Membrane Structure and Function

These flashcards cover the key concepts of membrane structure and function as outlined in the lecture notes.

What are the two types of transport across the cell membrane?

Passive transport and active transport.

What is passive transport?

The movement of small molecules across the cell membrane without the input of energy.

What is active transport?

The movement of molecules across a cell membrane requiring energy and transport proteins.

What are phospholipids?

The most abundant lipid in most membranes, forming a bilayer.

What does the fluid mosaic model describe?

The membrane as a mosaic of protein molecules bobbing in a fluid bilayer.

What happens to membrane proteins as temperatures cool?

Membranes switch from a fluid state to a solid state.

How does cholesterol affect membrane fluidity?

At warm temperatures, cholesterol restrains phospholipid movement; at cool temperatures, it maintains fluidity.

What are the two major types of membrane proteins?

Peripheral proteins and integral proteins.

What is the function of glycoproteins?

To serve as markers for cell identification.

What is the primary function of transport proteins?

To allow the passage of hydrophilic substances across the membrane.

What are aquaporins?

Channel proteins that facilitate the diffusion of water.

What is osmosis?

The diffusion of water across a selectively permeable membrane.

What is tonicity?

The ability of a surrounding solution to cause a cell to gain or lose water.

What occurs in a hypotonic solution?

A cell will gain water and possibly lyse.

What occurs in a hypertonic solution?

A cell will lose water, shrivel, and potentially die.

What is facilitated diffusion?

The passive movement of molecules across a membrane assisted by transport proteins.

What is the sodium-potassium pump?

An active transport system that moves sodium out and potassium into the cell.

What is the effect of the electrochemical gradient?

It drives the diffusion of ions across a membrane.

What is cotransport?

When active transport of a solute indirectly drives transport of other substances.

What happens during endocytosis?

The cell takes in macromolecules by forming vesicles from the plasma membrane.

What is receptor-mediated endocytosis?

A process where vesicle formation is triggered by the binding of ligands to receptors.