Flashcards in Membrane Structure And Function Deck (25):
Penetrate the hydrophobic core
What are the different effects of steroid cholesterol on membrane fluidity at different temperatures?
Warm temperature: cholesterol restrains movement of the phospholipids
Cool temperature: maintains fluidity by preventing tight packing
What are the six major functions of membrane proteins?
-Attachment to cytoskeleton and ECM
Bound to the surface of the membrane
Determines how your tissue works with you (such as blood type)
Fluid Mosaic model
States that a membrane is a fluid structure with a "mosaic" of various proteins embedded in it
What dissolves in the lipid bilayer and pass through membrane rapidly?
Hydrophobic (nonpolar) molecules, such CO2, and O2
Transport proteins (channel proteins)
Allow passage of hydrophilic substances across the membrane
Facilitate the passage of water
Tendency for molecules to spread out evenly into the available space
Diffusion of a substance across a biological membrane. No energy is expended by the cell to make this happen
Diffusion of water across a selectively permeable membrane
Which direction do substances diffuse?
Down their concentration gradient (from high to low concentration)
Solute concentration is the same as inside the cell; still movement but no net movement
Solute concentration (amount of non-water particles) is greater than that inside the cell; cell loses water and shrivels (plasmolyzed)
Solute concentration (amount of non-water particles) is less than that inside the cell; cell gains water (turgid; lysed (ruptured))
Control of salute concentration and water balance, is a necessary adaptation for life in such environments
(A paramecium pumps water out of the cell due to living in hypotonic solution)
Transport proteins speed the passive movement of molecules across the plasma membrane
(Aquaporins, ion channels)
Moves substance against their concentration. Requires energy, usually in the form of ATP.
Performed by specific proteins (or pumps) in the membranes
Large molecules, such as polysaccharides and proteins, cross the membrane in bulk via vesicles
The cell takes in macromolecules by forming vesicles from the plasma membrane
What are the three types of endocytosis?
Binding of ligands to receptors triggers vesicle formation
Any molecule that binds specifically to a receptor site of another molecule