![]() ![]() ![]() Primary wall – It is the middle layer and is made of cellulose and hemicellulose.Middle lamella – It is the outermost layer and is made of calcium pectates.The cell wall is divided into the following three layers: Cellulose, galactans, mannans and calcium carbonate – in fungi.Cellulose, hemicellulose, proteins, and pectin – in plants.Structure and composition: It is made of different components in different Eukaryotes: It is absent in Eukaryotic cells of animals Thus, it does not need carrier proteins and is not selective.īrowse more Topics under Cell The Unit Of Lifeĭescription: The cell wall is a non-living, rigid structure outside the plasma membrane in plant cells and fungi. Passive transport – This transport occurs along the concentration gradient and therefore, does not require energy.It also needs carrier proteins and is a highly selective process. Active transport – This transport occurs against the concentration gradient and therefore, requires energy.It allows transport of molecules across the membrane.It is also important for secretion, cell growth, and division etc. The fluid nature of the membrane allows the interaction of molecules within the membrane.It protects the cells from shock and injuries.it allows only selected substances to pass through. ![]() The plasma membrane is selectively permeable i.e.Orange circles – Hydrophilic heads Lines below – Hydrophobic tails. The reason is that the bi-layer looks like a mosaic and has a semi-fluid nature that allows lateral movement of proteins within the bilayer. Scientists Singer and Nicolson described the structure of the phospholipid bilayer as the ‘Fluid Mosaic Model’. The non-polar, hydrophobic (water-repelling) tails are sandwiched between the heads and are protected from the aqueous environments.These heads interact with the aqueous environment outside and within a cell. The polar, hydrophilic (water-loving) heads face the outside and inside of the cell.These phospholipids are arranged as follows: Structure and Composition: In eukaryotic cells, the plasma membrane consists of proteins, carbohydrates and two layers of phospholipids (i.e. The plasma membrane is a semi-permeable membrane that separates the inside of a cell from the outside. Description: It is also called plasma membrane or cell membrane. ![]()
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