Cell Membrane Structure and Function

Study Notes

Three ways to refer to the cell membrane: membrana celular, membrana plasmática, and bicapa lipídica.
The cell membrane is a semipermeable biological barrier separating the cell from its external environment.
Components of the cell membrane: lipids (40%), proteins (50%), and carbohydrates (10%).
The main lipids in the cell membrane are phospholipids, glycolipids, and cholesterol.
Phospholipids are organized into a lipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
Phospholipids have polar heads (hydrophilic) and nonpolar tails (hydrophobic).
Examples of phospholipids in the cell membrane include phosphatidylcholine, phosphatidylserine, and phosphatidylinositol.
Cholesterol in the cell membrane is amphipathic, with hydrophilic and hydrophobic regions.
The concept of fluidity in the cell membrane refers to the movement of lipids, crucial for cell functions like exocytosis and endocytosis.
Factors affecting membrane fluidity include the degree of saturation of lipid tails, temperature, and the amount of cholesterol present.- Membrane fluidity is crucial for cell survival and depends on lipid composition, cholesterol content, and temperature.
Proteins in the cell membrane are classified into integral proteins (transmembrane) and peripheral proteins.
Integral proteins have three parts: extracellular domain, transmembrane domain, and cytoplasmic domain.
Examples of integral proteins include channel proteins and carrier proteins (transporters) which facilitate substance transport.
Channel proteins have a central channel for substances to pass through, while carrier proteins change shape to transport substances.
Peripheral proteins are located on one side of the membrane and play a role in cell signaling by interacting with hormones or neurotransmitters.
Carbohydrates are mainly found on the external surface of the cell and can be attached to proteins (glycoproteins) or lipids (glycolipids).
The glycocalyx refers to the layer of carbohydrates covering the cell surface, involved in cell recognition and protection.

Description

Explore the structure and functions of the cell membrane, including its components like lipids, proteins, and carbohydrates. Learn about the organization of phospholipids in a lipid bilayer, the role of cholesterol, and the importance of membrane fluidity for cellular processes.