Membrane Structure & Function Flashcards

Vocabulary flashcards covering the structural components, lipid types, membrane proteins, carbohydrates, and functional properties of the cell membrane based on the lecture notes.

Fluid Mosaic Model

A model describing the cell membrane as fluid in nature, mosaic in pattern, and composed of a phospholipid bilayer where lipids and proteins move laterally.

Amphipathic

Describing a molecule that possesses both a hydrophilic, polar head and a hydrophobic, non-polar tail.

Phospholipids

The most abundant membrane lipids, consisting of a glycerol backbone, two fatty acid tails, and a phosphate group with an attached polar head.

Cholesterol

A sterol lipid with a rigid ring structure, a hydroxyl group (-OH), and a hydrocarbon tail that modulates membrane fluidity and stability.

Sphingolipids

A class of lipids derived from the aliphatic amino alcohol sphingosine, containing a hydrophobic region with a sphingoid long chain base and fatty acid chain attached by an amide bond at carbon 2.

Lipid Rafts

Specialized membrane microdomains that organize and concentrate certain proteins and lipids, formed with contributions from sphingolipids.

Integral Membrane Proteins

Amphipathic proteins with a transmembrane domain that penetrate the hydrophobic interior of the lipid bilayer and are tightly bound to the membrane.

Transmembrane Proteins

Also known as Integral Polytopic Proteins, these span the entirety of the cell membrane and can be single-pass or multi-pass.

Glycophorin A

An example of a single-pass transmembrane protein found in red blood cells that is involved in cell signaling or acts as a receptor.

Integral Monotopic Proteins

Integral membrane proteins embedded in only one side of the lipid bilayer, such as Prostaglandin H2 Synthase (Cyclooxygenase).

Lipid-Anchored Proteins

Proteins located on the membrane surface that are covalently attached to lipids embedded within the cell membrane.

Channel Proteins

Transport proteins that form hydrophilic pores in the membrane allowing passive movement of specific ions or molecules down their concentration gradient.

Carrier Proteins

Transport proteins (transporters) that undergo conformational changes to move specific molecules across the cell membrane in passive or active transport.

ATP-Powered Pumps

Transport proteins that utilize energy from ATP hydrolysis to transport molecules against their concentration gradient, such as the $Na^+/K^+$ ATPase.

Peripheral Membrane Proteins

Proteins loosely bound to the membrane surface via weak interactions, characterized by easy extraction and reversible surface associations.

Glycoproteins

Membrane carbohydrates covalently bonded to proteins, serving as signaling receptors, mediators of cell-cell interactions, and structural components.

Proteoglycans

Heavily glycosylated glycoproteins with long chains of polysaccharides called glycosaminoglycans (GAGs) attached to a core protein.

Glycolipids

Carbohydrates covalently bonded to lipids that participate in cell recognition, signal transduction, and cell adhesion.

Exocytosis

The process where vesicles fuse with the plasma membrane, releasing secretory proteins and positioning membrane carbohydrates on the extracellular face.