Summary of MEMBRANA CELULAR: estructura y funciones

00:00:00 - 00:05:00

This video discusses the structure and function of the cell membrane. The membrane is made up of a double layer of lipids with proteins intercalated between them. The lipids are antipatic, meaning they have a polar hydrophilic head and two nonpolar hydrofobic chains. The proteins can be classified as periferal or extra-cellular, and they attach temporarily to the membrane layer either through water-phase or lipid-phase interactions. Active and passive transport across membranes are also covered, as well as the cell's role in signal transduction. Finally, the cell's identity is conferred via antigenic recognition.

• 00:00:00 The membrana celular, also known as plasmatic membrane, is a structure that separates cells and allows for different cell populations to exist within them. In 1972, singer and Nicholson proposed a model of fluid mosaic for explaining the structure and function of the plasmatic membrane. This model refers to the combination of lipids and proteins that make up the membrane, which is dynamic. All biological membranes share a basic structure, which consists of a double layer of lipids with proteins intercalated between them. Lipids in the plasmatic membrane belong to three fatty acid classes: group lipids and esters. The main fatty acids in the plasmatic membrane are the fosfolipids, which have an antipatic property. This means that they possess a polar hydrophilic head and interact with water, and have two nonpolar hydrofobic chains. They form a double bilayer with lipids on both surfaces, known as the bicapa lipidic. In anhydrous phase between them, the lipids are asymmetric, with the outer layer being more solid and containing fosfolipids fosfatidilcolina and sphingomyelinase. The outer layer also contains glucidic molecules in its surface
• 00:05:00 Membrana cellular structure and functions are discussed in this video. The percentage of proteins to lipids is approximately 50/50, but this ratio is variable depending on the type of cell. For example, in a neuron it can be anywhere from 75/25 to 75/75 based on the type of protein-lipid association. Proteins can be classified as periferal or extra-cellular, and they attach temporarily to the membrane layer either through water-phase or lipid-phase interactions. Two integral membrane proteins are discussed in further detail: those that attach directly to the hydrofobic layer and those that traverse the membrane and are exposed on both sides. Their various functions include acting as channels and translators for passing molecules across the membrane, as well as providing the cell with antigenic specificity. Active and passive transport across membranes are also covered, as well as the cell's role in signal transduction. Finally, the cell's identity is conferred via antigenic recognition.