Chapter 8 - Biological Membranes Flashcards
What types of things cannot pass through the plasma membrane of the cell?
fat-soluble compounds cross easily, while larger and water-soluble compounds must seek alternative entry routes
Flippases
enzymes that assist in transition or “flip” between layers
Chylomicrons
transport essential fatty acids in the diet as triacylglycerols from the intestine
What are the four classes of sphingolipids?
ceramides, sphingomyelins, cerebrosides, and gangliosides
What are the good functions of cholesterol?
Regulates membrane fluidity and is necessary in the synthesis of all steroids
Tight Junctions
prevent solutes from leaking into space between cells via a paracellular route
Desmosomes
bind adjacent cells by anchoring to their cytoskeletons; primarily found at the interface between two layers of epithelial tissue
Hemidesmosomes
similar function, but their main function is to attach epithelial cells to underlying structures (like basement membrane)
What does a negative ΔG mean?
spontaneous process that does not require energy, (passive transport)
What does a positive ΔG mean?
nonspontaneous process and requires energy, (active transport)
What is a colligative property?
a physical property of solutions that is dependent on the concentration of dissolved particles, but not on the chemical identity of those dissolved particles
What is facilitated diffusion?
simple diffusion for molecules that are impermeable to the membrane (large, polar, or charged)
What is the resting potential for most cells?
-40 and -80 mV, but can raise as high as +35 mV
Outer Mitochondrial Membrane
highly permeable due to many large pores that allow passage of ions and small proteins
Inner Mitochondrial Membrane
restricted permeability, has cristae (numerous foldings) for integral proteins
