Cell Wall and Plasma Membrane
The cell wall was discovered by Robert Hooke in 1665 earlier than the protoplast it is the outermost boundary of the plant cell. It is secreted by the protoplasm of the cell its thickness very easy and different cells of the plants each cell with isolated or occurring in tissue has its own cell wall. The cell walls of the neighbouring cells are held together by an intercellular substance called the middle lamella silver is greatly in morphology and chemical composition. But its characteristics a close relation with age and function of the cell. On the basis of the development and structure, the cell wall has three fundamental parts namely
- middle lamella
- number 2 two primary wall
- and number 3 secondary wall
The middle Lamella join together it is usually thin and about 1 micrometre in thickness. In Woody tissue in the middle lamella is commonly lignified what is the first wall form in the developing cell it is usually 1-3 micrometre in thickness more or less elastic and extendable crystalline and optically active it is composed of cellulose pectic compounds and mostly polysaccharide and hemicellulose.
The secondary wall follows the order of primary wall in development it is inside the primary wall it is usually thick about 5 to 10 micrometre more or less result crystalline and strongly optically active it is mainly composed of cellulose polysaccharide hemicellulose and minerals such as calcium magnesium potassium and some silica.
The plasma membrane or cell membrane is the outermost boundary of the animal cell and inner to cell wall in plant cell. Cell membrane is chemically composed of lipids which is 20 to 40% proteins which are 60 to 80%, in addition, there is a small quantity of carbohydrates are also presents which are 5 to 10% largest contributor to establish the structural organisation of cell membrane the modern technology has revealed that lipid bilayer is not sandwiched.
In 1972 singer and Nicolson proposed the most acceptable model which is known as fluid mosaic model which is according to the agreement and with the photograph of the cell membrane with electron microscope this model explains that the membrane is like a sea of lipids in which the proteins are floating.
The other most important part of the plasma membrane is cytoplasm. Which is the living content of the eukaryotic cells which are divided into the nucleus and cytoplasmic organelles forming protoplasm set a plasma contains 90% water so-called the fluid part of the cell the soluble part of the cytoplasm forms the ground substance between the cell and organelle is which is known as cytosol. It is form of about 90% water and other solution which contain all the fundamentals biochemical of life and cytosol small molecules and ions main form true solution and some large molecules form colloidal solution apart from acting as a storage of vital chemicals the ground substance of cytoplasm is the site of certain metabolic pathways such as glycolysis in which energy production take place. All important cell organelle is also present within the cytoplasm which male include endoplasmic reticulum Golgi complex plastids ribosomes lysosomes mitochondria and other important cytoplasmic organelles.