Membrane-01 Flashcards
What is the cell membrane composed of?
a phospholipid bilayer.
What factors determine the permeability of the cell membrane? (3)
molecular size, lipid solubility, and charge.
What type of molecules are involved in simple diffusion, what direction do they move, what is not required?
the movement of small, lipid-soluble molecules and gases down their concentration gradient without ATP.
What type of molecules are transported in facilitated diffusion, what is used to help do this, which direction do the molecules move?
the movement of polar molecules across the membrane with the help of a carrier protein, down their concentration gradient.
which direction do molecules go in active transport, what is needed to do this?
process of moving molecules against their concentration gradient using energy from ATP.
What powers secondary active transport?
The kinetic energy from one substance moving down its gradient powers the transport of another substance up its gradient.
what do membrane channels form, and why do they form this, what properties are the basis for which molecules can pass through these membrane channels?
proteins that form pores through the membrane, allowing specific ions to diffuse through based on size and charge.
How do voltage-gated channels work?
open or close in response to changes in membrane potential.
What are endocytosis and exocytosis?
endocytosis is the inward pinching of the membrane to create a vesicle, while exocytosis is the fusion of vesicles with the membrane to release contents outside.
how many and which ions does the Na+/K+ pump into and out of the cell, what does it need to do this, what does it create as a result?
an enzyme that moves 3 Na+ ions out of the cell and 2 K+ ions into the cell using ATP, creating a concentration gradient.
What is the resting membrane potential (RMP) of a neuron and what is the main cause of this?
approximately -70 mV, primarily due to the diffusion of K+ ions out of the cell.
