Structural Components of the Cell Membrane PDF

Structural Components of the Cell Membrane  What is a Cell Membrane? The cell membrane also known as the plasma membrane, acts as the boundary between the cell and its external environment.  What is a Cell Membrane? It controls the movement of substances in and...

Structural Components of the Cell Membrane  What is a Cell Membrane? The cell membrane also known as the plasma membrane, acts as the boundary between the cell and its external environment.  What is a Cell Membrane? It controls the movement of substances in and out of the cell and plays a vital role in maintaining cell homeostasis.  Cell homeostasis Is the maintenance of stable conditions in cells. Homeostasis is crucial for cell function, optimal metabolism, growth and survival. Fluid Mosaic Model Is proposed in 1972 by Singer and Nicolson, is the widely accepted model describing the structure of cell membranes. Fluid Mosaic Model According to this model, the cell membrane is a fluid-like mosaic of lipids, proteins, and carbohydrates. Lipid Bilayer The lipid bilayer is the foundational structure of the cell membrane. Types of Lipids Phospholipi ds Cholesterol Glycolipids Phospholip ids Are amphipathic molecules with a hydrophilic (water- attracting) head and two hydrophobic (water- repelling) tails.  Phospholip ids These phospholipids align themselves in two layers, with their tails facing inward and heads facing outwards, creating a barrier to most polar and charged molecules.  The "head" of the molecule contains the phosphate group and is hydrophilic, meaning that it will dissolve in water The "tail" of the molecule is made up of two fatty acids, which are hydrophobic and do not dissolve in water. Cholester ol are interspersed within the bilayer, modulating membrane fluidity and stability. Glycolipids are lipids with attached carbohydrate chains, playing roles in cell recognition and signaling.  Proteins Proteins are the second major component of plasma membranes. There are two main categories of membrane proteins: integral and peripheral.  Integral proteins Embedded in the phospholipid bilayer; may or may not extend through both layers Periphera l proteins On the inner or outer surface of the phospholipid bilayer, but not embedded in its hydrophobic core Carbohydrates Carbohydrates are the third major component of plasma membranes. In general, they are found on the outside surface of cells and are bound either to proteins (forming glycoproteins) or to lipids (forming glycolipids) Glycoprote ins enable cells to recognize another cell as familiar or foreign, which is called cell-cell recognition. Glycoprote ins also help cells attach to and bind other cells, which is called cell adhesion. Thank You!