BIOL 1107K - Cell Membrane and Transport

Vocabulary flashcards covering cellular membrane structure, passive and active transport mechanisms, osmosis, tonicity, and cell membrane components based on BIOL 1107K lecture notes.

Diffusion

The random motion of particles moving from an area of high concentration to an area of low concentration.

Simple Diffusion

The unassisted movement of a solute from high concentration to low concentration (towards equilibrium) requiring no energy, occurring across membranes only for small, nonpolar molecules.

Facilitated Diffusion

The movement of molecules down the concentration gradient (high to low) through a membrane protein, requiring no energy but requiring a protein to allow large or polar molecules across the phospholipid bilayer.

Ion Channels

Membrane channel proteins with high selectivity that allow passage of one type of ion and can open or close to control ion movement across the cell membrane.

Carrier Proteins

Membrane proteins that change conformation to transport a substance, such as glucose, across the cell membrane.

Aquaporins

A type of channel protein that allows water to pass in or out of the cell to facilitate osmosis.

Osmosis

The passive, energy-free movement of water across a selectively permeable membrane from low solute concentration to high solute concentration to equalize solute concentration across the membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water, depending on its concentration of solutes that cannot cross the cell membrane.

Isotonic Solution

A solution that has the same solute concentration inside and outside the cell, resulting in no net water movement and maintaining normal cell shape.

Hypertonic Solution

A solution with a higher solute concentration than the cell, causing water to move out of the cell and leading the cell to shrivel.

Hypotonic Solution

A solution with a lower solute concentration than the cell, causing water to move into the cell, which can cause cells to lyse.

Turgid

The firm state of plant cells in hypotonic conditions, where cell walls prevent cell lysis.

Plasmolyzed

The shrunken state of plant cells in hypertonic conditions, leading to wilting or cell death.

Sodium/Potassium Pump

An active transport mechanism that uses one molecule of $\text{ATP}$ to move three $\text{Na}^+$ ions out of the cell and two $\text{K}^+$ ions into the cell against their concentration gradient.

Exocytosis

An active, $\text{ATP}$-requiring process in which substances (such as newly made proteins or waste) are moved out of the cell in transport vesicles.

Endocytosis

An active, $\text{ATP}$-requiring process in which substances (such as nutrients or fluids) move into the cell through transport vesicles.

Doxorubicin

An FDA-approved nano drug used for treating ovarian cancer that uses liposomes (artificial phospholipid vesicles with a methoxypolyethylene glycol surface coating) encapsulating doxorubicin hydrochloride in an aqueous core.

Receptor-Mediated Endocytosis

A selective form of endocytosis demonstrated in immune cell recognition, such as HIV binding to a $\text{CD4}$ receptor and a $\text{CCR5}$ co-receptor on a host cell.

Fluid Mosaic Model

A model describing the cell membrane as fluid (components can migrate) and a mosaic (made up of phospholipids, cholesterol, and proteins).

Oligosaccharides

Branched glycoside-linked sugars composed of about $15$ monomers.

Glycoprotein

A membrane molecule formed when a membrane protein is covalently bonded to an oligosaccharide.

Glycolipid

A membrane molecule formed when an oligosaccharide is covalently bonded to a membrane lipid.

Extracellular Components

Non-cellular molecules secreted external to the plasma membrane that maintain connections between cells to help coordinate cellular activities.