Membranes: Their Structure, Function, and Chemistry

Flashcards covering the key concepts and details about membrane structure, function, and chemistry.

What are the primary roles of membranes in cells?

Membranes define boundaries of a cell and its internal compartments, and they play multiple roles in cellular function.

Why are membranes considered effective permeability barriers?

Membranes have a hydrophobic interior that prevents the free passage of polar and hydrophilic substances.

What do membrane proteins regulate?

Membrane proteins regulate the transport of solutes across the membrane.

What is signal transduction in relation to membrane proteins?

Signal transduction is how signals are transmitted from the outer surface of a cell to its interior.

What are adhesive junctions and tight junctions?

Adhesive junctions hold cells together, while tight junctions block the passage of fluids between cells.

What is the fluid mosaic model?

The fluid mosaic model describes the membrane as a fluid lipid bilayer with a mosaic of proteins embedded or attached.

What types of lipids are found in membranes?

The main classes of membrane lipids are phospholipids, glycolipids, and sterols.

What role do sterols like cholesterol play in membranes?

Cholesterol stabilizes membrane fluidity and decreases permeability to ions and small polar molecules.

How do fatty acids affect membrane fluidity?

Long-chain and saturated fatty acids raise the transition temperature (Tm), while short-chain and unsaturated fatty acids lower it.

What is the significance of lipid rafts?

Lipid rafts are localized regions of membrane lipids involved in cell signaling, changing composition as lipids and proteins move.

What are the three categories of membrane proteins?

The three categories of membrane proteins are integral, peripheral, and lipid-anchored proteins.