breifly describe the structure and function of cell wall
Answers
Answer:
A cell wall is a rigid, semi-permeable protective layer in some cell types. This outer covering is positioned next to the cell membrane (plasma membrane) in most plant cells, fungi, bacteria, algae, and some archaea. Animal cells however, do not have a cell wall. The cell wall has many important functions in a cell including protection, structure, and support.
Cell wall composition varies depending on the organism. In plants, the cell wall is composed mainly of strong fibers of the carbohydrate polymer cellulose. Cellulose is the major component of cotton fiber and wood, and it is used in paper production. Bacterial cell walls are composed of a sugar and amino acid polymer called peptidoglycan. The main components of fungal cell walls are chitin, glucans, and proteins.
The plant cell wall is multi-layered and consists of up to three sections. From the outermost layer of the cell wall, these layers are identified as the middle lamella, primary cell wall, and secondary cell wall. While all plant cells have a middle lamella and primary cell wall, not all have a secondary cell wall.
Middle lamella: This outer cell wall layer contains polysaccharides called pectins. Pectins aid in cell adhesion by helping the cell walls of adjacent cells to bind to one another.
Primary cell wall: This layer is formed between the middle lamella and plasma membrane in growing plant cells. It is primarily composed of cellulose microfibrils contained within a gel-like matrix of hemicellulose fibers and pectin polysaccharides. The primary cell wall provides the strength and flexibility needed to allow for cell growth.
Secondary cell wall: This layer is formed between the primary cell wall and plasma membrane in some plant cells. Once the primary cell wall has stopped dividing and growing, it may thicken to form a secondary cell wall. This rigid layer strengthens and supports the cell. In addition to cellulose and hemicellulose, some secondary cell walls contain lignin. Lignin strengthens the cell wall and aids in water conductivity in plant vascular tissue cells.
Explanation:
hope it helps you dear
follow me
Answer:
The cell wall is an outer protective membrane in many cells including plants, fungi, algae, and bacteria. ... The main functions of the cell wall are to provide structure, support, and protection for the cell. The cell wall in plants is composed mainly of cellulose and contains three layers in many plants.
A cell wall is defined as the non-living component, covering the outmost layer of a cell. Its composition varies according to the organism and is permeable in nature. The cell wall separates the interior contents of the cell from the exterior environment. It also provides shape, support, and protection to the cell and its organelles. However, this cellular component is present exclusively in eukaryotic plants, fungi, and few prokaryotic organisms.
As stated above, fungi also possess cell walls, but they are made up of chitin, a derivative of glucose which is also found in the exoskeletons of arthropods. And just like the cell walls in plants, they provide structural support and prevents desiccation.
Prokaryotic organisms such as bacteria also contain cell walls. However, they are chemically different from the cell wall found in plants and fungi. The prokaryotic cell walls are composed of large polymers known as peptidoglycans. Cell walls in prokaryotes serve as a form of protection and prevent lysis (bursting of the cell and expulsion of cellular contents). Structurally, prokaryotic cell walls consist of two layers:
An inner layer that is made up of peptidoglycans
An outer layer that is composed of lipoproteins and lipopolysaccharides
Eukaryotic cells possess a definite nucleus along with a distinct nuclear membrane. It also contains membrane-bound organelles not found in prokaryotic cells. Another important point to note is that the cell wall is absent in other eukaryotic organisms such as animals, only plants possess cell walls.
Explore more: Eukaryotic cells
Cell Wall Structure
The cell wall is the outer covering of a cell, present adjacent to the cell membrane, which is also called the plasma membrane. As mentioned earlier, the cell wall is present in all plant cells, fungi, bacteria, algae, and some archaea. An animal cell is irregular in their shape and this is mainly due to the lack of cell wall in their cells. The compositions of the cell wall usually vary along with organisms.
The plant cell wall is generally arranged in 3 layers and composed of carbohydrates, like pectin, cellulose, hemicellulose and other smaller amounts of minerals, which form a network along with structural proteins to form the cell wall. The three major layers are:
Primary Cell Wall
The Middle Lamella
The Secondary Cell Wall
Primary Cell Wall
The primary cell is situated closest to the inside of the cell and is the first-formed cell wall. It is mainly made up of cellulose, allowing the wall to stretch for the purpose of growth. Several primary cells contain pectic polysaccharides and structural proteins. It is also comparatively permeable and thinner than the other layers.
Middle Lamella
The middle lamella is also the outermost layer and it acts as an interface between the other neighbouring cells and glues them together. This layer primarily consists of pectins. However, other substances such as lignin and proteins can also be found.
Secondary Cell Wall
The secondary cell wall is formed inside the primary cell wall once the cell is completely grown. Some types of cells (especially the cells of xylem tissues) consist of cellulose and lignin and these provide additional rigidity and waterproofing. Also, this layer provides the characteristic rectangular or square shape to a cell. It is also the thickest layer and permits permeability.
Explanation: