Membranes: The Interface Between Cells and Their Environment

These flashcards cover key concepts from the lecture on membrane structure and functions, fluidity, transport mechanisms, and cell communication.

What are the important functions of biological membranes?

Selective uptake and export of ions and molecules, cell compartmentalization, anchoring of the cytoskeleton, production of energy intermediates such as ATP, cell signaling, cell and nuclear division, adhesion of cells to each other and to the ECM.

What is the structure of biological membranes?

The framework of membranes is the phospholipid bilayer, composed of amphipathic phospholipids with hydrophobic regions facing inward and hydrophilic regions facing outward.

What model describes the structure of membranes?

The fluid-mosaic model describes membranes as a mosaic of lipid, protein, and carbohydrate molecules that allow for fluidity in movement.

What factors affect the fluidity of membranes?

Length of fatty acyl tails, presence of double bonds, and the presence of cholesterol.

What are the types of membrane transport?

Simple diffusion, facilitated diffusion, and active transport.

What is osmosis?

The diffusion of water to the side with less water concentration.

What happens to animal cells in a hypertonic solution?

Animal cells lose water and shrink, a phenomenon known as crenation.

What are the two classes of transport proteins?

Channels and transporters.

What is the difference between a uniporter, symporter, and antiporter?

A uniporter transports a single molecule or ion, a symporter transports two or more in the same direction, and an antiporter transports two or more in opposite directions.

What is exocytosis?

The process by which materials inside the cell are packaged into vesicles and excreted into the extracellular medium.

What is receptor-mediated endocytosis?

A type of endocytosis where the plasma membrane invaginates to form a vesicle that brings specific substances into the cell.

What are gap junctions and plasmodesmata?

Gap junctions are intercellular channels between animal cells for communication; plasmodesmata are similar structures connecting plant cells.

What types of cell junctions are present between cells?

Anchoring junctions and tight junctions.