La célula (Membrana celular) Estructura y funciones | Bicapa lipídica | Biología (Parte 2).

Understanding the Cell Membrane

Introduction to the Cell Membrane

• The cell membrane, also known as the plasma membrane, is described as the outer covering of a cell.

• It is characterized as a thin, elastic, and flexible structure with a thickness of 7.5 to 10 nanometers, primarily composed of proteins and lipids.

• Cholesterol and other lipids are integral parts of its structure, contributing to its functionality.

Key Functions of the Cell Membrane

• One primary function is to separate the extracellular environment from the intracellular space (cytoplasm).

• The membrane's lipid bilayer plays a crucial role in this separation.

Lipid Bilayer Structure

• The lipid bilayer consists of two layers of lipids, each one molecule thick.

• Phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails; this dual nature facilitates membrane formation.

• The arrangement leads to permeability characteristics that determine how substances enter or exit the cell.

Membrane Proteins

• Membrane proteins float within the lipid bilayer and can be categorized into two main groups: integral proteins and peripheral proteins.

• Integral proteins span across the entire membrane thickness, forming channels for water-soluble molecules like ions.

• Peripheral proteins attach only to one side of the membrane without traversing it.

Role of Carbohydrates in Cell Membranes

• Carbohydrates attached to proteins (glycoproteins) or lipids (glycolipids), form a carbohydrate coating on the extracellular surface known as glycocalyx.