Lipids and Biological Membranes

These flashcards cover key vocabulary and concepts about lipids and biological membranes, important for understanding cell structure and function.

Biological membranes

Structures that enclose all cells, composed of lipids, proteins, and carbohydrates, performing functions like separating cellular contents and controlling molecule movement.

Lipid bilayer

A double-layered structure formed by lipids, where hydrophilic heads face outward towards water and hydrophobic tails face inward, protecting them from water.

Fatty acids

Hydrocarbon chains ending in a carboxylic acid group, classified as saturated, monounsaturated, or polyunsaturated based on their double bonds.

Saturated fatty acids

Fatty acids that have no double bonds in their hydrocarbon chain, leading to straight chains that pack tightly together.

Monounsaturated fatty acids

Fatty acids that have one double bond in their hydrocarbon chain, which introduces a kink in the structure.

Polyunsaturated fatty acids

Fatty acids with two or more double bonds, providing more flexibility and distinct advantages in biological functions.

Cholesterol

A type of sterol that is amphipathic, playing a crucial role in regulating the fluidity of lipid bilayers.

Glycerophospholipids

Lipids similar to triacylglycerols but with one fatty acid replaced by a phosphate group, essential for forming cell membranes.

Integral membrane proteins

Proteins that span the entire lipid bilayer, often functioning as transporters or receptors.

Peripheral membrane proteins

Proteins that do not penetrate the lipid bilayer but associate with integral proteins or lipid head groups.

Transporters

Proteins that facilitate the movement of ions and polar molecules across the membrane, requiring conformational changes.

Active transport

The energy-dependent movement of molecules against their electrochemical gradient, often utilizing ATP.

Passive transport

The spontaneous movement of molecules down their electrochemical gradient without energy input.

Fluid mosaic model

A model describing the structure of biological membranes, where proteins and lipids can move laterally within the bilayer.

Amphipathic molecules

Molecules that contain both hydrophobic and hydrophilic regions, essential for forming lipid bilayers and micelles.

Phospholipid translocases

Proteins that help maintain the asymmetry of lipid bilayers, such as flippases and scramblases.