The boundary that separates the living cell from its surroundings
_________ ____________ is a characteristic of cell membranes that means what passes in and out is regulated. It allows some substances to cross the membrane more easily than others.
Having characteristics of being hydrophobic and hydrophilic, such as a phospholipid.
The basic structural component and most abundant lipid of cell membranes is ____________.
Fluid Mosaic Model
Describes a membrane as a fluid structure with a "mosaic" of various proteins embedded in it.
The diffusion of water across a selectively permeable membrane.
A passive process that involves the movement of substances or molecules from high solute concentration to low. It is also the tendency for molecules to spread out evenly into the available space.
Uses energy (usually in the form of ATP) to move solutes against their concentration gradients and to maintain concentration gradients that differ from their surroundings, i.e. sodium-potassium pump.
An ion transport protein that generates voltage across a membrane.
The cell takes in macromolecules by forming vesicles from the plasma membrane.
Also known as cellular eating. A cell engulfs a particle in a vacuole.
Also known as cellular drinking. Molecules dissolved in droplets are taken up when extracellular fluid is "gulped" into tiny vesicles.
Special receptor proteins catch molecules and bring them into the cell against a concentration gradient
Transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell
Occurs when active transport of a solute indirectly drives transport of other substances.
Proteins bounded to the surface of the membrane.
Proteins that penetrate the hydrophobic core.
Proteins that span the membrane.
What are the 6 major functions of membrane proteins?
Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton and extracellular matrix (ECM)
Hydrophobic (nonpolar) molecules
Can dissolve in the lipid bilayer and pass through the membrane rapidly, such as hydrocarbons.
Do not cross the membrane easily, such as ions and polar molecules.
Allow passage of hydrophilic substances across the membrane.
A type of transport protein that has a hydrophilic channel that certain molecules or ions can use as a tunnel.
Channel proteins that facilitate the passage of water.
A type of transport protein that binds to molecules and changes shape to shuttle them across the membrane.
The diffusion of a substance across a membrane with no energy investment.
The region along which the density of a chemical substance increases or decreases.
The ability of a surrounding solution to cause a cell to gain or lose water.
Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane.
Solute concentration is greater than that inside the cell; cell loses water.
Solute concentration is less than that inside the cell; cell gains water.
The control of solute concentrations and water balance that is a necessary adaptation for life in such environments.
A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now turgid (firm).
If a plant cell and its surroundings are isotonic, there is no net movement of water into the cell; the cell becomes flaccid (limp).
A process in which plant cells lose water in a hypertonic environment, making the membrane pull away from the cell wall and causing the plant to wilt.
Transport proteins speed the passive movement of molecules across the plasma membrane. I describe the passive assistance of a transport protein to move substances from high solute concentration to low. I require no energy expenditure, instead using transport proteins to pass through membranes. What am I?
Channel proteins that facilitate the diffusion of ions.
A type of ion channel that opens or closes in response to a stimulus.
Two combined forces that drive the diffusion of ions across a membrane: A chemical force (the ion's concentration gradient) and an electrical force (the effect of the membrane potential on the ion's movement).
The major electrogenic pump of animal cells
The main electrogenic pump of plants, fungi, and bacteria
What is the purpose of electrogenic pumps?
To help store energy that can be used for cellular work
Occurs by exocytosis and endocytosis and requires energy
How do small molecules and water enter or leave the cell?
Through the lipid bilayer or via transport proteins
How do large molecules, such as polysaccharides and proteins, cross the membrane?
In bulk via vesicles
What are the 3 types of endocytosis?
Phagocytosis, pinocytosis, and receptor-mediated endocytosis
Mastering Biology CH.7 Membrane Structure and Function37 terms