick due to a previous secondary thickening consisting of lignin.
Characteristics of cells in the sclerenkim tissue
The cells have died with thick cell walls
Thick secondary walls, generally composed of lignin
Chewy, generally no longer contains chloroplasts
The cells are stiffer than kolenkim, sclerekim cells cannot elongate
Type of sklerenkim network
A. The Fiber Sclerenkim (Fibers)
The sclerenkim fibers are made up of cells that are ± 2 mm long and have pointed edges. The sclerenkim fibers are cells that are already dead. The cell wall thickens from wood and contains lamella-cellulose lamellar so that the cell lumen is narrow. This fiber is in the form of a polygon, which is a pentagon or hexagon. The dots are narrow shaped like narrow slanted channels. The sclerenkim fibers in plants are formed together with the cessation of the growth of organs in plants.
The sclerenkim fibers are in the form of separate strands or in the form of circles in the cortex and phloem, in groups that are spread out in the xylem and phloem. In Gramineae, the sclerenkim fibers are arranged in a curved circular system connected to the epidermis. For more details, consider the following picture:
There are two types of sclerenkim fibers, which are as follows.
(1) Fibers Outside the Xylem (Extraxilaries)
Extraxilari fibers have lignin and some don't. This fiber can be used to make ropes, jute sacks, and textiles for clothing.
(2) Xylem Fiber (Xylem)
This type of fiber is the main component of wood because the walls contain lignin which causes the walls to be hard and stiff.
B. Stone Cells (Sklereid)
Sclereid is found in plant parts, including in the cortex, phloem, fruit and seeds. The sclereid wall is composed of cellulose which contains thick and hard lignin. In some plants, suberin and cutin are also sometimes found. The cells have narrow dots and circular gaps, forming channels called dots. The cell lumen is very narrow because of the thickening of the cell walls.
Sclereid may be found in singular or small clusters between cells, for example granules such as sand in guava flesh or a continuous period as in hard coconut shells. To understand the structure of these stone cells, consider the following picture!
Questions:
Question from group 1, by Katarina Nay.
Question: Why are colenchymes rarely found in the roots?
Answer: because the cellulose-walled kolenkim tissue and its function is only to strengthen young and woody stems. While at the root, there is a phloem network that functions to strengthen plants.
Question from group 3, by Selsiana Bara.
Question: why does the cell wall thickening collenchyma only occur in the tangesial cell wall?
Answer: because in some kinds of collenchyma, it has been divided based on their respective thickening spots. Like, the angle collagen that is thickening only occurs at the corner only and so is the case with a thick column that occurs in the tangesial cell wall (parallel to the surface of the organ).
Question from group 5, by Maria Lewa
Question: Explain the function of skelerenkim fibers and skelereid?
Answer: Both of these fibers have the same function, namely to deal with all pressures so as to protect weaker tissues and as a reinforcement, because they contain lignin (wood)