Lab 2 Osmosis & Diffusion

Lipid bilayer (plasma membrane)

A protective barrier around the cell formed by a double layer of phospholipids with embedded proteins; selectively permeable.

Phospholipids

Major components of the plasma membrane that form the bilayer and contribute to its fluidity.

Membrane proteins

Proteins embedded in or associated with the lipid bilayer that aid in communication and transport.

Extracellular fluid

The fluid outside the cell that bathes the cell and surrounding environment.

Cytoplasm

The internal cell contents, excluding the nucleus, including cytosol and organelles.

Semipermeable membrane

A membrane that allows certain molecules to pass while blocking others.

Diffusion

Movement of solutes from an area of high concentration to an area of low concentration until equilibrium is reached.

Facilitated diffusion

Diffusion through membrane proteins (carriers or channels) that does not require energy.

Osmosis

Diffusion of water across a selectively permeable membrane; water moves toward higher solute concentration.

Osmotic gradient

Difference in solute concentration across a membrane that drives osmosis.

Active transport

Transport of substances against their concentration gradient that requires energy.

Primary active transport

Active transport that uses energy from ATP to move substances across the membrane.

Secondary active transport

Active transport powered by the energy stored in movement of another molecule down its gradient, not directly using ATP.

Vesicular transport

Bulk transport of substances via vesicles, including endocytosis, exocytosis, and transcytosis.

Endocytosis

Process by which the cell takes in material by engulfing it in a vesicle.

Exocytosis

Process by which vesicles fuse with the plasma membrane to release contents outside the cell.

Transcytosis

Vesicle-mediated transport of materials across the cell from one surface to the opposite surface.

Hypertonic

Solution with a higher solute concentration than inside the cell; water exits the cell, causing shrinkage.

Hypotonic

Solution with a lower solute concentration than inside the cell; water enters the cell, causing swelling.

Isotonic

Solution with equal solute concentration inside and outside the cell; no net water movement.

Carrier protein

Membrane protein that facilitates diffusion by binding and transporting specific solutes.

Channel protein

Membrane protein that forms a pore allowing specific ions or molecules to pass through."

Agar

Gel-forming substance from red algae used in microbiology and labs; consists of agarose and agaropectin.

Agarose

The main polysaccharide in agar that forms a gel matrix used in gel electrophoresis.

Gel electrophoresis

Technique that separates small molecules by size as they move through an agarose gel under an electric field.

Matrix (gel matrix)

The network formed by agarose in a gel that sieves molecules during electrophoresis.

Hemolysis

Rupture of red blood cells due to osmotic imbalance, often from exposure to hypotonic solutions.

Isotonic saline

A solution (0.9% NaCl) with a solute concentration similar to that of body fluids; used to prevent osmotic shifts.

Dehydration (cellular)

Loss of water from a cell, causing shrinkage and impaired function.