Membrane Slideshow 1 Flashcards
What is the cell membrane composed of
phospholipid bilayer
What diffuses through a cell membrane and what does not
lipid soluble molecules and gases, water cannot without help
what is the cell membrane impermeable to
organic anions
what does the permeability of the cell membrane depend on
molecular size, lipid solubility and charge
Along with water what else needs help of proteins to move across the membrane
polar molecules and ions
What is simple diffusion
small lipid soluble molecules and gases that pass either directly through bilayer or through pores
what is the movement of a substance in diffusion
it is down the gradient
what is the rate of diffusion proportional to
concentration gradient across the membrane
what is passive diffusion
no energy input required from ATP
what is faciilitated diffusion
process where molecules diffuse across membrane with help of carrier protein
what do carrier proteins aid with
movement of polar molecules (sugars and AA)
which direction is the movement of substance in F diffusion
down gradient
where does the energy come from to work F diffusion
concentration gradient of solute
what is active transport
moves selected molecules across membranes against [] gradient
how does the substance move in active transport
bind to protein carrier that changes conformation to move substance across membrane
